New platinum complexes with carbodiphosphorane as pincer ligand via ortho phenyl metallation

Abstract

The platinum complex [Pt(η 3-C 8H 11)(C 6H 4PPh 2CPPh 3)] ( 2) is a halve side o-phenyl insertion product resulting from the reaction of C(PPh 3) 2 and [I 2Pt(cod)] and is unstable in halogenated hydrocarbons. In a slow reaction 2 abstracts HCl from CH 2Cl 2, CHCl 3 or CDCl 3 (DCl) and converts the η 3-C 8H 11 ligand into cod which is replaced by Cl −. Simultaneously, a second insertion of the Pt atom into an o-phenyl CH bond occurs under movement of the o-phenyl proton to the ylidic carbon atom resulting in the C, C, C-pincer complex [ClPt{CH(PC 6H 4Ph 2) 2}] ( 3). Surprisingly, crystals of the unusual carbonyl complex [(CO)Pt{C(PC 6H 4Ph 2) 2}] ( 5) were obtained upon attempts to replace Cl − in 3 by PPh 3 in CHCl 3 solution. Instead, an intermediate was identified by 31P NMR spectroscopy in which the coordinated CH group is replaced by PPh 3; however, no crystals could be obtained. From the resulting oily material after some month crystals of 5 separated. We suggest, that hydrolysis of an intermediate CCl 2 ligand (from CHCl 3) to CO via a leaking stopcock has taken place. The compounds are characterized by X-ray analyses, 31P NMR, and IR spectroscopy.