445462-17-9Relevant academic research and scientific papers
Unprecedented cage-carbon to cage-boron NMe3 transfer in a monocarbon molybdenacarborane
Du, Shaowu,Kautz, Jason A.,McGrath, Thomas D.,Stone, F. Gordon A.
, p. 3202 - 3211 (2002)
The reagent Li2[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 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, a feature established spectroscopically in 1 and 2, and by X-ray diffraction studies on several of their derivatives. When [Rh(NCMe)3(η5-C5 Me5)][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-C5 Me5)2}-closo-2,1-MoCB10H9] (10) is formed, the NMe3 group being lost. Reaction of 1 in CH2Cl2 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 products obtained, [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 by B-X. In contrast, treatment of 2 with I2 and cyclo-1,4-S2(CH2)4 in CH2Cl2 results in oxidative substitution of the cluster and retention of the NMe3 group, giving [2,2,2-(CO)3-2-3-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 studies upon 6, 7, 9 and 10.
