Matrix photochemistry of ethyltrioxorhenium(VII), C2H5ReO3: Tautomerisation via β-hydrogen migration with the sequential formation of two different ethene derivatives

IR spectroscopic measurements have been used to chart the matrix photochemistry of ethyltrioxorhenium(VII). Broad-band UV–visible light (200 ≤ λ ≤ 800 nm) results in the migration of a β-hydrogen atom of the ethyl group with the sequential formation of two tautomers, the first a weakly OH-bound ethene complex, C2H4·HOReO2, and the second the η2-coordinated ethene derivative (η2-C2H4)Re(OH)O2. There is no evidence of the carbene derivative CH3CHRe(OH)O2 which might have been expected by analogy with the behaviour of methyltrioxorhenium, CH3ReO3, under similar circumstances. Assignments of the IR absorption bands are made and their carriers identified on the basis of experiments with C2D5ReO3 and CH3CD2ReO3 and by comparison with the vibrational properties either forecast by density functional theory (DFT) calculations or determined experimentally for related molecules.