Cobaltaborane analogs of decaborane (B10H14). Crystal and molecular structures of 6-[.eta.5-C5(CH3)5]CoB9H13, 6,9-[.eta.5-C5(CH3)5]2]2Co2B8H12, 5,7-[.eta.5-C5(CH3)5]5]2Co2B8H12, and 6-Cl-5,7-[.eta.5-C5(CH3)5]2Co2B8H11