η7-Cycloheptatrienylmolybdenum complexes. Part 1. Formation and oxidation of mixed-valence dimolybdenum complexes

Abstract

Tricarbonyl(η⁷-cycloheptatrienyl)molybdenum tetrafluoroborate reacts with halogenotrimethyl silanes to give initially the complexes [MoX(η⁷-C₇H₇)(CO)₂](X = Cl, Br, or I). These complexes undergo further reaction to yield the dimolybdenum species [Mo₂X₃(η⁷-C₇H₇)₂]. The tri-iodo-complex has also been obtained by treating [Mo(η⁶-C₆H₅Me)(η⁷-C₇H₇)][BF₄] with SiMe₃I. Electrochemical studies suggest the existence of cationic complexes [Mo₂X₃(η⁷-C₇H₇)₂]⁺, and this has been chemically accomplished with the mild oxidising agents p-NO₂C₆H₄N₂BF₄, PhN₂PF₆, and I₂. Moreover, [Mo(η⁷-C₇H₇)(CO)₃][BF₄] reacts with iodine to give [MO₂-(µ-I)₃(η⁷-C₇H₇)₂][I₃].