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Bond-strengthening π backdonation in a transition-metal π-diborene complex

Nature Chemistry volume 5, pages 115–121 (2013)Cite this article

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Abstract

Transition-metal catalysis is founded on the principle that electron donation from a metal to a ligand is accepted by an antibonding orbital of the ligand, thereby weakening one of the bonds in the ligand. Without this, the initial step of bond activation in many catalytic processes would simply not occur. This concept is enshrined in the well-accepted Dewar–Chatt–Duncanson model of transition-metal bonding. We present herein experimental and computational evidence for the first true violation of the Dewar–Chatt–Duncanson bonding model, found in a π-diborene complex in which an electron-rich group 10 metal donates electrons into an empty bonding π orbital on the ligand, and thereby strengthens the bond. The complex is also the first transition-metal complex to contain a bound diborene, a species not isolated before, either in its free form or bound to a metal.

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Figure 1: Valence-bond descriptions of π-alkyne and π-diborene complexes.
Figure 2: Computational results for complexes 1a and 1b.
Figure 3: Explanation of the orientations of π-alkyne and π-diborene ligands.
Figure 4: Synthetic results presented herein.
Figure 5: Molecular structure of 3 as derived from X-ray crystallography.

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References

  1. Cotton, F. A. & Wilkinson, G. Advanced Inorganic Chemistry (Wiley, 1988).

    Google Scholar 

  2. International Union of Pure and Applied Chemistry, Compendium of Chemical Terminology – the Gold Book (International Union of Pure and Applied Chemistry, 2011).

  3. Kubas, G. J. Metal dihydrogen and σ-Bond Complexes (Kluwer Academic/Plenum Publishers, 2001).

    Google Scholar 

  4. Kubas, G. J. Fundamentals of H2 binding and reactivity on transition metals underlying hydrogenase function and H2 production and storage. Chem. Rev. 107, 4152–4205 (2007).

    Article  CAS  PubMed  Google Scholar 

  5. Hall, C. & Perutz, R. N. Transition metal alkane complexes. Chem. Rev. 96, 3125–3146 (1996).

    Article  CAS  PubMed  Google Scholar 

  6. Bromberg, S. E. et al. The mechanism of a C–H bond activation reaction in room-temperature alkane solution. Science 278, 260–263 (1997).

    Article  CAS  Google Scholar 

  7. King, R. B. Nature of tris(alkyne)tungsten monocarbonyls and related complexes. Inorg. Chem. 7, 1044–1046 (1968).

    Article  CAS  Google Scholar 

  8. Otsuka, S. & Nakamura, A. Acetylene and allene complexes: their implication in homogeneous catalysis. Adv. Organomet. Chem. 14, 245–283 (1976).

    Article  CAS  Google Scholar 

  9. Templeton, J. L. 4-Electron alkyne ligands in molybdenum(II) and tungsten(II) complexes. Adv. Organomet. Chem. 29, 1–100 (1989).

    Article  CAS  Google Scholar 

  10. Dill, J. D., Schleyer, P. V. & Pople, J. A. Molecular-orbital theory of electronic-structure of organic compounds. 24. Geometries and energies of small boron-compounds comparisons with carbocations. J. Am. Chem. Soc. 97, 3402–3409 (1975).

    Article  CAS  Google Scholar 

  11. Knight, L. B., Kerr, K., Miller, P. K. & Arrington, C. A. ESR investigation of the HBBH(X(3).Sigma) radical in neon and argon matrices at 4K – comparison with ab-initio SCF and CI-calculations. J. Phys. Chem. 99, 16842–16848 (1995).

    Article  CAS  Google Scholar 

  12. Werner, H. Metal basicity as a synthetic tool in organometallic chemistry. Pure Appl. Chem. 54, 177–188 (1982).

    Article  CAS  Google Scholar 

  13. Braunschweig, H. & Dewhurst, R. D. Transition metals as Lewis bases: “Z-type” boron ligands and metal-to-boron dative bonding. Dalton Trans. 40, 549–558 (2011).

    Article  CAS  PubMed  Google Scholar 

  14. Bauer, J., Braunschweig, H. & Dewhurst, R. D. Metal-only Lewis pairs with transition metal Lewis bases. Chem. Rev. 112, 4329–4346.

  15. Frenking, G. & Frohlich, N. The nature of the bonding in transition-metal compounds. Chem. Rev. 100, 717–774 (2000).

    Article  CAS  PubMed  Google Scholar 

  16. Packett, D. L., Syed, A. & Trogler, W. C. Associative reactions of dihydridobis(trimethylphosphine)platinum(II) – molecular-structures of (diphenylacetylene)bis(trimethylphosphine)platinum and hydridotris(trimethylphosphine)platinum(II) tetraphenylborate. Organometallics 7, 159–166 (1988).

    Article  CAS  Google Scholar 

  17. Mitoraj, M. P., Michalak, A. & Ziegler, T. On the nature of the agostic bond between metal centers and beta-hydrogen atoms in alkyl complexes. An analysis based on the extended transition state method and the natural orbitals for chemical valence scheme (ETS-NOCV). Organometallics 28, 3727–3733 (2009).

    Article  CAS  Google Scholar 

  18. Mitoraj, M. P., Michalak, A. & Ziegler, T. A combined charge and energy decomposition scheme for bond analysis. J. Chem. Theor. Comp. 5, 962–975 (2009).

    Article  CAS  Google Scholar 

  19. Mavridis, A. & Moustakalimavridis, I. Reinvestigation of tolane. Acta Cryst. B 33, 3612–3615 (1977).

    Article  Google Scholar 

  20. Braunschweig, H., Dewhurst, R. D. & Schneider, A. Electron-precise coordination modes of boron-centered ligands. Chem. Rev. 110, 3924–3957 (2010).

    Article  CAS  PubMed  Google Scholar 

  21. Bertsch, S. et al. Towards homoleptic borylene complexes: incorporation of two borylene ligands into a mononuclear iridium species. Angew. Chem. Int. Ed. 49, 9517–9520 (2010).

    Article  CAS  Google Scholar 

  22. Pandey, K. K. Bis(borylene) complexes of cobalt, rhodium, and iridium [(η5-C5H5)M(BNX2)2] (X=Me, SiH3, SiMe3): a bonding analysis. Organometallics 30, 5851–5858 (2011).

    Article  CAS  Google Scholar 

  23. Wang, Y. et al. A stable neutral diborene containing a B=B double bond. J. Am. Chem. Soc. 129, 12412–12413 (2007).

    Article  CAS  PubMed  Google Scholar 

  24. Wang, Y. Z. & Robinson, G. H. Carbene stabilisation of highly reactive main-group molecules. Inorg. Chem. 50, 12326–12337 (2011).

    Article  CAS  PubMed  Google Scholar 

  25. Xu, L. C., Li, Q. S., King, R. B. & Schaefer, H. F. Coupling of fluoroborylene ligands to give a viable cyclopentadienyliron carbonyl complex of difluorodiborene (FB=BF). Organometallics 30, 5084–5087 (2011).

    Article  CAS  Google Scholar 

  26. Su, J. R., Li, X. W., Crittendon, R. C. & Robinson, G. H. How short is a Ga–Ga triple bond? Synthesis and molecular structure of Na2[Mes*2C6H3–GaGa–C6H3Mes*2] (Mes* = 2,4,6-i-Pr3C6H2): The first gallyne. J. Am. Chem. Soc. 119, 5471–5472 (1997).

    Article  CAS  Google Scholar 

  27. Hardman, N. J., Wright, R. L., Phillips, A. D. & Power, P. P. Synthesis and characterization of the neutral “digallene” Ar′GaGaAr′ and its reduction to Na2Ar′ GaGaAr′ (Ar′=2,6-Dipp2C6H3, Dipp 2,6-iPr2C6H3). Angew. Chem. Int. Ed. 41, 2842–2844 (2002).

    Article  CAS  Google Scholar 

  28. Hardman, N. J., Wright, R. J., Phillips, A. D. & Power, P. P. Structures, bonding, and reaction chemistry of the neutral organogallium(I) compounds (GaAr)n (n = 1 or 2) (Ar = terphenyl or related ligand): an experimental investigation of Ga–Ga multiple bonding. J. Am. Chem. Soc. 125, 2667–2679 (2003).

    Article  CAS  PubMed  Google Scholar 

  29. Wright, R. J., Brynda, M. & Power, P. P. Synthesis and structure of the “dialuminyne” Na2[Ar′AlAlAr′] and Na2[(Ar′′Al)3]: Al–Al bonding in Al2Na2 and Al3Na2 clusters. Angew. Chem. Int. Ed. 45, 5953–5956 (2006).

    Article  CAS  Google Scholar 

  30. Braunschweig, H. et al. Controlled homocatenation of boron on a transition metal. Nature Chem. 4, 563–567 (2012).

    Article  CAS  Google Scholar 

  31. Braunschweig, H., Radacki, K. & Uttinger, K. Synthesis and structure of a cationic platinum borylene complex. Angew. Chem. Int. Ed. 46, 3979–3982 (2007).

    Article  CAS  Google Scholar 

  32. Braunschweig, H., Damme, A. & Kupfer, T. Unexpected bonding mode of the diboran(4)yl ligand: combining the boryl motif with a dative Pt–B interaction. Angew. Chem. Int. Ed. 50, 7179–7182 (2011).

    Article  CAS  Google Scholar 

  33. Green, S. P., Jones, C. & Stasch, A. Stable magnesium(I) compounds with Mg–Mg bonds. Science 318, 1754–1757 (2007).

    Article  CAS  PubMed  Google Scholar 

  34. Bonyhady, S. J. et al. Beta-diketiminate-stabilized magnesium(I) dimers and magnesium(II) hydride complexes: synthesis, characterization, adduct formation, and reactivity studies. Chem. Eur. J. 16, 938–955 (2010).

    Article  CAS  PubMed  Google Scholar 

  35. Braunschweig, H., Ye, Q. & Radacki, K. High yield synthesis of a neutral and carbonyl-rich terminal arylborylene complex. Chem. Commun. 48, 2701–2703 (2012).

    Article  CAS  Google Scholar 

  36. Braunschweig, H. et al. Unsupported boron–carbon sigma-coordination to platinum as an isolable snapshot of sigma-bond activation. Nature Commun. 3, doi: 10.1038/ncomms1884 (2012).

  37. Braunschweig, H. et al. Ambient-temperature isolation of a compound with a boron–boron triple bond. Science 336, 1420–1422 (2012).

    Article  CAS  PubMed  Google Scholar 

  38. Amsterdam Density Functional (Theoretical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands, http://www.scm.com).

  39. Handy, N. C. & Cohen, A. J. Left–right correlation energy. Mol. Phys. 99, 403–412 (2001).

    Article  CAS  Google Scholar 

  40. Chong, D. P. Augmenting basis set for time-dependent density functional theory calculation of excitation energies: Slater-type orbitals for hydrogen to krypton. Mol. Phys. 103, 749–761 (2005).

    Article  CAS  Google Scholar 

  41. Chong, D. P., Van Lenthe, E., Van Gisbergen, S. & Baerends, E. J. Even-tempered Slater-type orbitals revisited: from hydrogen to krypton. J. Comput. Chem. 25, 1030–1036 (2004).

    Article  CAS  PubMed  Google Scholar 

  42. Van Lenthe, E. & Baerends, E. J. Optimized Slater-type basis sets for the elements 1–118. J. Comput. Chem. 24, 1142–1156 (2003).

    Article  CAS  PubMed  Google Scholar 

  43. Raffenetti, R. C. Even-tempered atomic orbitals 2. Atomic SCF wavefunctions in terms of even-tempered exponential bases. J. Chem. Phys. 59, 5936–5949 (1973).

    Article  CAS  Google Scholar 

  44. Bickelhaupt, F. M. & Baerends, E. J. in Reviews in Computational Chemistry Vol. 15 (eds K. B. Lipkowitz & D. B. Boyd) 1–86 (Wiley-VCH, 2000).

    Google Scholar 

  45. Morokuma, K. Why do molecules interact – origin of electron donor–acceptor complexes, hydrogen-bonding, and proton affinity. Acc. Chem. Res. 10, 294–300 (1977).

    Article  CAS  Google Scholar 

  46. Ziegler, T., Rauk, A. & Baerends, E. J. Calculation of multiplet energies by Hartree–Fock–Slater method. Theor. Chim. Acta 43, 261–271 (1977).

    Article  CAS  Google Scholar 

  47. Stephens, P. J., Devlin, F. J., Chabalowski, C. F. & Frisch, M. J. Ab-initio calculation of vibrational absorption and circular-dichroism spectra using density-functional force-fields. J. Phys. Chem. 98, 11623–11627 (1994).

    Article  CAS  Google Scholar 

  48. van Lenthe, E., Baerends, E. J. & Snijders, J. G. Relativistic regular 2-component Hamiltonians. J. Chem. Phys. 99, 4597–4610 (1993).

    Article  CAS  Google Scholar 

  49. van Lenthe, E., Ehlers, A. & Baerends, E. J. Geometry optimizations in the zero order regular approximation for relativistic effects. J. Chem. Phys. 110, 8943–8953 (1999).

    Article  CAS  Google Scholar 

  50. Bouten, R. et al. Relativistic effects for NMR shielding constants in transition metal oxides using the zeroth-order regular approximation. J. Phys. Chem. A 104, 5600–5611 (2000).

    Article  CAS  Google Scholar 

  51. Baerends, E. J., Ellis, D. E. & Ros, P. Self-consistent molecular Hartree–Fock–Slater calculations – I. The computational procedure. Chem. Phys. 2, 41–51 (1973).

    Article  CAS  Google Scholar 

  52. Mayer, I. Charge, bond order and valence in the ab initio SCF theory. Chem. Phys. Lett. 97, 270–274 (1983).

    Article  CAS  Google Scholar 

  53. Fowe, E. P., Therrien, B., Süss-Fink, G. & Daul, C. Electron-structure calculations and bond order analysis using density functional theory of cationic dinuclear arene ruthenium complexes. Inorg. Chem. 47, 42–48 (2008).

    Article  PubMed  CAS  Google Scholar 

  54. Hirshfeld, F. L. Bonded-atom fragments for describing molecular charge-densities. Theor Chim Acta 44, 129–138 (1977).

    Article  CAS  Google Scholar 

  55. Wiberg, K. B. & Rablen, P. R. Comparison of atomic charges derived via different procedures. J. Comput. Chem. 14, 1504–1518 (1993).

    Article  CAS  Google Scholar 

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Acknowledgements

Financial support by the Deutsche Forschungsgemeinschaft is gratefully acknowledged.

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Authors and Affiliations

  1. Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, Würzburg, 97074, Germany

    Holger Braunschweig, Alexander Damme, Rian D. Dewhurst & Alfredo Vargas

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  1. Holger Braunschweig
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  2. Alexander Damme
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  3. Rian D. Dewhurst
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  4. Alfredo Vargas
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Contributions

H.B. and R.D.D. conceived and supervised the study, A.V. performed the computational experiments and A.D. performed the syntheses and the X-ray crystallographic measurements. R.D.D. and A.V. co-wrote the paper.

Corresponding author

Correspondence to Holger Braunschweig.

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The authors declare no competing financial interests.

Supplementary information

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Supplementary information (PDF 1900 kb)

Supplementary information

Crystallographic data for compound Br2B2Dur2. (CIF 18 kb)

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Crystallographic data for compound 2. (CIF 28 kb)

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Crystallographic data for compound 3. (CIF 26 kb)

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Braunschweig, H., Damme, A., Dewhurst, R. et al. Bond-strengthening π backdonation in a transition-metal π-diborene complex. Nature Chem 5, 115–121 (2013). https://doi.org/10.1038/nchem.1520

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