IR study of rotational isomerism in dirhenium and diruthenium complexes ofthe ferrole type

A novel type of rotational isomerism was found in binuclear dirhenium compl ex of ferrole type Re-2(CO)(7)(C(8)H(7)Ph(2)Fc(2)) (II) by Fourier transfor m IR spectroscopy in a wide temperature range (165-293 K) in pentane and li quid xenon solutions. The conformers result from internal rotation of a met al carbonyl moiety about the multicentred bond involving another metal carb onyl fragment. According to IR and Raman spectroscopy, the diruthenium comp lex Ru-2(CO)(6){C(4)Fc(2)(C equivalent to CFc)(2)} (III) exists in the soli d state and in solution as two different conformers. In the solid state the 'non-sawhorse' conformation with the semibridging carbonyl group was found , which transforms in solution to the conformation containing only terminal carbonyl groups. (C) 1999 Elsevier Science S.A. All rights reserved.