Formation, structure, and reactivities of 1:1 adducts between quadricyclane and (η5-cyclopentadienyl)(1,2-diphenyl- or -dimethoxycarbonyl-1,2-ethenedithiolato)rhodium(III)

Abstract The rhodiadithiolene complexes [Rh(Cp)(S 2 C 2 Z 2 )] (Z=Ph ( 1a ) and COOMe ( 1b )) reacted with quadricyclane (Q) to give 1:1 adducts [Rh(Cp)(S 2 C 2 Z 2 ) (C 7 H 8 )] (Z=Ph ( 2a ) and COOMe ( 2b )) in which Rh and S of the complexes are bridged by C(7) (bridge carbons) and C(5) (edge carbons) of norbornene (C 7 H 8 ), respectively. The structure of the adduct 2a was re-investigated and determined by X-ray structural analysis. The rhodiadithiolene complexes and those adducts showed the catalytic activities for the thermal isomerization from Q to norbornadiene (NBD). Adduct 2a photochemically dissociated to give the original complex 1a and NBD upon irradiation with a high-pressure mercury lamp. Skeletal rearrangements of the hydrocarbon moiety were confirmed in the formation of these adducts and in their photo-dissociation, according to deuterium labeling experiments.