Dichloro(pentamethylcyclopentadienyl)ruthenium—Novel Dichotomy in a Molecular Structure

Abstract

Dimers with very different RuRu bond lengths and RuClRu bond angles—deformation isomers—are present in equal parts in crystals of the title compound. Solid-state NMR investigations show that the isomer 1 a with the shorter RuRu distance (2.93 Å) is diamagnetic, that with the longer distance (3.75 Å, 1 b), on the other hand, paramagnetic. The temperature dependence of the 1H NMR signal in solution is understandable if one assumes that the two isomers rapidly interconvert.