Preparation, infrared spectra, and structures of some [(π-dienyl) FeCo(CO)4(π-diene)] compounds

Abstract

The reactions of [(π-dienyl)FeCo(CO)₆](dienyl = C₅H₄, MeC₅H₄, and C₉H₇) with various dienes give [(π-dienyl)-FeCo(CO)₄(π-diene)] complexes (diene = norbornadiene, cyclohexa-1,3-diene, or 2,3-dimethylbuta-1,3-diene). In the solid state these appear to exist as either cis- or trans-carbonyl-bridged tautomers with structures similar to those of the related [{(π-dienyl)Fe(CO)₂}₂] and [{(π-diene)Co(CO)₂}₂] compounds. In solution, the two isomers are in equilibrium. Their relative abundance depends on the solvent, temperature, the (π-diene) ligands, and, to a lesser extent, the (π-dienyl) ligands.