Coordination chemistry of 9-sila- and 9-germa-phenanthrenes-unique coordination modes in their metallene complexes

Ligand exchange reactions of 9-sila- and 9-germa-phenathrenes with chromium carbonyl complexes, [Cr(CH3CN)(3)(CO)(3)] and [Cr(eta(6)-benzene)(CO)(3)], were performed. Their reactions with [Cr(CH3CN)(3)(CO)(3)] afforded the corresponding eta(6)-complexes, in which Cr(CO)(3) moieties coordinated to the C-6-rings. However, those with [Cr(eta(6)-benzene)(CO)(3)] gave unique four-membered complexes bearing semibridging carbonyl ligands. All the structures of novel complexes were determined by NMR and X-ray crystallographic analysis.