Directed Syntheses Of Cs2- And Cs3-Bridged Decaborane-14 Analogues

To establish a procedure for single-cage cluster expansion of open cage dimetallaoctaboranes(12), we have investigated the chemistry of nido-[(Cp*M)(2)B6H10] (eta(5)-C5Me5 = Cp*, 1: M = Co; 2: M = Rh), with diverse chalcogen-based borate ligands. As a result, treatment of nido-1 and nido-2 with Li[BH2E3] (E = S, Se, or Te) yielded 10-vertex nido-[(Cp*Co)(2)B7EH9] (3: E = S; 4: E = Se; 5: E = Te) along with known 10-vertex nido-[(Cp*M)(2)B6H6E2] (6: E = S, M = Co; 7: E = Se, M = Co; 8: E = Te, M = Co; 9: E = Se, M = Rh). The geometries of dimetallachalcogenaboranes, 3-9, are isostructural with decaborane(14). Thermolysis of nido-1 and nido-2 with an intermediate, generated from CS2 and [LiBH4]center dot THF reaction in THF, produced nido-[(Cp*M)(2)B6S2H4(CH2S2)] (10: M = Co; 11: M = Rh) and nido-[(Cp*M)(2)B6S2H4(CS3)] (12: M = Co; 13: M= Rh). Clusters 10-13 are rare species in which one of the B-B bonds is coordinated with a {CS2}(2-) or {CS3}(2-) ligand, generating di(thioborolane) {B2S2CH2} or di(thioboralane)-thione {B2CS3} moieties. To coordination chemistry of CS2-bridged decaborane(14) analogue nido-10, photolysis was carried out with {M(CO)(5)center dot THF} (M = Mo or W) that led to the isolation of [(Cp*Co)(2)B6S2H4(CH2S2){M(CO)(3)}] (14: M = Mo; 15: M = W), where the {CH2S2} moiety is coordinated with one {M(CO)(5)} moiety in eta(1)-fashion. All the synthesized clusters have been characterized by ESI-mass, multinuclear NMR spectroscopy, and IR spectroscopy and structurally solved by single-crystal XRD. Furthermore, DFT calculations probe the bonding of these CS2- and CS3-bridged decaborane analogues.