Coordination chemistry of [CH(PPh 2)(P(S)Ph 2) 2]: Pd, Pt, Rh, and Ir complexes, including the crystal and molecular structures of the ligand and a tripodal iridium complex, [Ir(cod){CH(PPh 2) (P(S)Ph 2) 2- P,S,S}]BF 4 · CH 2Cl 2

Abstract

The complex cations, [M(cod){CH(PPh 2)(P(S)Ph 2) 2- P,S,S}] +, M = Ir or Rh, and [MCl(PEt 3)(CH(PPh 2) (P(S)Ph 2) 2- P,S] +, M = Pt or Pd, are readily prepared as fluoroborate salts by reactions of the ligand, CH(PPh 2)(P(S)Ph 2) 2, with the chlorobridged complexes, [M 2Cl 2(cod) 2], M = Ir or Rh, cod = cycloocta-1,5-diene, and [M 2Cl 4(PEt 3) 2], M = Pt or Pd, under mild conditions in the presence of NaBF 4. Structures are assigned on the basis of 31P NMR spectra and, in the case of M = Ir, by X-ray diffraction. The iridium and rhodium complexes contain tripodal η 3- P,S,S coordinated ligands in contrast to the examples for palladium and platinum, where the ligands are bidentate η 2- P,S coordinated with the second PS group non-coordinated (“dangling”). In solution at 25°C, the palladium complex exhibits fluxional behaviour with rapid exchange between the coordinated and “dangling” PS groups. Both platinum and palladium complexes consist mainly of the isomers having the coordinated PS group trans to Cl,but small quantities of the other isomer are formed for both metals. The ligand 1, CH(PPh 2)(P(S)Ph 2) 2 crystallizes in the P2 1/ n (No. 14) space group ( Z = 4) with a = 19.867(9) Å, b = 18.889(7) Å, c = 8.828(4) Å, β = 100.47(5) ° and complex 3a, [Ir(cod)(CH(PPh 2)(P(S)Ph 2) 2- P,S,S]BF 4 CH 2Cl 2, in the P 1 (No. 2) space group ( Z = 2) with a = 10.899(6) Å, b = 21.653(9) Å, c = 11.124(5) Å, α = 85.14(4)°, β = 111.59(4)°, γ = 107.93(6)°. In 3a, iridium is five-coordinate with an η 3- P,S,S ligand and the two double bonds of the cod ligand in an irregular geometry. The structural parameters of the ligand, 1, are changed relatively little by coordination except for a narrowing of the PCP angles.