First cupracarborane commo-clusters based on the medium-cage nido-5,6-C2B8H12-carborane and molecular structure of [Ph3PEt][commo-9,9′-Cu(nido-7,8-C2B8H11)2]

A reaction of anhydrous CuCl2 with Na salts of the medium-cage carborane [7-X-nido-5,6-C2B8H10]−(X = H or I) derivatives in THF leads to new cupracarborane commo-clusters, [commo-9,9′-Cu(nido-7,8-C2B8H11)2]− and [commo-9,9′-Cu(11-I-nido-7,8-C2B8H10)2]−, in moderate yields. The clusters were isolated as stable [Ph3PEt]+ salts and characterized by 1H, 31P{1H}, and 11B/11B{1H} NMR spectroscopy and X-ray crystallography (for the unsubstituted derivative). The use in this reaction of the reducing agent Na2SO3 considerably increases the yields of both complexes from 25 and 18% to 74 and 68%, respectively.