MOLECULAR AND CRYSTAL-STRUCTURE OF BIS(MU-ACETATO)-BIS(NORBORNADIENE)DIRHODIUM(I) - CATALYST FOR THE ISOMERIZATION OF QUADRICYCLANE TO NORBORNADIENE

Bis(M-acetato)-bis(norbornadiene)dirhodium(I) has been structurally characterized. The compound has been shown to be an active catalyst for the isomerization of quadricyclane to norbornadiene. This material crystallizes in the centrosymmetric monoclinic space group P21/c with unit cell constants (T = 20 °C) a = 9.7733 (10) Å, b = 15.2859 (15) Å, c = 12.1815 (14) Å, and β = 103.563 (8)°. All 3151 unique reflections were used in the X-ray structure analysis which refined to an RF of 0.028. The Rh(l)-Rh(2) distance is 3.1050 (7) Å. Each Rh atom is bonded to the two olefin moieties of a norbornadiene ligand and to two oxygen atoms of the bridging acetate ligands. Each Rh coordination sphere has an approximate square-planar configuration with average Rh-olefin and Rh-0 distances of 1.975 (4) and 2.106 (7) Å, respectively. The Rh atoms lie 0.098 and 0.157 Å out of their respective coordination planes. The dihedral angle formed between these planes is 50.1°, while the angle between the planes defined only by the Rh and acetate oxygens is 40.2°. Hydrogen atoms on the norbornadiene groups are within van der Waals contact distances, indicative of strong steric interactions between the ligands of the dimer. © 1979, American Chemical Society. All rights reserved.