Three-dimensional metal piperazinyldiphosphonate phases with ellipsoidal cavities defined by 44-membered rings: Crystal structures of [M{O3PCH2NH(C2H4)(2)NHCH2PO3}]center dot H2O, M=Mn and Co

The hydrothermal reaction of a mixture of (Et(4)N)(2)MnCl4, N,N'-piperazinebis(methylenephosphonic acid), Et(4)NCl . H2O, and H2O in the mole ratio 1:1:5:300, adjusted to pH 5 with 40% aqueous (Bu(4)N)OH, at 160 degrees C for 63 h yielded [Mn{O3PCH2NH(C2H4)(2)NHCH2PO3}]. H2O (1) in 60% as off-white platelets. The analogous reaction using (Et(4)N)(2)COCl4 produced [Co{O3PCH2NH(C2H4)(2)NHCH2PO3}]. H2O (2). The isomorphous materials 1 and 2 display three-dimensional network structures, based on binuclear units of corner-sharing metal and phosphorus tetrahedra, forming eight membered {-Co-O-P-O-}(2) rings, The diphosphonate groups serve to tether the binuclear units into large ellipsoidal 44-membered rings. As the piperazinyl nitrogen atoms are protonated, the organic moiety of the disphosphonate group serves as both tether and charge compensating site. Compound 1 exhibits Curie-Weiss paramagnetism with weak antiferromagnetism between Aln centers. In contrast, the susceptibility of 2 exhibits a broad maximum at low temperatures consistent with short range anti-ferromagnetic coupling. Crystal data: 1, C6H16MnN2O7 P-2, triclinic <P(1)over bar>, a = 8.393(2) Angstrom, b = 9.043(2) Angstrom, c = 9.125(2) Angstrom, alpha = 62.88(3)degrees, a = 62.88(3)degrees, beta = 86.36(3)degrees, gamma = 78.96(3)degrees, V = 604.8(3) Angstrom(3); R = 0.056 for 1663 reflections. 2, C6H16 CoN2O7P2, triclinic <P(1)over bar>, a = 8.340(2) Angstrom, b = 8.917(2) Angstrom, c = 9.018(2) Angstrom, alpha = 64.11(3)degrees, beta = 86.24(3)degrees, gamma = 78.87(3)degrees, V = 591.9(2) Angstrom(3); R = 0.083 for 1917 reflections. (C) 1996 Academic Press, Inc.