Synthesis, cyclic voltammetry and P-31 {H} NMR spectra of [M3E2L3](2+) clusters; M = Ni, Pd or Pt; E = S, Se or Te; L = bis(diphenylphosphino)methane, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, or 1,4-bis(diphenylphosphino)b

摘要

Clusters [M3E2(bis(diphenylphosphino)methane)(3)](2+) ([M3E2(dppm)(3)](2+); M=Pd or Pt, E=S; M=Pt, E=Se), [M3E2(1,3-bis(dipbenylphosphino)propane)(3)](2+) ([M3E2(dppp)(3)](2+); M=Ni, Pd or Pt, E=S or Se; M=Pd or Pt, E=Te) and [M3E2(1,4-bis(dipbenylphosphino)butane)(3)](2+) ([M3E2(dppb)(3)](2+); M=Pd, E=S; M=Ni, Pd or Pt, E=Se; M=Pd or Pt, E=Te) were prepared, and their cyclic voltammograms and P-31 {H} NMR spectra were measured. The cyclic voltammograms of the clusters depend on the chelate ring size and their chemical reversibility varies in the order dppe > dppp > dppb=dppm. Three [M3Te2(dppe)(3)](2+) (M=Ni, Pd or Pt) clusters synthesized previously give quasi-reversible cyclic voltammograms at 298 K and their standard heterogeneous charge-transfer rates, k(s), were estimated. The increase in the P-31 chemical shift for the ligands is in the order dppe > dppb > dppp > dppm, for clusters which have the same metal and chalcogenido ions; the order of the chemical shift for the metals follows the trend Ni > Pd > Pt, for clusters containing the same chalcogenido ion and the same phosphine. Computer simulation of the P-31 {H} NMR spectra for the [Pt3Se2L3](2+) (L=dppm, dppe, dppp or dppb) clusters was carried out to estimate the NMR parameters. The magnitude of (2)J(Pt-Pt) depends on the chelate ring size and follows the order dppm > dppe > dppp > dppb. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 17]