STRUCTURES OF MOLECULAR ADDUCTS OF INORGANIC SALTS .5. NONCENTROSYMMETRIC 2SR(REO4)(2)CENTER-DOT-3UREA-CENTER-DOT-2 H2O

2 Sr(ReO4)(2) . 3 (NH2)(2)CO . 2 H2O, M = 1308.15. Orthorhombic, a = 1 9.386(2) Angstrom, b = 34.229(4) Angstrom, c = 7.697(2) Angstrom, V = 5107(2) Angstrom(3), space group Fdd2 (No. 43), Z = 8, D-x = 3.402 g . cm(-3), mu(MoKalpha) = 23.25 cm(-1), R = 0.023 for 1144 reflections w ith I > 2 sigma(I). The structure of 2 Sr(ReO4)(2) . 3 Urea . 2 H2O co nsists of (2)(infinity)[M(2)T(4) . 3 Urea]. 2 H2O layers composed of d oubled chalcanthite-like ribbons connected by triple M-O-M (O = urea o xygen atom) bridges and decorated on both sides by ReO4 tetrahedra and water molecules. The layers are held together by II-bonds only. The c oordinate polyhedron of Sr is a highly distorted dodecahedron with Sr- O-ave = 2.603(10) Angstrom. The polyhedra are coupled by sharing a fac e of urea oxygen atoms.