1H, 1H, 2H, 2H-Perfluoroalkyl-Functionalization of Ni(II), Pd(II) and Pt(II) Mono- and Diphosphine Complexes : minimizing the Electronic Consequences for the Metal Center

Abstract

A series of fluorous derivatives of group 10 complexes MCl2(dppe) and [M(dppe)2](BF4)2 (M = Ni, Pd or Pt; dppe = 1,2-bis(diphenylphosphino)ethane) and cis-PtCl2(PPh3)2 was synthesized. The influence of para-(1H,1H,2H,2H-perfluoroalkyl)dimethylsilyl-functionalization of the phosphine phenyl groups of these complexes, as studied by NMR spectroscopy, cyclovoltammetry (CV), XPS analyses, as well as DFT calculations, points to a weak steric and no significant inductive electronic effect. The steric effect is most pronounced for M = Ni and leads in the case of NiCl2(1c) (3c) and [Ni(1c)2](BF4)2 (7c) (1c = [CH2P{C6H4(SiMe2CH2CH2C6F13)-4}2]2) to a tetrahedral distortion from the expected square planar geometry. The solubility behavior of NiCl2[CH2P{C6H4(SiMe3-b(CH2CH2CxF2x+1)b)-4}2]2 (3: b = 1-3; x = 6, 8) in THF, toluene, and c-C6F11CF3 was found to follow the same trends as those observed for the free fluorous ligands 1. A similar correlation between the partition coefficient (P) of complexes 3 and free 1 was observed in fluorous biphasic solvent systems, with a maximum value obtained for 3f (b = 3, x = 6, P = 23 in favor of the fluorous phase).