Metallacarborane clusters based on the middle-cage carborane [5,6-nido-C2B8H12]. Synthesis and the thermal isonido-to-closo rearrangement of the anionic complex [PPN][commo-1,1′-Rh(7-MeO-isonido-2,4-C2B8H9)-(isonido-2,4-C2B8H10)

Abstract

The reaction of the middle-cage carborane 5,6-nido-C2B8H12 with the dimeric rhodium complexes [(η2-C8H14)2RhCl]2 or [(η4-C8H12)RhCl]2 in a MeOH/C6H6 mixture gave the anionic commo-rhodacarborane [PPN][commo-1,1′-Rh(isonido-2,4-C2B8H10)2] (as a mixture of meso and dd/ll isomers) and its 7-B-methoxylated derivative [PPN][commo-1,1′-Rh(7-MeO-isonido-2,4-C2B8H9)(isonido-2,4-C2B8H10)] in moderate yields. The latter was subjected to the thermal isonido-to-closo rearrangement to form the new commo-cluster [PPN][commo-1,1′-Rh(closo-2,3-C2B8H9OMe)(closo-2,3-C2B8H10)]. The newly synthesized compounds were characterized by NMR spectroscopy and X-ray diffraction.