The Cyclopentylpentaaquochromium(III) Ion: Synthesis, Characterization, and Kinetics of Acidolysis, Homolysis, and Electrophilic Cleavage Reactions

The complex [(H20)5Cr-c-C5H9]2+ is formed in the reaction of Cr2+ with H202 in aqueous solution saturated with cyclopentane. Reaction of Cr2+ with cyclopentyl radical, a step observed directly by pulse radiolysis (k = (8.0 - 1.0) X 107 M-1 s-1), yields (H20)5Cr-c-C5H92+, the radical being formed by abstraction from the hydrocarbon with HO·. The complex was isolated chromatographically and characterized by its absorption spectrum and the products of reactions (C5H9Br from. Br2, C5H9OH from homolysis in the presence of Fe3+ and Cu2+). It decomposes by parallel unimolecular pathways of acidolysis [formula-omitted] and homolysis [formula-omitted], although the latter is a reversible and thermodynamically unfavorable process, which occurs only in the presence of oxidizing agents. The complex also reacts in bimolecular displacement reactions (SE2 mechanism) with [formula-omitted], and [formula-omitted].