Treatment of the isomeric 12-vertex nickelacarbaborane salts [NEt(4)][3-(eta3)-C(3)H(5))-closo-3,1,2-NiC(2)B(9)H(11)] and [NEt(4)][2-(eta3)-C(3)H(5))-closo-2,1,7-NiC(2)B(9)H(11)] with [CuCl(PPh(3))](4) and Tl[PF(6)] affords the zwitterionic bimetallic species [3-(eta3)-C(3)H(5))-3,4,8-[Cu(PPh(3))]-4,8-(mu-H)(2)-closo-3,1,2-NiC(2)B(9)H(9)] and [2-(eta3)-C(3)H(5))-2,6,11-(Cu(PPh(3)))-6,11-(mu-H)(2)-closo-2,1,7-NiC(2)B(9)H(9)], respectively. Similarly, the 13-vertex nickelacarbaborane [NEt(4)][4-(eta3)-C(3)H(5))-closo-4,1,6-NiC(2)B(10)H(12)] reacts with sources of mono-cationic metal fragments to form [4-(eta3)-C(3)H(5))-7,8,13-(Cu(PPh(3)))-7,8,13-(mu-H)(3)-4,1,6-closo-NiC(2)B(10)H(9)], [4-(eta3)-C(3)H(5))-3,8-(Rh(PPh(3))(2))-3,8-(mu-H)(2)-4,1,6-closo-NiC(2)B(10)H(10)] and [4-(eta3)-C(3)H(5))-3,7,8-(RuCl(PPh(3))(2))-3,7,8-(mu-H)(3)-4,1,6-closo-NiC(2)B(10)H(9)]. The molecular structures of these five new bimetallic compounds were determined by X-ray diffraction studies, confirming that exopolyhedral Cu, Rh and Ru fragments are attached to the cluster via B-H[right harpoon up]M agostic-type interactions and, in the case of the (NiC(2)B(9)) species, by a metal-metal bond.