Cu(i) complex bearing a PNP-pincer-type phosphaalkene ligand with a bulky fused-ring Eind group: properties and applications to FLP-type bond activation and catalytic CO reduction.

Herein, we report the synthesis of [Cu(Eind2-BPEP)][PF6] (2) (Eind2-BPEP = 2,6-bis(2-Eind-2-phosphaethenyl)pyridine, Eind = 1,1,3,3,5,5,7,7-octaethyl-1,2,3,5,6,7-hexahydro-s-indacen-4-yl), a three-coordinated Cu(i) complex bearing a PNP-pincer-type phosphaalkene ligand with bulky fused-ring Eind groups. The Gutmann-Beckett test revealed that complex 2 is highly Lewis acidic and comparable in strength to B(C6F5)3, which is a relatively strong Lewis acid. In addition, 2 is more Lewis acidic than [Cu(Mes*2-BPEP)][PF6] (3), the analogous complex with less-bulky Mes* instead of Eind groups.

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.