ISOLATION AND CHARACTERIZATION OF AN INDIUM MIXED-PNICOGEN 4-MEMBERED-RING COMPOUND - CRYSTAL-STRUCTURE OF (ME3SICH2)2INAS(SIME3)2IN(CH2SIME3)2P(SIME3)2

The first four-membered ring containing two indium atoms with bridging by two different group 15 elements, (Me3SiCH2)sInAs(SiMe3)sIn(CH2SiMe 3)2P(SiMe3)2(1), to be characterized completely was prepared by the eq uilibration of [(Me3SiCH2)sInP(SiMe3)2]2 (2) With [(Me3SiCH2)2InAs(SiM e3)2]2 (3) in a 1:1 mole ratio. X-ray crystallographic analysis showed the In-As-In-P ring of 1 to be planar. Crystals of 1 belong to the or thorhombic system, space group Pbcn (D2h14), with four molecules in a unit cell of dimensions a = 12.848(l) angstrom, b = 21.558(l) angstrom , and c = 18.736(1) angstrom and are isomorphous with those of 2 and 3 . The electron ionization (20 e V) mass spectrum of 1 shows a fragment ation pattern indicative of this compound and no peaks above m/z 510 c onsistent with either 2 or 3. Clusters assigned to specific ions in th e mass spectrum show appropriate isotopic patterns as calculated for t he atoms present.