THE X-RAY STRUCTURE DETERMINATIONS AND SEMIEMPIRICAL PM3 CALCULATIONSOF 2 CHLORO(PIPERIDYL)CYCLOTRI(PHOSPHAZENES)

Single crystals of etrachloro-2,4-bis(piperidyl)cyclotri(phosphazene) (1a) and of ichloro-2,4,6-tris(piperidyl)cyclotri(phosphazene) (2a) we re grown from petroleum ether solution. The structures of both compoun ds were determined by single-crystal X-ray diffraction analyses. Compo und 1a crystallizes in the monoclinic space group P 2(1)/n with Z = 4 and unit cell dimensions a = 9.3994(4), b = 19.204(3), c = 11.5664(4) Angstrom, and beta = 108.718(4)degrees. Compound 2a crystallizes in th e triclinic space group P (1) over bar with Z = 4 and unit cell dimens ions a = 12.8289(2), b = 13.8856(2), c = 14.63810(10) Angstrom, and al pha = 100.7621(5), beta = 91.0094(2), gamma = 113.9757(6)degrees. The experimentally obtained structural parameters for the covalent molecul es 1a and 2a compare well with those calculated at the semiempirical P M3 level of theory. These results give credence to the PM3 calculated structures of tetraazido-2,4-bis(piperidyl)cyclotri(phosphazene) (1b) and riazido-2,4,6-tris(piperidyl)cyclotri(phosphazene) (2b) for which presently there are no experimental data available.dagger. (C) 1997 Jo hn Wiley & Sons, Inc.