Double dative bond between divalent carbon(0) and uranium


Dative bonds between p- and d-block atoms are common but species containing a double dative bond, which donate two-electron pairs to the same acceptor, are far less common. The synthesis of complexes between UCl4 and carbodiphosphoranes (CDP), which formally possess double dative bonds Cl4UCDP, is reported in this paper. Single-crystal X-ray diffraction shows that the uranium−carbon distances are in the range of bond lengths for uranium−carbon double bonds. A bonding analysis suggests that the molecules are uranium−carbone complexes featuring divalent carbon(0) ligands rather than uranium−carbene species. The complexes represent rare examples with a double dative bond in f-block chemistry. Our study not only introduces the concept of double dative bonds between carbones and f-block elements but also opens an avenue for the construction of other complexes with double dative bonds, thus providing new opportunities for the applications of f-block compounds.


Understanding the nature of chemical bonding is of great importance, especially for the bonding of carbon with other elements1,2,3,4. Usually, carbon uses all of its four valence electrons to form stable tetravalent carbon(IV) species. Since the first stable singlet carbene at room temperature was isolated by Bertrand and coworkers3, divalent carbon(II) chemistry, such as N-heterocyclic carbene (NHC)6,7,8,9 and cyclic (alkyl)(amino)carbenes10,11,12,13, has flourished. Carbenes, CR2, which contain one lone electron pair, can coordinate to numerous main group atoms and d-block or even f-block elements forming stable species via a single dative bond. If all four carbon valence electrons are retained as two-electron pairs, divalent carbon(0) compounds CL2 (“carbones”) are formed14,15,16,17,18,19,20,21,22,23,24,25. Thus, the fundamental difference between a carbene CR2 and a carbone CL2 is the number of electron lone-pairs that may serve as donors: carbenes are two-electron (single lone-pair) donors while carbones are four-electron (double lone-pair) donors. Although the first divalent carbon(0) species9, carbodiphosphorane (CDP), was reported already in 1961, the actual bonding situation was not fully understood until a theoretical study appeared in 2006 by Frenking and coworkers27,28,29. They showed that CDP can be considered as two phosphine ligands coordinated to a carbon atom in the excited 1D state with two lone electron pairs, which remain available for both σ- and π-donation simultaneously13. There are numerous complexes in which carbones bind to two acceptors31,32,33. In contrast, examples containing a double dative bond, which donates two lone electron pairs to the same acceptor are rare34,35,36,37. A comparative experimental work showed that carbenes and carbones exhibit distinctively different complexation behavior due to the varying number of lone-pair orbitals32. The chemistry of divalent carbon(0) has been focused mainly on main group compounds and transition metal element complexes. The bonding motif between divalent carbon(0) and f-block elements has received less attention. Since uranium plays fascinating roles in energy and catalysis research38,39,40,41,42,43, it is important to isolate species containing a new uranium−carbon bond, which could provide a deeper understanding of the nature of chemical bonding between main group elements and f-block metals.

In this paper, we report a set of complexes that possess a double dative bond between carbon and uranium. The complexes were obtained by the reaction of different CDPs with uranium tetrachloride (UCl4). Single-crystal X-ray diffraction reveals that the molecules possess rather short uranium−carbon bonds. Density functional theory (DFT) calculations confirm the double dative bond feature between carbon and uranium. The results of this study could be useful for the design of other compounds containing f-block atoms that exhibit double dative bonds between the metal and carbone ligands, and could provide new opportunities for the applications of f-block elements in catalysis or in the activation of small molecules.


Synthesis and characterization

We first designed and prepared a new tridentate CDP precursor, 1-(PF6)2, with two 2-(pyridyl)diphenylphosphine units (see Supplementary Methods). The corresponding CDP-UCl4 adduct (2) was readily synthesized by the deprotonation of compound 1-(PF6)2 with NaHMDS and subsequent reaction in situ of the resulting CDP with UCl4 (Fig. 1a). Complex 2 was isolated in 66% yield as yellow-green crystals after recrystallization at ‒35 °C overnight. The crystalline form of 2 shows low solubility in most organic solvents and easily decomposes to the free ligand. Consequently, the 31P nuclear magnetic resonance (NMR) spectrum shows two equivalent phosphine signals at ‒215.87 ppm for complex 2 along with the signal for 1 (Supplementary Fig. 1). The 1H NMR spectrum of complex 2 exhibits a broad range of peaks from +14.19 to −41.54 ppm (Supplementary Fig. 2).

Fig. 1

Synthesis of CDP-UCl4 adducts. Synthesis of double dative bond adducts 2 (a), 4 (b), and 6 (c) employ tridentate, bidentate, and monodentate CDP precursors 1-(PF6)2, 3-(Br)2, and 5-(Br)2, respectively. d Two major resonance structures of complex 2 with a double dative bond (2a) and with an electron-sharing U=C double bond (2b)

The solid-state structure of 2 was confirmed by an analysis of its X-ray diffraction pattern (Fig. 2a). The uranium atom adopts a twisted pentagonal bipyramidal geometry in which both pyridyl ligands are coordinated to the uranium center forming two five-membered rings. The average U−N and U−Cl bond lengths are 2.604(5) Å and 2.648(2) Å, respectively. The bond length of U1−C1 was found to be 2.471(7) Å, which is obviously shorter than the U−C bond distances found in the adducts of NHC with uranium (2.573 Å−2.788 Å) (based on a search of the Cambridge Structural Database, CSD version 5.39 (updates 2017)). This U−C bond length in complex 2 (2.471(7) Å) is in the range of U(IV)=C double bond distances (2.310 Å−2.578 Å) in complexes with bis(iminophosphorano)methandiide as ligands (based on a search of the Cambridge Structural Database, CSD version 5.39 (updates 2017)). An alternative description of 2 with a double bond between uranium and carbon is provided by the resonance structure 2b (Fig. 1d). This depicts a carbon(IV) atom with an electron-sharing U=C double bond in which uranium has a formal charge of −2. Analysis of the bonding suggests that 2a is the dominant resonance form contributing to the bonding situation.

Fig. 2

Molecular structures of CDP-UCl4 adducts 2, 4, and 6. ac Solid-state structures of 2 (a), 4 (b), and 6 (c) by X-ray crystallography with 50% probability ellipsoids. Solvent molecules are omitted for clarity. Selected experimental [calculated] bond distances (Å) and angles (deg) for 2: U1–C1 2.471(7) [2.425], U1–N1 2.625(5) [2.612], U1–N2 2.582(6) [2.577], U1–Cl1 2.649(2) [2.612], U1–Cl2 2.645(2) [2.577], U1–Cl3 2.644(2) [2.663], U1–Cl4 2.655(2) [2.651], C1–P1 1.701(7) [1.680], C1–P2 1.690(6) [1.684], P1-C1-P2 121.3(4) [123.0]. For 4: U1–C1 2.461(5) [2.461], U1–N1 2.537(4) [2.530], U1–Cl1 2.598(2) [2.617], U1–Cl2 2.570(2) [2.615], U1–Cl3 2.592(2) [2.566], U1–Cl4 2.622(2) [2.570], C1–P1 1.711(5) [1.692], C1–P2 1.699(5) [1.711], P1-C1-P2 120.6(3) [117.7]. For 6: U1–C1 2.411(3) [2.436], U1–Cl1 2.550(1) [2.544], U1–Cl2 2.604(1) [2.554], U1–Cl3 2.594(1) [2.603], U1–Cl4 2.634(1) [2.609], C1–P1 1.705(3) [1.699], C1–P2 1.719(3) [1.710], P1-C1-P2 125.05(16) [121.9]. Uranium, yellow-green; phosphorus, violet red; nitrogen, blue; chlorine, green; carbon, gray

The short U−C bond in complex 2 prompted us to appraise uranium−carbon multiple bond chemistry44,45,46. The first uranium carbene was reported in 1981, and was stabilized by a phosphorus substituent29. Subsequently, various species containing a uranium carbon double bond with one or two phosphorus substituents on the carbene carbon were reported48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63. Interestingly, most of the reported uranium carbenes utilize tridentate chelating methanediide ligands47–64]. Indeed, some of the uranium carbene species in the literature might be considered to contain non-negligible carbone character in their bonding49,56,54. In addition, species containing a U−C double bond, triple bond, or even quadruple bond were identified by matrix infrared spectroscopy and/or relativistic density functional calculations64,65,66,67,68,69. Very recently, a diuranium carbide cluster (U=C=U) was also stabilized inside a C80 fullerene cage50.

In order to investigate the effect of CDP ligands on the bonding between divalent carbon(0) and uranium, analogous bidentate and monodentate CDP precursors 3-(Br)2 and 5-(Br)2 were synthesized. As shown in Fig. 1b, c, treatment of UCl4 with the CDP ligands, generated by the in situ deprotonation of 3-(Br)2 and 5-(Br)2 with NaHMDS in THF, resulted in the formation of CDP-UCl4 adducts 4 and 6 in 52% and 59% crystalline yields, respectively, after recrystallization at −35 °C. Both crystals of complexes 4 and 6 totally decomposed after re-dissolved in common solvents. Fortunately, the 31P NMR spectrum of complex 4 was recorded from the in situ reaction solutions. The signals of two nonequivalent phosphorus centers in this species were observed at ‒125.51 and ‒155.13 ppm (Supplementary Fig. 3). Complex 6 represents an unusual non-chelated species with a double dative bond between carbon and an f-block element compared with reported work47,48,67, but its stability is significantly lower than that of chelating complexes 2 and 4.

The crystal structure of complex 4 (Fig. 2b) reveals a U1−C1 bond distance of 2.461(5) Å, which compares well with that found in complex 2. The bond distances of U1−N1 (2.537(4) Å) and average U−Cl (2.595(2) Å) in 4 were slightly shorter than those observed in complex 2. The pyridyl unit coordinates with uranium center to form a five-membered ring, generating a distorted octahedral configuration. An X-ray study of 6 showed the uranium to have a distorted octahedral structure, concerning a weak interaction between the uranium center and a phenyl carbon atom, with a U1−C1 bond length of 2.411(3) Å (Fig. 2c). The bond lengths of U1−C1 in all these complexes are obviously shorter than the U−C distances (2.573 Å−2.788 Å) typically observed in NHC-uranium adducts. These data suggest that the bond between the divalent carbon(0) of CDP and the uranium is a multiple bond.

The recording of reliable absorption spectra of these complexes is prevented by their poor stability in solution. Fourier-transform infrared (FT-IR) spectra demonstrated bands at 690 cm−1 for 2, 687 cm−1 for 4, and 686 cm−1 for 6, respectively. These data match excellently with those computed for U–C stretching (674 cm−1 for 2, 673 cm−1 for 4, and 671 cm−1 for 6, Supplementary Table 3), suggesting the intrinsic double dative bond between uranium center and carbone carbon atom. Furthermore, variable-temperature magnetic measurements were used to characterize these species in the solid state. The magnetic moment of 2 at 300 K is approximately 3.81 μB, which is slightly higher than the expected value (3.58 μB) for the 3H4 ground state of f2 uranium(IV). Upon cooling, the magnetic moments decrease smoothly to 0.37 μB at 1.8 K and tending to zero (Fig. 3 and Supplementary Figs. 4-6). The magnetic moments and trends of 4 and 6 are similar to those of 2, which are consistent with uranium(IV) centers in those species. The uranium(IV) centers in these complexes were further confirmed by the field-dependent magnetization data collected at 1.8 K (Supplementary Figs. 79).

Fig. 3

Magnetic characterization data. Variable-temperature SQUID magnetization data of complex 2 (black square), complex 4 (red circle), and complex 6 (blue triangle) at 0.1 T. Lines are a guide to the eye only

Theoretical studies

DFT calculations were performed to elucidate the bonding situation in 2, 4, and 6. The geometries of these species were optimized at the BP86-D3(BJ)/def2-TZVPP/Stuttgart RSC ECP level using scalar-relativistic effective core potentials for uranium (see Supplementary Methods). Calculations at various spin states suggest that 2, 4, and 6 have an electronic triplet ground state. Calculated structures at the electronic singlet and quintet state are much higher in energy (Supplementary Fig. 10). The calculated bond lengths and angles of the three complexes are in good agreement with the experimental data (Fig. 2). The differences between theory and experiment are within the range of solid-state effects and the accuracy of the methods.

We calculated the bond strength of the uranium−carbon bonds in 2, 4, and 6. The theoretically predicted bond dissociation energies (BDEs) suggest (reactions 1−3) that the introduction of pyridine substituents for phenyl enhances the bond strength, which can be explained with the contribution of the N → U dative bonds to the uranium-CDP bonds. The calculated BDE for 6 (De = 70.8 kcal mol−1) indicates that the unsupported UC double donor bond is rather strong. Hayton and coworkers44 previously reported that the upper limit for the U=C BDE value in the related system is 90 kcal mol−1, which is in good agreement with our results. Nonetheless, the values are significantly lower than the BDE value of Ta=C (i.e., 126 kcal mol−1) in Ta=CHR(CH2R)3 (R = SiMe3)52. This shows the difference in bond strength between bonds involving an actinide and a formal carbone and those with a transition metal and a formal alkylidene.

$${{\mathbf{2}}} \to {\mathrm{UCl}}_{\mathrm{4}}\left( {\,}^3{{\mathrm{A}}} \right){\mathrm{ + C}}\left( {{\mathrm{PPh}}_{\mathrm{2}}{\mathrm{Py}}} \right)_{\mathrm{2}}\,{{D}}_{{e}}{\mathrm{ = 91}}{\mathrm{.5}}\,{\mathrm{kcal}}\,{\mathrm{mol}}^{{\mathrm{ - 1}}},$$
$${{\mathbf{4}}} \to {\mathrm{UCl}}_{\mathrm{4}}\left( {\,}^3{{\mathrm{A}}} \right){\mathrm{ + C}}\left( {{\mathrm{PPh}}_{\mathrm{2}}{\mathrm{Py}}} \right)\left( {{\mathrm{PPh}}_{\mathrm{3}}} \right) {{D}}_{{e}}{\mathrm{ = 82}}{\mathrm{.8}}\,{\mathrm{kcal}}\,{\mathrm{mol}}^{{\mathrm{ - 1}}},$$
$${{\mathbf{6}}} \to {\mathrm{UCl}}_{\mathrm{4}}\left( {\,}^3{{\mathrm{A}}} \right){\mathrm{ + C}}\left( {{\mathrm{PPh}}_{\mathrm{3}}} \right)_{\mathrm{2}} \,{{D}}_{{e}}{\mathrm{ = 70}}{\mathrm{.8}}\,{\mathrm{kcal}}\,{\mathrm{mol}}^{{\mathrm{ - 1}}}.$$

The calculated spin densities in 2, 4, and 6 indicate that the unpaired electrons are localized mainly at the uranium atom (Supplementary Fig. 11). This agrees with the shape of the single occupied molecular orbitals (SOMO) and SOMO-1, which are also centered at uranium center (Supplementary Figs. 12-13). Figure 4 shows the highest occupied molecular orbital (HOMO) and HOMO-2 of complex 2, which may be identified with the π and σ dative bonds of Cl4CDP. The related MOs of 4 and 6 are very similar; they are shown in Supplementary Figs. 1213.

Fig. 4

Shape of the HOMO and the HOMO-2 of complex 2. The isosurface value is 0.03 e Å−3

More detailed information about the nature of the Cl4U−CDP interactions is available from energy decomposition analysis with natural orbitals for chemical valence (EDA-NOCV) calculations of 2, 4, and 6 using the fragments (3A) UCl4 and singlet CDP with their frozen geometries of the complexes as interacting species. Further details about the method are given in Supplementary Methods. Table 1 shows the numerical results.

Table 1 EDA-NOCV results by using the triplet (T) UCl4 and singlet (S) CDP fragments

The intrinsic interactions energies ΔEint exhibit the same trend for the uranium−carbon bond strengths as the BDEs (2 > 4 > 6). Inspection of the attractive terms indicates that the dispersion make a non-negligible contribution between 10 and 15% of the total attraction. Furthermore, the uranium−carbon bonds possess a more electrostatic than covalent character as revealed by the relative strength of ΔEelstat and ΔEorb. The most important information comes from the breakdown of the total orbital (covalent) interactions into pairwise orbital contributions ΔEorb(x). The strongest interactions ΔEorb(1) and ΔEorb(2) are due to the σ and π components of the double donation Cl4UCDP. The nature of the orbital interactions comes to the fore when inspecting the shapes of the associated deformation densities Δρ(1) and Δρ(2) in 6, which are shown in Fig. 5a. There is clearly a charge donation from the σ and π lone-pair electrons on carbon to the uranium atom. The next strongest interactions ΔEorb(3) and ΔEorb(4) come from the singly occupied orbitals, which involves some further donation from the CDP ligand to uranium. The remaining orbital terms are mainly due to polarization within the fragments.

Fig. 5

Plot of the deformation densities Δρ together with the associated interaction energies ΔEorb. Deformation densities Δρ1−4 of the pairwise orbital interactions in 6 (a) and 2 (b) between UCl4 and the CDP ligand. The energies are in kcal mol−1. The charge eigenvalues ν give an estimate of the relative size of the charge migration. The direction of the charge flow is red → blue

Figure 5b shows the deformation densities Δρ of the four strongest pairwise orbital interactions in complex 2. The stabilization energies ΔEorb(1) and ΔEorb(2) are again due to the σ and π components of the double donation Cl4UCDP. The shape of Δρ(3) and Δρ(4) suggest that ΔEorb(3) and ΔEorb(4) are associated with the additional N → U donation of the pyridine ligands, which have a similar strength as the Cl4U ← CDP σ donation. In summary, the EDA-NOCV calculations strongly suggest that the CDP units in 2, 4, and 6 serve as double donor ligands toward uranium. A previous study by Liddle and coworkers reported a gallium-uranium complex with a UGa σ and π bond53. They wrote that “π donation by carbene-type fragments may be more widespread than previously recognized”. Here we report an example where the ligand is a carbone CL2.

In order to identify the valence atomic orbitals of uranium, which serve as acceptor orbitals for the donor−acceptor interaction with the CDP ligands, we carried out natural bond orbital (NBO) calculations of 2, 4, and 6. Supplementary Fig. 14 shows the shape of two natural bond orbitals that can easily be identified with the σ and π bonds in Cl4UCDP. Both bonds are strongly polarized toward the carbon end, which agrees with the findings of Liddle and coworkers in the uranium complexes employing methanediide ligand54. Table 2 shows the numerical results of the NBO calculations. Inspection of the hybridization at uranium reveals that the σ and π acceptor orbitals are mainly composed of 5f and 6d atomic orbitals, with the former being the larger component. Specifically the U−C σ-bond and π-bonds in 2 are polarized with 83% and 91% at the carbon, respectively, which strongly supports the notation of carbon as double donor. The uranium part of the U−C σ-bond has 52% f and 39% d character. The NBO data for 4 and 6 are very similar to those of complex 2.

Table 2 Calculated NBO compositions of the U−C natural orbitals in the complexes 2, 4, and 6

The natural charges and bond orders are provided in Supplementary Table 4 where the charge distribution indicates that 0.64 (2), 0.52 (4) and 0.50 (6) e are transferred from CDP to UCl4 fragment. Therefore, the ligand behavior of CDP is significantly enhanced in the presence of the two pyridyl rings. The C1 center still carries a quite large negative charge (−1.39 to −1.43 e) and this might be due to the significant contribution from its dipolar resonance form and/or the electron density accumulation resulting from an electron transfer from PR3 to C1. In principle, both are responsible in varying degrees. The Nalewajski-Mrozek bond order (NMBO)74,75,76,77, which represents the combined covalent and ionic bond order, has been previously reported to be very well correlated with the U=C bond description. In our study, the NMBO of 2, 4, and 6 was computed as 1.30, 1.34, and 1.41, respectively, indicating the double bond character therein.

Finally, the results of quantum theory of atoms in molecules (QTAIM) analysis are provided in Table 3. Note that for covalent bonds, 2ρ(rc) is usually negative; however, this criterion often fails for the bonds involving heavier elements. This is because 2ρ(rc) derives from the three curvature values (λ1, λ2 and λ3) where first two terms are negative but λ3 is positive. For heavier elements, λ3 term often dominates over the other two terms making the overall 2ρ(rc) value positive. For these cases, the use of H(rc) is recommended which is usually negative for covalent bonds. In the present cases, although 2ρ(rc) is positive, the corresponding H(rc) values are negative for U−C1 and U−N bonds. Moreover, the H(rc) value in the former bond is considerably more negative than that in the latter one, indicating stronger covalent interaction in the former case. The weak interaction of the U−C2 (phenyl carbon) bond in 6 is reflected from the positive H(rc) value (Supplementary Fig. 15). We have also computed ellipticity of electron density (ε(rc)) at the BCP of U−C1 bond. In general, for a single bond (σ) and triple bond (σ+2π) which have cylindrical contours of ρ, the corresponding ε(rc) value is approximately zero, whereas for a double bond (σ+π), because of the asymmetric distribution of ρ in perpendicular to the bond path the ε(rc) value is greater than zero58. In the present complexes, the ε(rc) value turned out as 0.09 (2), 0.12 (4) and 0.11(6). Although these values reflect slight perturbation from an ideal single bond, they are significantly smaller than the other corresponding values reported for U=C bonds in chelated complexes which range from 0.22 to 0.5258. Therefore, the ellipticity data do not clearly corroborate with the outcome from the NBO and EDA-NOCV analyses. Perhaps, this might be due to the very polarized nature of the double dative bonds.

Table 3 QTAIM analysis of the complexes 2, 4, and 6


We have prepared a set of complexes formed between CDP ligands and UCl4, which contain double dative bonds between carbon and uranium. Single-crystal X-ray diffraction analysis revealed a short uranium−carbon bond in these species. Theoretical calculations suggest that the nature of the bond between the carbon of CDP and uranium is a double dative bond. Both of the σ and π dative bonds in Cl4UCDP are strongly polarized toward the carbon. Therefore, the concept of a double dative bond between carbon and f-block elements has been proposed. This finding shows that the carbones could serve as an effective ligand for the synthesis of f-block species with a double dative bond. These complexes reported herein further strengthen our understanding of the bonding between carbon and uranium, and thus the double dative bond might be a more general bonding motif in f-block chemistry. Our further studies will focus on the synthesis of other f-block species containing a double dative bond employ carbones as ligands, as well as investigations of their applications in small molecule activation.


General considerations

Experiments were performed under an N2 atmosphere using standard Schlenk-line and glove-box techniques. All solvents and reagents were dried and deoxygenated before use, using a solvent purification system. See the Supplementary Methods for detailed experimental procedures, crystallographic (Supplementary Tables 1-2), and computational analyses (Supplementary Dataset and Supplementary Tables 3-4).

Preparation of 2

NaHMDS (0.2 mL, 2 M in THF, 0.4 mmol) was added to an off-white suspension of ligand 1-(PF6)2 (166 mg, 0.2 mmol) in THF. The resultant yellowish brown solution was stirred at RT for 2 h. Subsequently, a pre-cooled THF solution of UCl4 (76 mg, 0.2 mmol) was added. A yellowish green precipitate formed immediately upon addition of UCl4. The suspension was stirred for another 1 h and then filtered through Celite and washed with THF (5 mL × 3). The residue was then dissolved in dichloromethane and the resultant yellowish green solution was concentrated to ca. 5 mL and cooled at –35 °C overnight to afford yellow-green crystals. Once obtained as crystalline material, 2 is insoluble in aromatic and aliphatic solvents, and consequently a satisfactory 13C NMR spectrum was not available. However, in dichloromethane-d2, complex 2 decomposes slowly, allowing for 1H and 31P NMR spectroscopic measurement. Crystalline yield: 122 mg, 66%. 1H-NMR (CD2Cl2, 298 K, 400 MHz): δ 14.19 (s), 9.71 (s), 8.79 (s), −7.35 (s), and −41.54 (s) ppm. 31P{1H}-NMR (CD2Cl2, 298 K, 162.0 MHz): −215.87 (s) ppm. Anal. Calcd. for C35H28Cl4N2P2U: C 45.77; H 3.07; N 3.05. Found: C 45.91; H 3.03; N 3.01. FTIR ν/cm−1 (Nujol): 1573 (w), 1438 (s), 1216 (w), 1106 (s), 989 (m), 918 (w), 787 (w), 770 (w), 743 (s), 690 (s), 561 (w), 530 (m), 495 (m).

Preparation of 4

A white suspension of 3-(Br)2 (141 mg, 0.2 mmol) in toluene (10 mL) was treated with 0.2 mL NaHMDS (2 M in THF, 0.4 mmol). The resultant yellow suspension was stirred at RT for 2 h and then filtered. The filtrate was concentrated to ca. 5 mL and a cold solution of UCl4 (76 mg, 0.2 mmol) in THF (5 mL) was added. The resultant mixture was stirred at RT for another 1 h before filtration, generating a yellowish green suspension. The residue was washed by toluene (5 mL × 3) and then dissolved in DCM. The green filtrate was concentrated and kept at −35 °C overnight to afford yellowish green micro crystalline product. The crystals were collected and washed with cold THF to afford complex 4 in 52% yield (95 mg). Once obtained as crystalline material from DCM, 4 is not soluble in aromatic and aliphatic solvents, and decomposes in polar solvents such as DCM. Alternatively, it was found that 4 could also crystalize from a mixture of deprotonated 3 and UCl4 in THF. Thus, the 31P NMR spectrum of 4 was attained by measuring the reaction mixture after 1 h in THF-d8. However, satisfactory 1H and 13C NMR spectra could not be obtained and a satisfactory electronic absorption spectrum is also not available for the same reason. 31P{1H}-NMR(THF-d8, 298 K, 162 MHz): δ –125.51 (d, J = 2 Hz), –155.13 ppm (d, J= 2.2 Hz). Anal. Calcd. for C36H29Cl4NP2U: C 47.13; H 3.19; N 1.53. Found: C 46.74; H 3.51; N 1.23. FTIR ν/cm−1 (Nujol): 1586 (w), 1439 (s), 1109 (m), 996 (w), 918 (s), 741 (s), 687 (m), 542 (w), 510 (w), 497 (w).

Preparation of 6

A white suspension of 5-(Br)2 (140 mg, 0.2 mmol) in toluene (10 mL) was treated with 0.2 mL NaHMDS (2 M in THF, 0.4 mmol). The resultant yellow suspension was stirred at RT for 2 h before filtration. The filtrate was concentrated to ca. 5 mL and a cold solution of UCl4 (76 mg, 0.2 mmol) in THF (5 mL) was added. The resultant mixture was stirred at RT for another 1 h, generating white precipitates. The solvent was removed in vacuo and the yellowish green residue was washed with toluene (5 mL × 3) and then dissolved in DCM and filtered. The green filtrate was concentrated and kept at −35 °C overnight to afford yellowish green microcrystals. Those crystals were collected and washed with cold THF to afford complex 6 in 59% yield (109 mg). Once obtained as crystalline material from DCM, 6 is not soluble in common organic solvent, and decomposes in THF and DCM. Attempts to characterize 6 from reaction mixtures in THF-d8 failed to obtain reliable information. Therefore, no spectral is available for complex 6. The reproducibility of the synthesis of complex 6 was assessed by solving and refining the data of single crystal collected from three independent syntheses. Those results were identical. Anal. Calcd. for C37H30Cl4P2U: C 48.49; H 3.30. Found: C 45.93; H 3.24. This complex consistently has low carbon content, possibly due to the high sensitivity. FTIR ν/cm−1 (Nujol): 1438 (s), 1109 (m), 996 (m), 918 (w), 797 (w), 736 (w), 686 (m), 559 (s), 542 (m), 499 (w).

Data availability

The X-ray crystallographic coordinates for structures reported in this study have been deposited at the Cambridge Crystallographic Data Centre (CCDC), under deposition numbers CCDC-1850097 (2), 1850102 (4), and 1850103 (6). These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via The data that support the findings of this study are available from the corresponding author upon reasonable request.


  1. 1.

    Frey, G. D., Lavallo, V., Donnadieu, B., Schoeller, W. W. & Bertrand, G. Facile splitting of hydrogen and ammonia by nucleophilic activation at a single carbon center. Science 316, 439–441 (2007).

    ADS  CAS  Article  Google Scholar 

  2. 2.

    Dyker, C. A. & Bertrand, G. Chemical bonding: Rethinking carbon. Nat. Chem. 1, 265–266 (2009).

    CAS  Article  Google Scholar 

  3. 3.

    Alcarazo, M., Lehman, C. W., Anoop, A., Thiel, W. & Fürstner, A. Coordination chemistry at carbon. Nat. Chem. 1, 295–301 (2009).

    CAS  Article  Google Scholar 

  4. 4.

    Frenking, G. Dative bonds in main-group compounds: a case for more arrows! Angew. Chem. Int. Ed. 53, 6040–6046 (2014).

    CAS  Article  Google Scholar 

  5. 5.

    Igau, A., Grützmacher, H., Baceiredo, A. & Bertrand, G. Analogous α,α’-bis-carbenoid triply bond species:  synthesis of a stable λ3-phosphinocarbene-λ5-phosphaacetylene. J. Am. Chem. Soc. 110, 6463–6466 (1988).

    CAS  Article  Google Scholar 

  6. 6.

    Arduengo, A. J., Harlow, R. L. & Kline, M. A stable crystalline carbene. J. Am. Chem. Soc. 113, 361–363 (1991).

    CAS  Article  Google Scholar 

  7. 7.

    Arduengo, A. J. Looking for stable carbenes: the difficulty in starting anew. Acc. Chem. Res. 32, 913–921 (1999).

    CAS  Article  Google Scholar 

  8. 8.

    Hopkinson, M. N., Richter, C., Schedler, M. & Glorius, F. An overview of N-heterocyclic carbenes. Nature 510, 485–496 (2014).

    ADS  CAS  Article  Google Scholar 

  9. 9.

    Peris, E. Smart N-heterocyclic carbene ligands in catalysis. Chem. Rev. 118, 9988–10031 (2017).

    Article  Google Scholar 

  10. 10.

    Lavallo, V., Canac, Y., Präsang, C., Donnadieu, B. & Bertrand, G. Stable cyclic (alkyl)(amino) carbenes as rigid or flexible, bulky, electron‐rich ligands for transition‐metal catalysts: a quaternary carbon atom makes the difference. Angew. Chem. Int. Ed. 44, 5705–5709 (2005).

    CAS  Article  Google Scholar 

  11. 11.

    Melaimi, M., Soleilhavoup, M. & Bertrand, G. Stable cyclic carbenes and related species beyond diaminocarbenes. Angew. Chem. Int. Ed. 49, 8810–8849 (2010).

    CAS  Article  Google Scholar 

  12. 12.

    Soleilhavoup, M. & Bertrand, G. Cyclic (alkyl)(amino)carbenes (CAACs): stable carbenes on the rise. Acc. Chem. Res. 48, 256–266 (2015).

    CAS  Article  Google Scholar 

  13. 13.

    Bertrand, G., Sioleilhavoup, M., Melaimi, M. & Jazzar, R. Cyclic (alkyl)(amino)carbenes (CAACs): recent developments. Angew. Chem. Int. Ed. 56, 10046–10068 (2017).

    Article  Google Scholar 

  14. 14.

    Tonner, R. & Frenking, G. C(NHC)2: Divalent carbon(0) compounds with N-heterocyclic carbene ligands—theoretical evidence for a class of molecules with promising chemical properties. Angew. Chem. Int. Ed. 46, 8695–8698 (2007).

    CAS  Article  Google Scholar 

  15. 15.

    Dyker, C. A., Lavallo, V., Donnadieu, B. & Bertrand, G. Synthesis of an extremely bent acyclic allene (a “carbodicarbene”): a strong donor ligand. Angew. Chem. Int. Ed. 47, 3206–3209 (2008).

    CAS  Article  Google Scholar 

  16. 16.

    Fürstner, A., Alcarazo, M., Goddard, R. & Lehmann, C. W. Coordination chemistry of ene-1,1-diamines and a prototype “carbodicarbene”. Angew. Chem. Int. Ed. 47, 3210–3214 (2008).

    Article  Google Scholar 

  17. 17.

    Kaufhold, O. & Hahn, F. E. Carbodicarbenes: divalent carbon(0) compounds. Angew. Chem. Int. Ed. 47, 4057–4061 (2008).

    CAS  Article  Google Scholar 

  18. 18.

    Lavallo, V., Dyker, C. A., Donnadieu, B. & Bertrand, G. Synthesis and ligand properties of stable five‐membered‐ring allenes containing only second‐row elements. Angew. Chem. Int. Ed. 47, 5411–5414 (2008).

    CAS  Article  Google Scholar 

  19. 19.

    Melaimi, M., Parameswaran, P., Donnadieu, B., Frenking, G. & Bertrand, G. Synthesis and ligand properties of a persistent, all‐carbon four‐membered‐ring allene. Angew. Chem. Int. Ed. 48, 4792–4795 (2009).

    CAS  Article  Google Scholar 

  20. 20.

    Fernández, I. et al. Exocyclic delocalization at the expense of aromaticity in 3,5-bis(π-donor) substituted pyrazolium ions and corresponding cyclic bent allenes. J. Am. Chem. Soc. 26, 7287–7291 (2009).

    Google Scholar 

  21. 21.

    Goldfogel, M. J., Roberts, C. C. & Meek, S. J. Intermolecular hydroamination of 1, 3-dienes catalyzed by bis(phosphine) carbodicarbene–rhodium complexes. J. Am. Chem. Soc. 136, 6227–6230 (2014).

    CAS  Article  Google Scholar 

  22. 22.

    Roberts, C. C., Matías, D. M., Goldfogel, M. J. & Meek, S. J. Lewis acid activation of carbodicarbene catalysts for Rh-catalyzed hydroarylation of dienes. J. Am. Chem. Soc. 137, 6488–6491 (2015).

    CAS  Article  Google Scholar 

  23. 23.

    Hsu, Y. C. et al. Synthesis and isolation of an acyclic tridentate bis(pyridine) carbodicarbene and studies on its structural implications and reactivities. Angew. Chem. Int. Ed. 54, 2420–2424 (2015).

    CAS  Article  Google Scholar 

  24. 24.

    Pranckevicius, C., Liu, L., Bertrand, G. & Stephan, D. W. Synthesis of a carbodicyclopropenylidene: a carbodicarbene based solely on carbon. Angew. Chem. Int. Ed. 55, 5536–5540 (2016).

    CAS  Article  Google Scholar 

  25. 25.

    Chen, W. C. et al. Carbodicarbenes: unexpected π-accepting ability during reactivity with small molecules. J. Am. Chem. Soc. 139, 12830–12836 (2017).

    CAS  Article  Google Scholar 

  26. 26.

    Ramirez, F., Desai, N. B., Hansen, B. & McKelvie, N. Hexaphenylcarbodiphosphorane, (C6H5)3PCP(C6H5)3. J. Am. Chem. Soc. 83, 3539–3540 (1961).

    CAS  Article  Google Scholar 

  27. 27.

    Tonner, R., Öxler, F., Neumüller, B., Petz, W. & Frenking, G. Carbodiphosphoranes: the chemistry of divalent carbon(0). Angew. Chem. Int. Ed. 45, 8038–8042 (2006).

    CAS  Article  Google Scholar 

  28. 28.

    Tonner, R. & Frenking, G. Divalent carbon(0)chemistry, part 1: parent compounds. Chem. Eur. J. 14, 3260–3272 (2008).

    CAS  Article  Google Scholar 

  29. 29.

    Tonner, R. & Frenking, G. Divalent carbon(0)chemistry, part 2: protonation and complexes with main group and transition metal Lewis acids. Chem. Eur. J. 14, 3273–3289 (2008).

    CAS  Article  Google Scholar 

  30. 30.

    Frenking, G. et al. New bonding modes of carbon and heavier group 14 atoms Si–Pb. Chem. Soc. Rev. 43, 5106–5139 (2014).

    CAS  Article  Google Scholar 

  31. 31.

    Alcarazo, M., Radkowski, K., Mehler, G., Goddard, R. & Fürstner, A. Chiral heterobimetallic complexes of carbodiphosphoranes and phosphinidene–carbene adducts. Chem. Commun. 49, 3140–3142 (2013).

    CAS  Article  Google Scholar 

  32. 32.

    Petz, W. Addition compounds between carbones, CL2, and main group Lewis acids: a new glance at old and new compounds. Coord. Chem. Rev. 291, 1–27 (2015).

    CAS  Article  Google Scholar 

  33. 33.

    Zhao, L., Hermann, M., Holzmann, N. & Frenking, G. Dative bonding in main group compounds. Coord. Chem. Rev. 344, 163–204 (2017).

    CAS  Article  Google Scholar 

  34. 34.

    Sundermeyer, J., Weber, K., Peters, K. & von Schnering, H. G. Modeling surface reactivity of metal oxides: synthesis and structure of an ionic organorhenyl perrhenate formed by ligand-induced dissociation of covalent Re2O7. Organometallics 13, 2560–2562 (1994).

    CAS  Article  Google Scholar 

  35. 35.

    Inés, B. et al. Synthesis, structure, and reactivity of a dihydrido borenium cation. Angew. Chem. Int. Ed. 50, 8400–8403 (2011).

    Article  Google Scholar 

  36. 36.

    Chi, C. et al. Preparation and characterization of uranium–iron triple‐bonded UFe(CO)3 and OUFe(CO)3 complexes. Angew. Chem. Int. Ed. 56, 6932–6936 (2017).

    CAS  Article  Google Scholar 

  37. 37.

    Lu, E., Wooles, A. J., Gregson, M., Cobb, P. J. & Liddle, S. T. A very short uranium(IV)-rhodium(I) bond with net double-dative bonding character. Angew. Chem. Int. Ed. 57, 6587–6591 (2018).

    CAS  Article  Google Scholar 

  38. 38.

    Fox, A. R., Bart, S. C., Meyer, K. & Cummins, C. C. Towards uranium catalysts. Nature 455, 341–349 (2008).

    ADS  CAS  Article  Google Scholar 

  39. 39.

    Arnold, P. L., Mansell, S. M., Maron, L. & McKay, D. Spontaneous reduction and C–H borylation of arenes mediated by uranium(III) disproportionation. Nat. Chem. 4, 668–674 (2012).

    CAS  Article  Google Scholar 

  40. 40.

    Halter, D. P., Heinemann, F. W., Bachmann, J. & Meyer, K. Uranium-mediated electrocatalytic dihydrogen production from water. Nature 530, 317–321 (2016).

    ADS  CAS  Article  Google Scholar 

  41. 41.

    Falcone, M., Chatelain, L., Scopelliti, R., Živković, I. & Mazzanti, M. Nitrogen reduction and functionalization by a multimetallic uranium nitride complex. Nature 547, 332–335 (2017).

    ADS  CAS  Article  Google Scholar 

  42. 42.

    Arnold, P. L. & Turner, Z. R. Carbon oxygenate transformations by actinide compounds and catalysts. Nat. Rev. Chem. 1, 0002 (2017).

    CAS  Article  Google Scholar 

  43. 43.

    Halter, D. P., Heinemann, F. W., Maron, L. & Meyer, K. The role of uranium–arene bonding in H2O reduction catalysis. Nat. Chem. 10, 259–267 (2018).

    CAS  Article  Google Scholar 

  44. 44.

    Hayton, T. W. Metal–ligand multiple bonding in uranium: structure and reactivity. Dalton Trans. 39, 1145–1158 (2010).

    CAS  Article  Google Scholar 

  45. 45.

    Hayton, T. W. Recent developments in actinide–ligand multiple bonding. Chem. Commun. 49, 2956–2973 (2013).

    CAS  Article  Google Scholar 

  46. 46.

    Gregson, M., Wooles, A. J., Cooper, O. J. & Liddle, S. T. Covalent uranium carbene chemistry. Comments on Inorganic Chemistry 35, 262–294 (2015).

    CAS  Article  Google Scholar 

  47. 47.

    Cramer, R. E., Maynard, R. B., Paw, J. C. & Gilje, J. W. A uranium-carbon multiple bond. Crystal and molecular structure of (ŋ 5-C5H5)3UCHP(CH3)2(C6H5). J. Am. Chem. Soc. 103, 3589–3590 (1981).

    CAS  Article  Google Scholar 

  48. 48.

    Fortier, S., Walensky, J. R., Wu, G. & Hayton, T. W. Synthesis of a phosphorano-stabilized U(IV)-carbene via one-electron oxidation of a U(III)-ylide adduct. J. Am. Chem. Soc. 133, 6894–6897 (2011).

    CAS  Article  Google Scholar 

  49. 49.

    Tourneux, J. C. et al. Uranium(IV) nucleophilic carbene complexes. Organometallics 30, 2957–2971 (2011).

    CAS  Article  Google Scholar 

  50. 50.

    Rungthanaphatsophon, P., Huang, P. & Walensky, J. R. Phosphorano-stabilized carbene complexes with short thorium(IV)− and uranium(IV)−carbon bonds. Organometallics 37, 1884–1891 (2018).

    CAS  Article  Google Scholar 

  51. 51.

    Cantat, T. et al. The U=C double bond: synthesis and study of uranium nucleophilic carbene complexes. J. Am. Chem. Soc. 131, 963–972 (2009).

    CAS  Article  Google Scholar 

  52. 52.

    Tourneux, J. C. et al. Easy access to uranium nucleophilic carbene complexes. Dalton Trans. 39, 2494–2496 (2010).

    CAS  Article  Google Scholar 

  53. 53.

    Mills, D. P. et al. A delocalized arene-bridged diuranium single-molecule magnet. Nat. Chem. 3, 454–460 (2011).

    CAS  Article  Google Scholar 

  54. 54.

    Cooper, O. J. et al. Uranium–carbon multiple bonding: facile access to the pentavalent uranium carbene [U{C(PPh2NSiMe3)2}(Cl)2(I)] and comparison of UV=C and UIV=C bonds. Angew. Chem. Int. Ed. 50, 2383–2386 (2011).

    CAS  Article  Google Scholar 

  55. 55.

    Tourneux, J. C. et al. Exploring the uranyl organometallic chemistry: from single to double uranium-carbon bonds. J. Am. Chem. Soc. 133, 6162–6165 (2011).

    CAS  Article  Google Scholar 

  56. 56.

    Ma, G., Ferguson, M. J., McDonald, R. & Cavell, R. G. Actinide metals with multiple bonds to carbon: synthesis, characterization, and reactivity of U(IV) and Th(IV) bis(iminophosphorano) methandiide pincer carbene complexes. Inorg. Chem. 50, 6500–6508 (2011).

    CAS  Article  Google Scholar 

  57. 57.

    Mills, D. P. et al. Synthesis of a uranium(VI)-carbene: reductive formation of uranyl(V)-methanides, oxidative preparation of a [R2C=U=O]2+ analogue of the [O=U=O]2+ uranyl ion (R = Ph2PNSiMe3), and comparison of the nature of UIV=C, UV=C, and UVI=C double bonds. J. Am. Chem. Soc. 134, 10047–10054 (2012).

    CAS  Article  Google Scholar 

  58. 58.

    Cooper, O. J. et al. The nature of the U=Cdouble bond: Pushing the stability of high-oxidation-state uranium carbenes to the limit. Chem. Eur. J. 19, 7071–7083 (2013).

    CAS  Article  Google Scholar 

  59. 59.

    Lu, E. et al. Synthesis, characterization, and reactivity of a uranium(VI) carbene imido oxo complex. Angew. Chem. Int. Ed. 53, 6696–6700 (2014).

    CAS  Article  Google Scholar 

  60. 60.

    Gregson, M. et al. Emergence of comparable covalency in isostructural cerium(IV)– and uranium(IV)–carbon multiple bonds. Chem. Sci. 7, 3286–3297 (2016).

    CAS  Article  Google Scholar 

  61. 61.

    Gregson, M. et al. The inverse-trans-influence in tetravalent lanthanide and actinide bis(carbene) complexes. Nat. Commun. 8, 14137 (2017).

    ADS  CAS  Article  Google Scholar 

  62. 62.

    Lu, E., Boronski, J. T., Gregson, M., Wooles, A. J. & Liddle, S. T. Silyl-phosphino-carbene complexes of uranium(IV). Angew. Chem. Int. Ed. 57, 5506–5511 (2018).

    CAS  Article  Google Scholar 

  63. 63.

    Wooles, A. J. et al. Uranium(III)-carbon multiple bonding supported by arene δ-bonding in mixed-valence hexauranium nanometre-scale rings. Nat. Commun. 9, 2097 (2018).

    ADS  Article  Google Scholar 

  64. 64.

    Lyon, J. T. & Andrews, L. Formation and characterization of the uranium methylidene complexes CH2=UHX (X=F, Cl, and Br). Inorg. Chem. 45, 1847–1852 (2006).

    CAS  Article  Google Scholar 

  65. 65.

    Lyon, J. T., Hu, H.-S., Andrews, L. & Li, J. Formation of unprecedented actinide carbon triple bonds in uranium methylidyne molecules. Proc. Natl Acad. Sci. USA 104, 18919–18924 (2007).

    ADS  CAS  Article  Google Scholar 

  66. 66.

    Li, J., Hu, H. S., Lyon, J. T. & Andrews, L. Chirality, agostic interactions, and pyramidality in actinide methylidene complexes. Angew. Chem. Int. Ed. 46, 9045–9049 (2007).

    CAS  Article  Google Scholar 

  67. 67.

    Lyon, J. T., Andrews, L., Hu, H. S. & Li, J. Infrared spectra and electronic structures of agostic uranium methylidene molecules. Inorg. Chem. 47, 1435–1442 (2008).

    CAS  Article  Google Scholar 

  68. 68.

    Hu, H. S., Qiu, Y. H., Xiong, X. G., Schwarz, W. E. & Li, J. On the maximum bond multiplicity of carbon: unusual CU quadruple bonding in molecular CUO. Chem. Sci. 3, 2786–2796 (2012).

    CAS  Article  Google Scholar 

  69. 69.

    Cho, H.-G. & Andrews, L. Matrix preparation and spectroscopic and theoretical investigation of small high oxidation-state complexes of groups 3-12, 14, lanthanide and actinide metal atoms: carbon-metal single, double and triple bonds. Coord. Chem. Rev. 335, 76–102 (2017).

    CAS  Article  Google Scholar 

  70. 70.

    Zhang, X. et al. A diuranium carbide cluster stabilized inside a C80 fullerene cage. Nat. Commun. 9, 2753 (2018).

    ADS  Article  Google Scholar 

  71. 71.

    Mao, W., Xiang, L., Maron, L., Leng, X. & Chen, Y. Nonchelated phosphoniomethylidene complexes of scandium and lutetium. J. Am. Chem. Soc. 139, 17759–17762 (2017).

    CAS  Article  Google Scholar 

  72. 72.

    Luo, L., Li, L. & Marks, T. J. Energetics of metal-ligand multiple bonds. Thermochemistry of tantalum(V) alkylidene formation. J. Am. Chem. Soc. 119, 8574–8575 (1997).

    CAS  Article  Google Scholar 

  73. 73.

    Liddle, S. T. et al. σ and π Donation in an unsupported uranium-gallium bond. Angew. Chem. Int. Ed. 48, 1077–1080 (2009).

    CAS  Article  Google Scholar 

  74. 74.

    Nalewajski, R. F. & Mrozek, J. Modified valence indices from the two-particle density matrix. Int. J. Quantum Chem. 51, 187–200 (1994).

    CAS  Article  Google Scholar 

  75. 75.

    Nalewajski, R. F., Mrozek, J., Formosinho, S. J. & Varandas, A. J. C. Quantum mechanical valence study of a bond-breaking-bond-forming process in triatomic systems. Int. J. Quantum Chem. 52, 1153–1176 (1994).

    CAS  Article  Google Scholar 

  76. 76.

    Nalewajski, R. F. & Mrozek, J. Hartree‐Fock difference approach to chemical valence: Three‐electron indices in UHF approximation. Int. J. Quantum Chem. 57, 377–389 (1996).

    CAS  Article  Google Scholar 

  77. 77.

    Michalak, A., DeKock, R. L. & Ziegler, T. Bond multiplicity in transition-metal complexes: Applications of two-electron valence indices. J. Phys. Chem. A 112, 7256–7263 (2008).

    CAS  Article  Google Scholar 

  78. 78.

    Bader, R. F. W., Slee, T. S., Cremer, D. & Kraka, E. Description of conjugation and hyperconjugation in terms of electron distributions. J. Am. Chem. Soc. 105, 5061–5068 (1983).

    CAS  Article  Google Scholar 

Download references


This research was supported by the National Natural Science Foundation of China (Grant Nos. 21772088 and 21703099), the Natural Science Foundation of Jiangsu Province (Grant Nos. BK20170635 and BK20170964), the Fundamental Research Funds for the Central Universities, the program of Jiangsu Specially-Appointed Professor, and the Young Elite Scientist Sponsorship Program of China Association of Science and Technology. S.P. thanks Nanjing Tech University for the postdoctoral fellowship and the High Performance Computing Center of Nanjing Tech University for supporting the computational resources. L.Z. and G.F. acknowledge financial support from Nanjing Tech University (Grant Nos. 39837123 and 39837132) and a SICAM Fellowship from Jiangsu National Synergetic Innovation Center for Advanced Materials.

Author information




C.Z., G.F. and L.Z. conceived this project. W.S. and X.S. performed the experiments and solved all the X-ray structures. C.Z. and W.S. analyzed the experimental data. S.P. conducted the theoretical calculations. L.Z. and G.F. analyzed the theoretical results. C.Z., L.Z. and G.F. drafted the paper with support from W.S. and S.W. All authors discussed the results and contributed to the preparation of the final manuscript.

Corresponding authors

Correspondence to Lili Zhao or Gernot Frenking or Congqing Zhu.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Electronic supplementary material

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Su, W., Pan, S., Sun, X. et al. Double dative bond between divalent carbon(0) and uranium. Nat Commun 9, 4997 (2018).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.