Chelated η5-cyclopentadienyl-η-ethyl complexes of molybdenum and tungsten; molecular structure of W(η5-C5H4CH2-η-CH2)(CO)3

Molybdenum and tungsten complexes M(h 5 -C5H4CH2-h-CH2)(CO)3 (M Mo, W) containing the bidentate ethyl-functionalized cyclopentadienyl ligand C5H4CH2CH2 have been synthesized by the reaction of spiro[2.4]hepta-4,6-diene with M(CO)3L3 (M Mo; L31,3,5-C6H3Me3 ;M W; LNCMe). Reaction of the more stable tungsten complex with C6H5ICl2 and HBF4 gave complexes of the type W(h 5 -C5H4CH2CH2Cl)(CO)3Cl, W(h 5 -C5H4CH2CH3)(CO)3Cl and W(h 5 -C5H4CH2CH3)(CO)3(FBF3), respectively. The crystal structure of the tungsten tricarbonyl complex W(h 5 -C5H4CH2-h-CH2)(CO)3 has been determined by X-ray crystal diffraction on a single crystal and shows a four-legged piano stool structure. © 2000 Elsevier Science S.A. All rights reserved.