SYNTHESIS AND CHARACTERIZATION OF NOVEL METALLOCARBORANE TRIPLE-DECKER COMPLEXES

The syntheses of two novel triple-decker complexes are described where the [C2B9H11]2- dianion is utilized for the first time as a terminal ligand. The sandwich anion [Co(C5H5) (C3B2MeEt4)]- (C3B2MeEt4 = traeth yl-1H-2.3-dihydro-2-methyl-1,3-diborol-2-yl) reacts with the [C2B9H11] 2- dianion and bis(pentane-2,4-dionato)nickel(II) to give the symmetri cal tetradecker complex [Ni{(C3B2MeEt4)-Co(C5H5)}2] and the two unsymm etrical triple-decker complexes [(C5H5)Co(C3B2MeEt4)Ni(C2B9H11)] and [ (C5H5)Co(C3B2MeEt4)Co(C2B9H11)]. The molecular structures of the three complexes were established from elemental analyses and H-1 and B-11-{ H-1} NMR and mass spectroscopic studies. In addition, the single-cryst al X-ray analyses of the unsymmetrical ones were performed. Both compl exes crystallize in the orthorhombic space group P2(1)2(1)2(1) (no. 19 ) with cell dimensions: for CoNi, a = 10.077(4), b = 13.880(1), c = 18 .318(2); for CoCo, a = 9.973(3), b = 13.885(3), c = 18.280(5) angstrom . The CoCo triple-decker was also synthesised in higher yield from the reaction of the [Co(C5H5)(C3B2MeEt4)]- anion with the [C2B9H11]2- dia nion and cobalt(II) chloride. The redox properties of the triple-decke r complexes were studied by cyclic voltammetry.