STRUCTURAL CHARACTERIZATION OF A SERIES OF CYCLOHEXAPHOSPHATES - CA(2)M(2)P(6)O(18)CENTER-DOT-6H(2)O (M=K, TL, RB)

Three new cyclohexaphosphates with the general formula Ca(2)M(2)P(6)O( 18). 6H(2)O (M = K, Tl, Rb) are reported. They crystallize with monocl inic unit cells and are isotopic. As an example the paramters of Ca2K2 P6O18. 6H(2)O are a = 7.266(1), b = 11,833(2), c = 12.300(2) Angstrom, beta = 103.17(1)degrees, Z = 2, P2(1)/n, V = 1030(3) Angstrom(3), and Dr = 2.387 g cm(-3), Crystal structure of this phase was determined u sing 6292 independent reflections with a final R = 0.025, The atomic a rrangement can be described as puckered layers containing water bonded P6O18 anions and Ca2+ and K+ cations, alternating along the (1, 0, 1) direction, Synthesis and characterization by X-ray diffraction, IR ab sorption, and TA are described. (C) 1996 Academic Press, Inc.