Position-dependent deuterium isotope effect on photoisomerization of ammineaquarhodium(III) complexes: identification of the excited-state vibronic deactivation mode

Abstract

cis to trans Photoisomerization quantum yields are increased by a factor of approximately tow by deuteriation of co-ordinated water in tetra-amminediaquarhodium(III), but are almost insensitive to deuteriation of co-ordinated water in tetra-ammineaquachlororhodium(III) and to deuteriation of co-ordinated ammonia in either complex; this identifies the dominating nonradiative deactivation mode (competing with the excited-state rearrangement) as a hydrogen–oxygen vibration in an excited-state intermediate of reduced co-ordination number.