Stable Two-Legged Parent Piano-Stool and Mixed Diborabenzene-E4 (E=P, As) Sandwich Complexes of Group 8.

Abstract

A cyclic alkyl(amino)carbene‐stabilized 1,4‐diborabenzene (DBB) ligand enables the isolation of 18‐electron two‐legged parent piano‐stool Fe0 and Ru0 complexes, [(η6‐DBB)M(CO)2], the ruthenium complex being the first of its kind to be structurally characterized. [(η6‐DBB)Fe(CO)2] reacts with E4 (E=P, As) to yield mixed DBB‐cyclo‐E4 sandwich complexes with planar E4 2− ligands. Computational analyses confirm the strong electron‐donating capacity of the DBB ligand and show that the E4 ligand is bound by four equivalent Fe−P σ bonds.