Chelated eta(5)-cyclopentadienyl-eta-ethyl complexes of molybdenum and tungsten; molecular structure of W(eta(5)-C5H4CH2-eta-CH2)(CO)(3)

Molybdenum and tungsten complexes M(eta(5)-C5H4CH2-eta-CH2)(CO)(3) (M = Mo, W) containing the bidentate ethyl-functionalized cyclopentadienyl ligand C 5H4CH2CH2 have been synthesized by the reaction of spiro[2.4]hepta-4,6-dien e with M(CO)(3)L-3 (M = Mo: L-3 = 1,3,5-C6H3Me3: M = W; L = NCMe), Reaction of the more stable tungsten complex with C6H5ICl2 and HBF4 gave complexes of the type W(eta(5)-C5H4CH2CH2Cl)(CO)(3)Cl, W(eta(5)-C5H4CH2CH3)(CO)(3)Cl and W(eta(5)-C5H4CH2CH3(CO)(3)(FBF3), respectively. The crystal structure o f the tungsten tricarbonyl complex W(eta(5)-C5H4CH2-eta-CH2)(CO)(3) has bee n determined by X-ray crystal diffraction on a single crystal and shows a f our-legged piano stool structure. (C) 2000 Elsevier Science S.A. All rights reserved.