Structure of a Cs(l8-crown-6)N(CN)2•H2O complex:: Assembly of the dimeric 2:2 anion paired encapsulate by means of μ2-bridging water molecules

The new macrocyclic complex of composition Cs(18-crown-6)N(CN)(2). H2O has been pre pared and characterized by X-ray crystallography (monoclinic, space group P2(t)/n, with a = 11.218(3), b = 8.563(7), c = 21.704(2) Angstrom; beta = 92.66(1)degrees, V = 2083(2) Angstrom(3), Z = 4; final R = 0.034 and R-w = 0.038 for 2529 independent reflections with I > 3 sigma(I)). The complex adopts a molecular dimeric array [Cs(18c6)(mu(2) H2O){N(CN)(2)}](2)(2:2 anion-paired encapsulate). The dimerization of Cs(18c6)(+) moieties takes place surprisingly not via the nitrilic nitrogen atoms, but via the water molecules (Cs-O 3.139(5), 3.334(5) Angstrom), which is an unprecedented example in the chemistry of M(18c6)(+) complexes. The caesium atom adopts nine-fold coordination (Cs-O (ether) 3.099(5) - 3.280(5) Angstrom). One cyano group of the counter anion completes the coordination environment of the caesium atom (Cs-N 3.420(8) Angstrom), while the second one is involved in hydrogen bonding.