Facile two-electron reduction of a closo-rhodathiadecaboraneDedicated to Professor David Cole-Hamilton on the occasion of his retirement and for his outstanding contribution to transition metal catalysis.Electronic supplementary information (ESI) available: DFT-calculated coordinates for 3, 4 and 5; kinetic data; cif files. CCDC 891149-891151. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2dt31465g

Closo -to- arachno redox flexibility in metallaheteroboranes may be viewed as a metal-to-ligand cooperative action with application in catalysis. The treatment of [PSH][ arachno -4-SB 8 H 11 ] with [RhCl(PPh 3 ) 3 ] affords, after chromatography, three new 10-vertex rhodathiaboranes, [2,2,2-(H)(PPh 3 ) 2 - closo -2,1-RhSB 8 H 8 ] ( 3 ), [6,6,9-(PPh 3 ) 3 - arachno -6,5-RhSB 8 H 9 ] ( 4 ) and [2,2,2-(Cl)(H)(PPh 3 )-6-(PPh 3 )- closo -2,1-RhSB 8 H 7 ] ( 5 ). 3 reacts quantitatively with PPh 3 to form 4 , which, in turn, reacts with chlorinated solvents to give the chloro-ligated cluster 5 . Kinetic studies demonstrate that the reaction of 3 with PPh 3 obeys a second-order rate law, with an associative mechanism. The Lewis acidity of 3 is quite remarkable, and, given its closo -to- arachno structural and electronic response, this cluster is expected to exhibit a rich chemistry. Three new 10-vertex rhodathiaboranes are sequentially formed in the reaction between [ arachno -4-SB 8 H 11 ] and [RhCl(PPh 3 ) 3 ]. This stepwise reactivity and the resulting closo arachno closo structural and electronic response augurs a rich chemistry.