1,1,1,3,3,3-Hexamethyltrisilanylene-bridged bis(cyclopentadienyl)tetracarbonyldiiron and its derivatives: Synthesis, properties and molecular structures

The title ring-bridged bis(cyclopentadienyl)diiron complexes [eta(5), eta(5)-C5H4,-Si(SiMe3)(2)-C5H4]Fe-2(CO)L( mu-CO)(2) [L = CO (1), P(OPh)(3) (2), P(OMe)(3) (3), PPh3 (4), PMe3 (5)] that contain exocyclic Si-Si bonds attached to the bridging silicon atom have been synthesized. The Si-Si bonds were found to be stable to the intramolecular iron centers under both thermal and photochemical conditions, in sharp contrast to the facile cleavage of the Si-Si bond in 1,1,2,2-tetramethyldisilanylene-bridged analogous complexes. The stability of the Si-Si bonds in the present cases may be attributed to the fact that these Si-Si bonds are spatially unapproachable by the intramolecular coordinatively unsaturated iron centers. Molecular structures of 1 and 2 have been determined by X-ray diffraction methods. An obvious conformational change due to substitution of CO for P(OPh)(3) was observed. (C) 2006 Elsevier Ltd. All rights reserved.