On the Geometrical Stability of Square-Planar Platinum(0) Complexes That Bear a PNP-Pincer-Type Phosphaalkene Ligand (Eind -BPEP).

The four-coordinate Pt complex [Pt(PPh )(Eind -BPEP)] (Eind=1,1,3,3,5,5,7,7-octaethyl-1,2,3,5,6,7-hexahydro-s-indacen-4-yl; BPEP=2,6-bis(1-phenyl-2-phosphaethenyl)pyridine), which bears a PNP-pincer-type phosphaalkene ligand (Eind -BPEP; PNP=N,N-bis(diphenylphosphine)-2,6-diaminopyridine), were found to adopt a square-planar configuration around the Pt center (τ =0.11). This coordination geometry is very uncommon for formal d complexes.

A Square-Planar Complex of Platinum(0).

The Pt complex [Pt(PPh )(Eind -BPEP)] with a pyridine-based PNP-pincer-type phosphaalkene ligand (Eind -BPEP) has a highly planar geometry around Pt with ∑(Pt)=358.6°. This coordination geometry is very uncommon for formal d complexes, and the Pd and Ni homologues with the same ligands adopt distorted tetrahedral geometries.