Brønsted Acid/Base Driven Chemistry with Rhodathiaboranes: A Labile {SB9H9}–Thiadecaborane Fragment System

Reversible H2 cleavage promoted by closo to nido transformations of [1,1-(PPh3)2-3-(NC5H5)-closo-1,2-RhSB9H8] (2)/[8,8,8-(PPh3)2(H)-9-(NC5H5)-nido-8,7-RhSB9H9] (1) is a cooperative action with application in catalysis; the treatment of 2 and [1,1-(PPh3)(CO)-3-(NC5H5)-closo-RhSB9H8] (3) with either HCl or HOTf in CH2Cl2 affords the 11-vertex nido-rhodathiaboranes [8,8-(PPh3)(Cl)-9-(NC5H5)-nido-8,7-RhSB9H9] (4) and [8,8,8-(PPh3)(CO)(Cl)-9-(NC5H5)-nido-8,7-RhSB9H9] (5), respectively. In contrast, the reaction of 1 with triflic acid yields the salt [8,8-(PPh3)2(H)-9-(NC5H5)-nido-RhSB9H10][OTf] (6). These results illustrate the bifunctional nature of the clusters and their nido to closo redox flexibility, which open new routes for the tuning of the reactivity of these polyhedral compounds and widen their potential applications.