Synthesis and structural characterisation of the trinuclear barium disiloxanes [Ba 3 (OSiPh 2 OSiPh 2 O) 3 (tetraglyme) 2 ] and [Ba 3 (OSiPh 2 OSiPh 2 O) 3 (hmpa) 5 (H 2 O)], containing an unusual Ba 3 O 7 core [tetraglyme = Me(OCH 2 CH 2 ) 4 OMe; hmpa =(Me 2 N) 3 PO]

Barium granules react with diphenylsilanediol in a mixed ammonia–toluene solution at –40 °C to yield [Ba(OSiPh2OSiPh2O)(H2O)(NH3)0.33]1, addition of either tetraglyme or hexamethylphosphoramide (hmpa) produces [Ba3(OSiPh2OSiPh2O)3(tetraglyme)2]2 and [Ba3(OSiPh2OSiPh2O)3(hmpa)5(H2O)]3, respectively; complexes 2 and 3 are the first X-ray structurally characterised barium disiloxanes and contain an unusual trinuclear array of Ba cations incorporating an identical Ba3O7 core.