Syntheses involving co-ordinatively unsaturated cyclopentadienyl-molybdenum and -tungsten complexes. Molecular and crystal structure of [Mo·C(CF3):C(CF3)·C5H5(CF3C2CF3)(η5-C5H5)]

Abstract

The 16-electron chloro-complexes [MCl(CF₃C₂CF₃)₂(η⁵-C₅H₅)](M = MO or W) react with TISC₆F₅ to give compounds [M(SC₆F₅)(CF₃C₂CF₃]₂(η⁵-C₅H₅)]; the related species [M(SC₆F₅)(CO)(PhC₂Ph)(η⁵-C₅H₅)] were similarly obtained from [MCl(CO)(PhC₂Ph)(η⁵-C₅H₅)]. Cyclopentadienylthallium reacts with the compounds [MCl(CF₃C₂CF₃)₂(η₅-C₅H₅)] to afford insertion products [[graphic omitted]H₅(CF₃C₂CF₃)(η⁵-C₅H₅)], the molybdenum compound being characterised by a single-crystal X-ray diffraction study. It crystallises in the centrosymmetric monoclinic space-group P2₁/n. with lattice parameters a= 12.904(6). b= 9.641 (3). c= 15.302(6)Å, β= 103.34(4)°, The structure was elucidated via analysis of 2 148 independent diffracted data, and refined to R 0.39, R′ 0.044.

The molybdenum compound [MoCl(CF₃C₂CF₃)₂(η⁵-C₅H₅)] undergoes an unusual reaction with the tris-(pyrazolyl)borate anion to give a complex containing no boron but an η³-allyl group, linking two pyrazole ligands and formed by condensation of the two hexafluorobut-2-yne ligands originally co-ordinated to the metal. Buta-1,3- diene reacts with [MoCl(CF₃C₂CF₃)₂(η⁵-C₅H₅)] to give [MoCl₂(η⁴-C₄H₆(η⁵-C₅H₅)] and with [MoCl(CO)-(PhC₂Ph)(η⁵-C₅H₅)] to yield the same compound or [MoCl(CO)(η⁴-C₄H₆)(η⁵-C₅H₅], depending on the solvent. The tungsten compound [WCl(CO)(η⁴-C₄H₆)(η⁵-C₅H₅)] was also prepared. Reactions of bicyclo[2.2.1]-heptadiene with the compounds [MCl(CF₃C₂CF₃)₂(η⁵-C₅H₅)] were also studied.