The crystal structures of the complexes formed by benzo-18-crown-6 with barium perchlorate and with strontium perchlorate, bisperchloratobisaquo(6, 7, 9, 10, 12, 13, 15, 16, 18, 19 decahydro benzo [b]-1, 4, 7, 10, 13, 16 hexaoxacyclooctadecin)- barium and trisaquo(6, 7, 9, 10, 12, 13, 15, 16, 18, 19 decahydrobenzo [b]-1, 4, 7, 10, 13, 16 hexaoxacyclooctadecin)strontium diperchlorate

Abstract

Abstract The crystal structures of the title compounds have been determined by X-ray diffraction. In the barium compound the cation is coordinated by 10 oxygen atoms, six from the crown ether ring (BaO 2.802–2.846 A), two water molecules (BaO 2.780, 2.843 A) and one oxygen atom from a perchlorate ion (BaO 2.937 A) on one side of the ring and one oxygen atom from the second perchlorate ion on the other side of the ring (BaO 2.794 A). The neutral complexes are held in the ab plane by water⋯perchlorate hydrogen bonds. In the strontium compound there are separate perchlorate ions, and complex cations having strontium in 9 coordination by six oxygen atoms from the crown ether ring (SrO 2.662–2.723 A), two water molecules on one side of the ring (SrO 2.578, 2.574 A) and one water molecule on the other (SrO 2.553 A). Each water molecule forms hydrogen bonds to two perchlorate ions; three of the four oxygen atoms of each anion (mean ClO 1.42 A) accept one hydrogen bond, the fourth oxygen has a shorter ClO distance, mean 1.38 A. For the barium compound a = 14.030(5), b = 18.828(7), c = 9.844(7) A, β = 99.08(2)°, space group P21/a, Z = 4 Ba(benzo-18-crown-6)ClO4)2(H2O)2. Observations were collected with Mo-Kα radiation on a 4-circle diffractometer: after full-matrix least-squares refinement, R = 0.059 for 2751 measured reflections. For the strontium compound a = 11.237(3), b = 21.487(6), c = 10.908(3) A, β = 93.68(2)°, space group P21/n, Z = 4 Sr(benzo-18-crown-6)(ClO4)2(H2O)3. Observations were collected with Cu-Kα radiation on a kappa geometry diffractometer; after full-matrix least-squares refinement R = 0.079 for 3899 observed reflections.