A series of hydridoplatinum(II) complexes stabilized with tribenzylphosphines: their preparation, and an empirical approach to the mutual influence of ligands

Abstract

The preparation, IR and NMR spectra of 123 platinum hydrides of the general formula, trans-PtHX(PBz 3) 2 or trans-PtHL(PBz 3) 2BPh 4 (X = a uninegative anionic ligand, L = a neutral donor molecule, Bz = benzyl), are described. Neutral platinum hydrides have been synthesized by the reduction of trans-PtCl 2-(PBz 3) 2 with NaBH 4, by the Michaelis—Arbuzov rearrangement, or by metathesis. Cationic hydridoplatinum(II) complexes are obtained from the reaction of trans-PtHX(PBz 3) 2 (X = Cl or NO 3) with a donor molecule (L) in the presence of NaBPh 4, or by coordinating a donor molecule through use of PtH(PBz 3) 2BPh 4 · 1 2 CH 2Cl 2. The observed trends in ν(PtH), τ(H), 1 J(PtH) and 1 J(PtP) in a series of the hydridobenzylphosphineplatinum(II) complexes are discussed in terms of “ trans- or cis-influences”, defined as the ability of a ligand to weaken the bond trans or cis to itself. The data support the view that a donor atom trans to the hydridic ligand is important in determining the strength of the PtH bond in this series. Some remarks on the distinctive characteristics of some complexes, e.g., dissociation of coordinated cycloalkanone from platinum(II) or stereochemical non-rigidity of the sym-dimethylurea ligand, are included. Tricyclohexylphosphine analogs also have been prepared for comparison.