Bistable Photochromic Organometallics Based on Linkage Isomerization:Photochemistry of Dicarbonyl(eta~5-methylcyclopentadienyl)manganese(I) Derivatives with a Bifunctional,Nonchelating Ligand

摘要

Cyclopentadienylmanganese complexes of the general formula (eta~5-C_5H_4CH_3)Mn(CO)_2L,where L is a nonchelatable,bifunctional ligand,were found to be photochromic.Irradiation of (eta~5-C_5H_4CH_3)Mn(CO)_2L(3-cyanomethylpyridine) with alternating visible and UV light produced alternating yellow and red solutions,and fatigue of this response was inhibited when free 3-(cyanomethyl)pyridine was present during irradiation.Similar results were observed when L is pyridine in the presence of dispersed acetonitrile.Irradiation of (eta~5-C_5H_4CH_3)Mn(CO)_3 and a pyridine derivative RC_5H_4N (R=3-CH_2CN,2-CH_2CN,4-CHCHPh,4-CHCH_2) generated (eta~5-C_5H_4CH_3)Mn(CO)_2L in situ,which likewise showed a photochromic response.The results demonstrate that the linkage isomerization occurs by unimolecular and bimolecular processes and that linkage isomerization is an effective photochromic mechanism for organometallics.