Photochemistry of (trans-4-styrylpyridine)methyl(trioxo)rhenium(VII). Photoassisted isomerization of 4-styrylpyridine

The reflectance spectrum of solid MeReO3(trans-4-styrylpyridine) shows a long-wavelength band (lambda(max) = 342 nm) with vibrational structure. This band is assigned to an intraligand transition of the coordinated styrylpyridine. In solution (e.g. CH2Cl2) the complex largely dissociates into MeReO3 and styrylpyridine which displays a broad absorption at lambda(max) = 308 nm. Irradiation with 366 nm light leads to selective excitation of residual amounts of intact MeReO3(trans-4-styrylpyridine) which undergoes a complete trans-to-cis photoisomerization of the coordinated ligand. Owing to the kinetic lability of MeReO3(trans-4-styrylpyridine) this photolysis proceeds as a photoassisted reaction of 4-styrylpyridine. (C) 1997 Elsevier Science S.A.