Mononuclear half-sandwich rhodium complexes containing phenylchalcogenolato ligands: a multinuclear (H-1, C-13, P-31, Se-77, Rh-103,Te-125) magnetic resonance study

Diphenyl dichalcogenides react with CpRh(PMe3)(CO) (1) to give the cyclopen tadienyl complexes CpRh(PMe3)(EPh)(2) (E = S (2a), Se (2b) and Te (2c)) and carbon monoxide. The analogous pentamethylcyclopentadienyl complexes Cp*Rh (PMe3)(EPh)(2) (E = S (4a), Se (4b) and Te (4c)) were prepared from Cp*Rh(P Me3)Cl-2 (3) and the chalcogenolates, NaSPh or LiEPh (E = Se, Te). With 1,2 -benzenedithiol in the presence of triethylamine, CpRh(PMe3)(S2C6H4), (6a) and Cp*Rh(PMe3)(S2C6H4) (7a) could be obtained starting from either CpRh(PM e3)I-2 (5) or Cp*Rh(PMe3)Cl-2 (3), respectively. The molecular geometry of Cp*Rh(PMe3)(SePh)(2) (4b) was determined by a single crystal structure anal ysis which confirmed a distorted tetrahedral arrangement of the ligands. Al l compounds were characterised by H-1-, C-13-, P-31-, Rh-103- and, where po ssible, by Se-77- or Te-125-NMR spectroscopy. A negative sign of (1)J(Rh-10 3, C-13(Cp)) (reduced coupling constant K-1(Rh-103, C-13(Cp)) > 0) was dete rmined by selective C-13{H-1, P-31} triple resonance experiments for 2a and 4a-4c. (C) 1999 Elsevier Science S.A. All rights reserved.