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RESEARCH PRODUCT

Recent studies on RR′S·C2B9H11 charge-compensated ligands

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Abstract In this paper we report the synthesis of three new carborane derivatives of the series 7,8-R,R′-10-L-7,8-C2B9H9 (R=R′=H, L=SEtPh; R=CH3, R′=H, L=SMe2 and L=SEt2) along with the enhanced characterization of formerly described compounds 7,8-R,R′-10-L-7,8-C2B9H9 (R=R′=H, L=SMe2 (1), L=SEt2 (2) and L=S(CH2)4 (3)). They have been fully characterised using 1H-, 11B- and 13C-NMR spectroscopy. Their bridging proton resonances have been located for the first time. Individual sulfonium substituent contributions have been calculated that have permitted to establish a rule to predict its position in the 1H-NMR spectrum. The crystal structures of 1 and 3 have been resolved for the first time. Thermolysis of 1, 2 and 3 in aromatic solvents at reflux temperature yielded a mixture of the corresponding 9-substituted derivative via isomerisation and 2,3-closo-C2B9H11 via elimination of SR2. This reaction has been demonstrated to be tuneable upon convenient choice of the aromatic solvent, the ligand and the reaction time, leading to a new and more straightforward preparation of the series 9-L-7,8-nido-C2B9H11 and the cluster 2,3-closo-C2B9H11.