856255-17-9Relevant academic research and scientific papers
Synthesis, reactivity and structural studies of carboranyl thioethers and disulfides
Laromaine, Anna,Teixidor, Francesc,Kivekaes, Raikko,Sillanpaeae, Reijo,Benakki, Rajae,Gruener, Bohumir,Vinas, Clara
, p. 1785 - 1795 (2007/10/03)
The equimolar reaction of 1-SH-2-R-1,2-closo-C2B 10H10 (R = Me, H, Ph) with KOH in ethanol produces the thiolate species [1-S-2-R-1,2-closo-C2B10H 10]-. These react with iodine to give the disulfide bridged dicluster (1-S-2-R-1,2-closo-C2B10H 10)2 (R = H, Me, Ph) compounds as analytically pure, white and air-stable solids in high yield. Synthesis of monothioether bridged species is synthetically more difficult. In fact three procedures have been tested to obtain the thioether bridged dicluster compounds (2-R-1,2-closo-C 2B10H10)2S (R = Me, H, Ph) but only (2-Me-1,2-closo-C2B10H10)2S was successfully synthesized and characterized. Attempts to produce mixed compounds (1-R-1,2-closo-C2B10H10)S(1-R′-1,2-closo- C2B10H10), R ≠ R′, were unsuccessful. Deboronation reaction of this dicarboranylthioether lead, depending on the reaction conditions, to monoanionic [(2-Me-1,2-closo-C2B 10H10)S(8-Me-7,8-nido-C2B9H 10]- or dianionic [(8-Me-7,8-nido-C2B 9H10)2S]2- sulfur bridge anions. Deboronation of carboranyl disulfides gave the corresponding dianionic [(7-S-8-R-7,8-nido-C2B9H10)2] 2- (R = H, Me, Ph) species. This reaction was very dependent, however, on the reaction conditions. With slight variation of the reaction conditions, splitting of the S-S bond leading to the thiolate species with retention of the closo cluster was also found. Carboranyl disulfides (1-S-2-R-1,2-closo-C2B10H10)2 (R = H, Me, Ph) do not lead to thiosulfinates R-S(O)-S-R′ by oxidation with H2O2 or I2 as organic disulfides do. This behaviour is attributed to the presence of the sulfur atom directly bonded to the carbon cluster that produces electronic transfer from the filled orbitals on the sulfur atom into the cage LUMO (largely located on the cage C c-CC bond). This causes a depletion of electron density on the sulfur, thence impairing sulfur oxidation, and facilitating S-S breaking. Crystal structures of monothioethers (2-Me-1,2-closo-C2B 10H10)2S, [NMe4][(2-Me-1,2-closo- C2B10H10)S(8-Me-7,8-nido-C2B 9H10)] (the first example reported in the literature of a two cluster compound incorporating the closo C2B10 and the nido [C2B9]- moieties linked by a one member spacer) and disulfides (1-S-1,2-closo-C2B10H 11)2, (1-S-2-Me-1,2-closo-C2B 10H10)2, (1-S-2-Ph-1,2-closo-C 2B10H10)2 are reported which support the behaviour of these species. The Royal Society of Chemistry 2005.
