The reagent Li-2[7-NMe3-nido-7-CB10H10] reacts with [Mo(CO)(3)(NCMe)(3)] in THF-NCMe (THF = tetrahydrofuran) to give a molybdenacarborane intermediate which, upon oxidation by CH2=CHCH2Br or 12 and then addition of [N(pph(3))(2)]-Cl, gives the salts [N(PPh3)(2)][2,2,2-(CO)(3)-2-X-3-NMe3-closo-2,1 -MoCB10H10] (X = Br (1) or I (2)). During the reaction, the cage-bound NMe3 substituent is transferred from the cage-carbon atom to an adjacent cage-boron atom, a feature established spectroscopically in 1 and 2, and by X-ray diffraction studies on several of their derivatives. When [Rh(NCMe)(3)(eta(5)-C5Me5)][BF4](2) is used as the oxidizing agent, the trimetallic compound [2,2,2-(CO)(3)-7-mu-H-2,7,11-{Rh-2(mu-CO)(eta(5)-C5Me5)(2)}-closo-2,1-MoCB10H9] (10) is formed, the NMe3 group being lost. Reaction of 1 in CH2Cl2 with TI[PF6] in the presence of donor ligands L affords neutral zwitterionic compounds [2,2,2-(CO)(3)-2-L-3-NMe3-c/oso-2,1-MoCB10H10] for L = PPh3 (4) or CNBut (5), and [2-(BuC)-C-t=-CH-2,2-(CO)(2)-3-NMe3-closo-2,1-MoCB10H10] (6) when L = Bu(t)CdropCH. When 1 is treated with CNBut and X-2, the metal center is oxidized, and in the products obtained, [2,2,2,2-(CNBut)(4)-2-Br-3-X-closo-2,1-MoCB10H10] (X = Br (7), 1 (8)), the B-NMe3 bond is replaced by B-X. In contrast, treatment of 2 with I-2 and cyclo-1+S-2(CH2)(4) in CH2Cl2 results in oxidative substitution of the cluster and retention of the NMe3 group, giving [2,2,2-(CO)(3)-2-1-3-NMe3-6-{cyclo-1,4-S-2(CH2)(4)}-closo-2,1-MoCB10H9] (9). The unique structural features of the new compounds were confirmed by single-crystal X-ray diffraction studies upon 6, 7, 9 and 10.