Syntheses of Photoactive Complexes. Electronic Spectra, Electrochemistry, and SCF-X alpha-DV Calculations for Bis(phosphine)palladium Oxalate and Dithiooxalate Complexes

摘要

Group 10 transition-metal bis(phosphine) oxalate compounds undergo photochemical conversion to the corresponding MI(2) species (L = PR3). This has been observed for M = Pt and Pd; however, we have found the analogous oxalate complexes of nickel difficult to prepare. Presumably the instability of bis-(phosphine)nickel oxalates reflects the inability of Ni(II) to support a cis square-planar geometry with sterically demanding phosphine ligands, and a weak-field oxalate ligand. To photochemically generate the NiL2 species we therefore prepared complexes containing the dithiooxalate-S,S' ligand for the entire series Nickel, Palladium, and Platinum. Photoreductive elimination of dithiooxalate could be a novel method for generating COS within the coordination sphere of a low-valent metal. Dithiooxalate complexes that are bound through sulfur usually contain a hard metal ion chelated to the oxygens or else bridge two metal centers.