Reaction of Bis(η-cyclopentadienyl)diiron tetracarbonyl with aryllithium reagents. A convenient synthesis of diiron carbonyl complexes with a bridging carbene ligand. crystal and molecular structures of [Fe2(η-C5H5)2(CO)2(μ-CO){μ-C (OC2H5)C6H5}] and [Fe2(η-(C5H5)2(CO)2(μ-CO){μ-C(OC2H5) C6H4CF3-P}]