A comparison of the rates of intramolecular hydrogen migration in the molecules [Mo(η-C7H8)2]n+ to give [Mo(η-C7H7)(η-C7H9)]n+, n= 0 or 1: crystal structures of [Mo(η-C7H8)2], [Mo(η-C7H7)(η-C7H9)], and [Mo(η-C7H8)2][BF4]

Abstract

Co-condensation of molybdenum atoms with cycloheptatriene gives [Mo(η-C₇H₈)₂](7), which rearranges thermally to [Mo(η-C₇H₇)(η-C₇H₉)], (8). Oxidation of (7) gives the cation [Mo(η-C₇H₈)₂]⁺, (9), which rearranges thermally to give [Mo(η-C₇H₇)(η-C₇H₉)]⁺, (10). The crystal structures of (7), (8) and (9) have been determined. The isomerizations of (7) to (8), and of (9) to (10) are clean, first-order, intramolecular processes, and, surprisingly, the rate of conversion of (9) to (10)(E_act. = 115 kJ mol^–1) is slower than for the conversion of (7) to (8)(E_act= 101 kJ mol^–1).