AN AS2SI3O6 CAGE COMPOUND, 3,3,7,7,10,10-HEXAPHENYL-2,4,6,8,9,11 HEXAOXA-1,5-DIARSA-3,7,10 TRISILABICYCLO-[3.3.3]UNDECANE

The title compound, C36H30As2O6Si3, is the first arsenosilicate compou nd containing tricoordinate arsenic(III) to be studied using X-ray cry stallography. This is also the first structural determination of an ar senosilicate compound with the siloxy moiety acting as a bridging grou p. Two trigonal pyramidal AsO3 units are joined by three tetrahedral - OSiPh(2)O- bridges to form an 11-atom As2Si3O6 cage with mean dimensio ns As-O 1.760(15), Si-O 1.637(5)Angstrom, O-As-O 98.9 (10), O-Si-O 111 .1(4), As-O-Si 139.1(13)degrees.