Metallacarborane chemistry of the hypho-[6,7-C2B6H13]− anion: the formation of uniquely structured metallacarboranes image: complete rhodium analogues of arachno-4,6-C2B7H13 and nido-1-CB8H12

Reaction of the tetramethylammonium salt of the hypho -[6,7-C2B6H13]− anion (1) with the [Rh(η5-C5Me5)Cl2]2 dimer in THF solution, resulted in the formation of a novel nine-vertex metalladicarbaborane [5-Cp∗-arachno -5,4,6-RhC2B6H12] (2) (Cp∗ = η5-C5Me5). An analogous reaction, but in the presence of PS (PS = ‘proton-sponge’ = 1,8-bis-(dimethylamino)-naphthalene), resulted in the bimetallic nine-vertex species View the MathML source[2,5-Cp2∗-10-Me-nido-2,5,1-Rh2CB6H9] (3). Compounds 2 and 3 are structural analogues of carboranes arachno-4,6-C2B7H13(4) and nido-1-CB8H12 (5), respectively. The formation of compound 3 is associated with an extrusion of one of the cluster carbon atoms into an exo-polyhedral position and exhibits a very rare nine-vertex nido metallaborane structure with interesting features. Both species 2 and 3 were characterized by multinuclear NMR measurements and single-crystal X-ray diffraction studies.