| Abstract
| - The anions [2,2,2-(CO)3-2-X-3-NMe3-closo-2,1-MoCB10H10]- (X = Br, I) (shown) have a B−NMe3 substituent yet are formed from a C−NMe3 precursor.
- The reagent Li2[7-NMe3-nido-7-CB10H10] reacts with [Mo(CO)3(NCMe)3] in THF−NCMe (THF = tetrahydrofuran) togive a molybdenacarborane intermediate which, upon oxidation by CH2CHCH2Br or I2 and then addition of [N(PPh3)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, afeature established spectroscopically in 1 and 2, and by X-ray diffraction studies on several of their derivatives.When [Rh(NCMe)3(η5-C5Me5)][BF4]2 is used as the oxidizing agent, the trimetallic compound [2,2,2-(CO)3-7-μ-H-2,7,11-{Rh2(μ-CO)(η5-C5Me5)2}-closo-2,1-MoCB10H9] (10) is formed, the NMe3 group being lost. Reaction of 1 inCH2Cl2 with Tl[PF6] in the presence of donor ligands L affords neutral zwitterionic compounds [2,2,2-(CO)3-2-L-3-NMe3-closo-2,1-MoCB10H10] for L = PPh3 (4) or CNBut (5), and [2-ButC⋮CH-2,2-(CO)2-3-NMe3-closo-2,1-MoCB10H10](6) when L = ButC⋮CH. When 1 is treated with CNBut and X2, the metal center is oxidized, and in the productsobtained, [2,2,2,2-(CNBut)4-2-Br-3-X-closo-2,1-MoCB10H10] (X = Br (7), I (8)), the B−NMe3 bond is replaced byB−X. In contrast, treatment of 2 with I2 and cyclo-1,4-S2(CH2)4 in CH2Cl2 results in oxidative substitution of thecluster and retention of the NMe3 group, giving [2,2,2-(CO)3-2-I-3-NMe3-6-{cyclo-1,4-S2(CH2)4}-closo-2,1-MoCB10H9](9). The unique structural features of the new compounds were confirmed by single-crystal X-ray diffraction studiesupon 6, 7, 9 and 10.
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