Synthesis, characterization, and chemistry of titanium(IV), titanium(III), zirconium(IV), and hafnium(IV) complexes of phosphine sulfides and selenides. The crystal and molecular structures of Cp2Ti(SPCy2)2, Cp2Ti(S2PCy2), and Cp2Ti(Se2PPh2)

Article abstract of DOI:10.1021/om00150a025

The complexes Cp₂M(SPR₂)₂ (M = Ti, R = Cy (1); M = Zr, R = Ph (2), R = Cy (3); M = Hf, R = Ph (4), R = Cy (5)) were prepared by reaction of LiSPR₂ with the appropriate metallocene dihalide. 1 crystallizes in the triclinic space group P1, with a = 7.999 (2) ?, b = 13.102 (5) ?, c = 16.626 (6) ?, α = 96.71 (3)°, β = 101.43 (3)°, γ = 91.14 (3)°, V = 1694 (1) ?³, and Z = 2. Species 2-5 could also be prepared from the reaction of Cp₂M(PR₂)₂ (M = Zr, Hf) with elemental sulfur. Reactions of Cp₂TiCl₂ with LiXPR₂ (X = S, R = Ph; X = Se, R = Ph, Cy) or solutions of 1 on standing yield Ti(III) species by reductive elimination of (XPR₂)₂. These Ti(III) complexes are formulated as Cp₂TiXPR₂ (X = S, R = Ph (6), Cy (7); X = Se, R = Ph (8), R = Cy (9)) on the basis of EPR data. These Ti(III) compounds are unstable and slowly convert by chalcogen atom abstraction to the complexes Cp₂TiX₂PR₂ (X = S, R = Ph (12), R = Cy (13); X = Se, R = Ph (14), R = Cy (15)). 13 crystallizes in the orthorhombic space group Pbna, with a = 9.075 (3) ?, b = 34.052 (5) ?, c = 14.318 (5) ?, V = 4424 (3) ?³, and Z = 8. 14 crystallizes in the monoclinic space group P2₁/c, with a = 8.471 (3) ?, b = 29.868 (9) ?, c = 8.336 (3) ?, β = 104.47 (3)°, V = 2030 (1) ?³, and Z = 4. 12-15 as well as the analogues (X = S, R = Me (10), R = Et (11)) can also be prepared by photolysis of Cp₂Ti(CO)₂ in the presence of (SPR₂)₂ or XPR₂H. Alternatively, 12-15 can be prepared by reaction of either LiXPR₂ or LiX₂PR₂ with [Cp₂TiCl]₂. Complexes 2-5 slowly convert to the complexes [Cp₂MX]₂ (M = Zr, X = S (16), X = Se (17); M = Hf, X = S (18), X = Se (19), respectively). The preparation of 16-19 can also be achieved by direct reaction of 2-5 with Cp₂M(PR₂)₂. The differences between the Ti chemistry and that of Zr and Hf are attributed to the ease of reduction of Ti(IV) to Ti(III).