Synthesis and structural characterisation of tris(diphenylthiophosphinoyl)methane and tris(diphenylthiophosphinoyl)methanide complexes of rhodium and iridium; X-ray structures of 2-C(P(S)Ph2)3-S,S>> and 2-C(P(S)Ph2)3-S,S>>

Article abstract of DOI:10.1016/0022-328X(91)83012-S

Reactions of 2, M = Rh or Ir, cod = cyclooctadiene, with CH3 give the complex cations, >⁺, which are isolated in high yield as BF4^- or ClO4^- salts.These are the first reported examples of CH3 complexes in which the methine proton is retained after coordination.The high acidity of this proton is demonstrated by easy deprotonation to corresponding > complexes.The 31P NMR spectrum of >BF4 remains a single line to -100 deg C whereas that of > is resolvedinto two resonances at -60 deg C, suggesting that the former complex is 5-coordinate with an η³ (S,S,S) ligand and the latter 4-coordinate, η² (S,S).The 4-coordinate structure is confirmed by X-ray diffraction studies of > and > which both show approximately square planar metal centers, η² ligands with the third sulfur non-coordinated ( dangling ), and trigonal planar geometry at the central carbon of the tris(phosphinesulfide) ligand. > and > crystallize in the Pbca space group (Z = 8) with respective unit cells: a = 20.427(4) Angstroem, b = 16.931(2) Angstroem, c = 23.138(3) Angstroem; and a = 22.140(6) Angstroem, b = 22.317(5) Angstroem, c = 14.792(3) Angstroem.Line shape analysis for a variable temperature 31P NMR study of > gives ΔG^deg++ 46 +/- 2 kJ mol^-1 for the dynamic exchange of coordinated and non-coordinated sulfur.