SYNTHESIS AND CRYSTAL-STRUCTURE OF A CESIUM HYDROGEN BENZOYLCYANOXIMATE COMPLEX WITH 18-CROWN-6 - CS(18-CROWN-6)(H(L)(2))

The caesium hydrogen benzoylcyanoximate (L-) complex with 18-crown-6 o f composition Cs(18-crown-6){H(L)(2)} has been prepared and studied by means of X-ray diffraction [monoclinic, space group P2(1)/n, with a = 9.906(1), b = 18.387(3), c = 18.855(3) Angstrom, beta = 90.13(1)degre es, V = 3434.3(9) Angstrom, Z = 4; final R1 = 0.043 for the 6431 indep endent reflections used. The lattice consists of Cs(18-crown-6)(+) cat ions and complex hydrogen oximate anions {H(L)(2)}(-), formed via stro ng hydrogen bonding between the oxygen atoms of nitroso-groups [O---O ca. 2.456(5) Angstrom]. The caesium atom deviates by 1.492(3) Angstrom from the mean plane of the oxygen atoms of the macrocyclic ether (dom inant orientation of disordered ligand, 60%) and adopts a typical ''su nrise coordination'' [Cs-O (ether) 3.040(9)-3.312(7) Angstrom]. The hy drogen oximate groups are bonded to the metal center only on one side of the crown ether plane via the oxygen atoms of nitroso-groups and th e nitrogen atoms of cyano groups (Cs-O ca. 3.040(9), 3.312(7) Angstrom ; Cs-N ca. 3.469(5), 3.679(6) Angstrom). The coordination polyhedron o f Cs+ can be described as a distorted bicapped tetragonal prism.