Urea-water-anion Lattices Part 1. Crystal structures of (C2H5)4N+X?·(NH2)2CO·2 H2O (X=Cl,Br, CN), an isomorphous series of layer-type inclusion complexes

The title ternary complexes (1, X=Cl;2, X=Br;3, X=CN) have been prepared and characterized by X-ray crystallography. Crystal data: space groupP2₁/n,Z=4;1,a=7.505(2),b=14.556(4),c=14.453(3) Å, =98.13(2)^o, andR _F=0.088 for 1831 observed MoK data;2,a=7.483(1),b=14.643(6),c=14.443 Å, =98.25(2)^o, andR _F=0.113 for 923 data;3,a=7.490(2),b=14.646(5),c=14.594(5) Å, =98.85(5)^o, andR _F=0.082 for 915 data. In the isomorphous crystal structure of1 and2, ordered (C₂H₅)₄N⁺ cations are sandwiched between puckered layers matching the (020) family of planes, each being constructed from the cross-linking of planar zigzag chains of hydrogen-bonded urea molecules by the water molecules and halide ions. Compound3 has the same structure except that its cyanide group is disordered. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82066 (30 pages).Operated under contract DE-AC02-76CH00016 with the U.S. Department of Energy, Office of Basic Energy Science.