THE CHEMISTRY OF THE BIS(pi-(3)-1,2-DICARBOLLYL) METALLATES OF NICKEL AND PALLADIUM.

The synthesis, reactions, and structures associated with the sandwich-bonded bispi-3-1,2-dicarbollyl complexes of nickel and palladium, Mn1,2-B9C2H112n-4MNi,Pd, and their carbon-substituted derivatives are discussed. The nickel and palladium bisdicarbollyl systems each contain species with the metal atoms in the formal 2 d8, two unpaired electrons for nickel, diamagnetic for palladium, 3 d7, one unpaired electron, and 4 d6, diamagnetic oxidation states. X-ray diffraction studies coupled with magnetic, spectral, and electrochemical data were obtained for structural information. The uncharged pi-3-1,2-B9C2H112MIV derivatives are Lewis acids which form addition compounds with a variety of soft Lewis bases, e.g., halide ions, thiocyanate ion, naphthalene, etc. The C, C-dimethyl-substituted nickel and palladium systems, M1,2-B9H9C2CH322, exhibit facile thermal ligand rearrangement reactions leading to three isomeric series of complexes. In these isomerization reactions, a ligand carbon atom in the icosahedral surface was found to migrate away from the metal atom while remaining adjacent to the carbon atom in the open pentagonal face of the ligand. Similar rearrangements occur in the unsubstituted Ni1,2-B9C2H112 complex at 360-400C in the vapor phase. Cyclic voltammetry, optical resolution studies, kinetic and nmr data and their roles in the structure elucidation of these complexes are presented. Author