Diaquabromo(18-crown-6)rubidium and triaqua(18-crown-6)barium dibromide monohydrate: Synthesis and crystal structures
Tóm tắt
Two complexes are synthesized: diaquabromo(18-crown-6)rubidium [RbBr(18-crown-6)(H2O)2] (I) and triaqua(18-crown-6)barium dibromide monohydrate [Ba(18-crown-6)(H2O)3]2+ 2Br− · H2O (II). The orthorhombic structure of compound I (space group Pnma, a = 10.124 Å, b = 15.205 Å, c = 12.544 Å, Z = 4) and the monoclinic structure of compound II (space group C 2/c, a = 17.910 Å, b = 10.315 Å, c = 14.879 Å, β = 123.23°, Z = 4) are determined by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.063 (I) and 0.042 (II) for all 2293 (I) and 3363 (II) independent measured reflections (CAD-4 automated diffractometer, λMoK
α). The complex molecule [RbBr(18-crown-6)(H2O)2] in compound I and the randomly disordered cation [Ba(18-crown-6)(H2O)3]2+ in compound II are of the host-guest type: their Rb+ or Ba2+ cation (its coordination number is nine) is located in the cavity of the 18-crown-6 ligand and coordinated by all six O atoms. In structure I, the coordination polyhedron of Rb+ is a distorted hexagonal pyramid with a triple apex at the Br− ligand and two O atoms of the water molecules. In structure II, the Ba2+ polyhedron is a distorted hexagonal bipyramid with one apex at the O atom of the water molecule and the other split apex at two O atoms of water molecules.
Tài liệu tham khảo
M. Hiraoka, Crown Compounds. Their Characteristics and Applications (Elsevier, Amsterdam, 1982; Mir, Moscow, 1986.
Host Guest Complex Chemistry, Ed. by F. Vögtle and E. Weber (Springer, New York, 1985; Mir, Moscow, 1988).
O. Nagano, A. Kobayashi, and Y. Sasaki, Bull. Chem. Soc. Jpn. 51(3), 790 (1978).
A. N. Chekhlov, Zh. Neorg. Khim. 50(3), 477 (2005) [Russ. J. Inorg. Chem. 50 (3), 418 (2005)].
A. N. Chekhlov, Zh. Neorg. Khim. 2008 (in press).
A. C. T. North, D. C. Phillips, and F. S. Mathews, Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 24(3), 351 (1968).
G. M. Sheldrick, The SHELX97 Manual (Univ. of Göttingen, Gottingen, 1997).
International Tables for Crystallography (Kluwer, Dordrecht, 1992), Vol. C.
R. D. Shannon, Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 32(5), 751 (1976).
L. Pauling, The Nature of the Chemical Bond (Cornell Univ. Press, Ithaca, 1960).
A. Bondi, J. Phys. Chem. 68(3), 441 (1964).
F. H. Allen, O. Kennard, D. G. Watson, et al., J. Chem. Soc., Perkin Trans., No. 12, 2 (1987).
E. Maverick, P. Seiler, W. B. Schweizer, and J. D. Dunitz, Acta Crystallogr., Sect. B 36(3), 615 (1980).
J. Van Eerden, S. Harkema, and D. Feil, Acta Crystallogr., Sect. B 46(2), 222 (1990).