Pentaphosphaferrocene-mediated synthesis of asymmetric organo-phosphines starting from white phosphorus

The synthesis of phosphines is based on white phosphorus, which is usually converted to PCl3, to be afterwards substituted step by step in a non-atomic efficient manner. Herein, we describe an alternative efficient transition metal-mediated process to form asymmetrically substituted phosphines directly from white phosphorus (P4). Thereby, P4 is converted to [Cp*Fe(η5-P5)] (1) (Cp* = η5-C5(CH3)5) in which one of the phosphorus atoms is selectively functionalized to the 1,1-diorgano-substituted complex [Cp*Fe(η4-P5R′R″)] (3). In a subsequent step, the phosphine PR′R″R‴ (R′ ≠ R″ ≠ R‴ = alky, aryl) (4) is released by reacting it with a nucleophile R‴M (M = alkali metal) as racemates. The starting material 1 can be regenerated with P4 and can be reused in multiple reaction cycles without isolation of the intermediates, and only the phosphine is distilled off.


Crystallographic details
SuiSupplementary Table ingle crystals were selected and measured on a Xcalibur  Gemini Ultra diffractometer equipped with an AtlasS2 CCD detector (2c, 2d, 3b), on a XtaLAB Synergy R DW system equipped with a HyPix-Arc 150 detector (2e, 3c, 3f, 4c), on a SuperNova diffractometer equipped with an Atlas CCD detector (3a), on a GV50 diffractometer equipped with a TitanS2 CCD detector (3d, 3e, 5), on a Xcalibur Gemini Ultra diffractometer equipped with a TitanS2 CCD detector (4a) or on a SuperNova Dualflex diffractometer equipped with a TitanS2 CCD detector (4b). The crystals were kept at T = 123(1) K or 203(2) K (2c) during data collection. Data collection and reduction were performed with CrysAlisPro. Using Olex2, the structures were solved with ShelXT and a least-square refinement on F 2 was carried out with ShelXL. All non-hydrogen atoms were refined anisotropically unless stated otherwise. Hydrogen atoms at the carbon atoms were located in idealized positions and refined isotropically according to the riding model. Figures were created with Olex2.

[Li(dme)3][Cp*Fe(η 4 -P5Me)] (2c):
The asymmetric unit contains one molecule of 2c. The P5 middle deck is disordered over two positions with a distribution of 95:5. To describe the disorder the SADI and SIMU restrains were applied. Further, is one of the DME molecules, which are coordinated to the lithium ion, disordered over two positions with an occupancy refined to 67:33. To describe this disorder the SIMU restrain was applied. The structure in solid state is given in Supplementary Figure 40 and S41. Crystallographic and refinement data are summarized in Supplementary Table 11. To describe these disorders the restraints SADI and SIMU were applied. The structure in solid state is given in Supplementary Figure 45 and S46. Crystallographic and refinement data are summarized in Supplementary Table 11.
[Cp*Fe(η 4 -P5Me2)] (3c): The asymmetric unit contains three molecules of 3c. One of them without any disorder, its structure in solid state is given in Supplementary Figure 47.
The other two show disorder: The P5 middle deck is disordered over two positions with a distribution of 83:17 / 91:9, respectively. To describe the disorder the SADI and SIMU restrains were applied. Crystallographic and refinement data are summarized in Supplementary Table 12.
[Cp*Fe(η 4 -P5 t BuMe)] (3e): The asymmetric unit contains half a molecule of 3d without any disorder. Compound 3d crystalizes in the acentric space group Im with a flack parameter of 0.000(3). The structure in solid state is given in Supplementary Figure 49. Crystallographic and refinement data are summarized in Supplementary Table 12.
[Cp*Fe(η 4 -P5PhMe)] (3f): The asymmetric unit contains two molecules of 3f without any disorder. The structure in solid state of one molecule is depicted in Supplementary  Figure 50. Crystallographic and refinement data are summarized in Supplementary Table  12.
SPMe i PrBnz (4a'): The asymmetric unit contains one molecule of 4a'. The P(S)Me i Pr unit is disordered over two positions with a distribution of 93:7. Due to the low occupancy of the second part, were only the sulphur and the phosphorus atoms anisotropically refined. The structure in solid state is given in Supplementary Figure 51 and S52. Crystallographic and refinement data are summarized in Supplementary Table 12. SP t BuMeBnz (4b'): The asymmetric unit contains one molecule of 4b' without any disorder. Since the measured crystal was twinned, a HKLF 5 refinement was applied (twin law: -0.5569 0.0005 0.4439 -0.0003 -1.0008 -0.0001 1.5524 -0.0002 0.5587; BASF 0.1610 (7) Supplementary Table 13.

[K(18c6)(thf)][Cp*Fe(η 4 -P4)] (5):
The asymmetric unit contains half a molecule of 5. The symmetry of the molecule is lower than the site symmetry (mirror plane), which causes the disorder of the Cp* ligand and one THF molecule over two positions. The complete structure in solid state is given in Supplementary Figure 55. Crystallographic and refinement data are summarized in Supplementary Table 13.   (2) 19.5371 (7) 18.5722 (2) 8.86570 (10)

Supplementary Figure 45.
Molecular structure of 3b with thermal ellipsoids at 50% probability level. The hydrogen atoms are omitted for clarity. The Cp* ligands are drawn in the wire frame model.

Supplementary Figure 46.
Side view of the molecular structure of 3b with thermal ellipsoids at 50 % probability level. The disorder is highlighted blue (Part 1) and green (Part 2). The hydrogen atoms are omitted for clarity.

Supplementary Table 22.
Selected bond length of 3b.

Supplementary Figure 50.
Molecular structure of 3f with thermal ellipsoids at 50% probability level. The hydrogen atoms are omitted for clarity. The Cp* ligand is drawn in the wire frame model.  Figure 51. Molecular structure of 4a' with thermal ellipsoids at 50% probability level. The hydrogen atoms are omitted for clarity.

Supplementary Figure 52.
Molecular structure of 4a' with thermal ellipsoids at 50 % probability level. The disorder is highlighted blue (Part 1) and green (Part 2) (grey = Part 0). The hydrogen atoms are omitted for clarity.

Supplementary Figure 55.
Molecular structure of 5 with thermal ellipsoids at 50% probability level. The hydrogen atoms are omitted for clarity. The Cp* ligand is drawn in the wire frame model.