Adducts of o-silaborane with water and methanol

The synthesis of alkoxide adducts of o-silaborane [(TMPDAH)(2)][(Me2Si2B10H 10)(2)O] (3) and [TMPDAH][(Me2Si2B10H10)OMe] (4) are presented (TMPDA = tet ramethylpropylenediamine). For both silaborate clusters 3 and 4 the results of the NMR spectroscopic investigations together with the X-ray single cry stal structure determinations are discussed. The geometries of ab initio ca lculations (HF and B3LYP methods) on the hydroxide adduct [Si2B10H12(OH)](- ) are compared with the structures of 3 and 4. The dynamic behaviour of the adducts 3 and 4 in solution is discussed with respect to the calculated en ergy profile for the rotation of the HSi(OH) group.