An efficient synthesis of 12-vertex closo-rhodacarboranes [3-(η5-C5Me5)-1-R1-2-R2-3,1,2-closo-RhC2B9H9] (R1, R2 = H, Alk) via two-step reactions of [K][7-R1-8-R2-7,8-nido-C2B9H10] mono-anions with [Rh2(η5-C5Me5)2Cl4]: structural characterization of the fi

The room temperature reactions between [Rh2(η5-C5Me5)2Cl4] (1) and [K][7-R1-8-R2-7,8-nido-C2B9H10] (2a–d: a, R1 = R2 = H; b, R1 = R2 = Me; c, R1 = H, R2 = PhCH2; d, R1 = R2 = PhCH2) in solution of C6H6–EtOH mixture (4:1) to give [3-(η5-C5Me5)-1-R1-2-R2-3,1,2-closo-RhC2B9H9] (3a–d), respectively, have been shown to proceed through the formation of the first step ionic intermediates of the type [(η5-C5Me5)Rh(μ-Cl)3Rh(η5-C5Me5)][7-R1-8-R2-7,8-nido-C2B9H10] (4a–d). All ionic compounds 4a–d were isolated in the solid state and characterized by a combination of analytical, IR and multinuclear NMR data, including a single-crystal X-ray diffraction study of 4d. The structure of 3d (R1 = R2 = PhCH2), the first 12-vertex closo-type metallacarborane species bearing sterically demanding C,C′-dibenzylsubstituted carborane ligand, has also been determined by an X-ray crystallography.