Investigations into the Au^I and Pt^II Coordination Chemistry of Bidentate “cis‐Spanning” Ligands

Abstract

The novel bidentate PP and PN ligands o‐(Ph2P)−C6H4−C≡C−PPh2 (LPP) and o‐(Ph2P)−C6H4−4−(C5H9N−Me) (LPN), respectively, have been designed as long‐range “cis‐spanning“ ligands for the stabilization of heterodinuclear complexes containing two metal atoms in close proximity. The synthesis of heterodinuclear, formal AuIPtII complexes with the ligand LPP is straightforward. In the course of a one‐pot reaction, a surprisingly high selectivity for the coordination of AuCl and Pt(CNC) (CNC=2,6‐diphenylpyridine‐o,o’‐diate) to the phenyl‐bound and the alkyne‐bound PPh2 sites of LPP is observed, respectively. Chloride abstraction from the resulting heterodinuclear complex [(ClAu)(o‐Ph2P)−C6H4−C≡C−PPh2(Pt{CNC})] with Ag[SbF6] causes metal–metal bond formation and the generation of the cationic complex [LPPAuPt(CNC)][SbF6]. The high site selectivity for the coordination of the two metals to LPP was investigated by stoichiometric reactions of the ligand with one equivalent of the corresponding precursors. While analogous complexation experiments with LPN have not been successful, the synthesis of the heterodinuclear complex [(ClAu)(o‐Ph2P)−C6H4−4‐(C5H9N−Me)(PtCl2{dmso})] and of [LPN(AuCl)2] confirm the ability of LPN to serve as a ditopic ligand. In this context, it is noteworthy that [LPN(AuCl)2] constitutes the first amine–AuCl complex featuring a tertiary amine.