449153-43-9Relevant academic research and scientific papers
Electrocatalytic reactions of a manganese-pyrylium complex
Shaw, Michael J.,Mertz, Jaime
, p. 3434 - 3442 (2002)
A salt of a metal-pyrylium σ-complex, pentacarbonyl-3-(2-methoxy-5,6-diphenylpyrylium)manganese(I) tetrafluoroborate (1BF4), has been prepared by the action of Mn(CO)5BF4 on methyl propiolate and diphenylacetylene. The pyrylium complex shows unusual resistance to electrophilic cleavage of the Mn - C bond by H+ and a low aptitude for migratory insertion reactions. The complex was studied by spectroscopic, voltammetric, and controlled potential electrolysis methods. 1BF4 displays two ligand-based one-electron reductions (E1° = -1.33 V, Epc,2 = -2.41 V vs Fc), the first of which is Nernstian. Its reactivity is enhanced by one-electron reduction, and it undergoes subsequent dimerization in THF (k273K = 285 M-1 s-1) and CH2Cl2 (k273K = 260 M-1 s-1) and a CO dissociation equilibrium (K ≈ 1.4 × 105, k = 0.7 s-1). In the presence of triphenylphosphine, a slow electrocatalytic CO-substitution reaction occurs for which a mechanism and rate constants have been determined by digital simulation. When 1BF4 is reduced in the presence of HSnPh3 and a proton donor, another electrocatalytic process results, presumably forming H2 at the electrode surface.
