NOVEL HYDROGEN-BONDED HOST LATTICES IN INCLUSION COMPOUNDS OF UREA AND PERALKYLATED AMMONIUM PENTABORATE SALTS.Thomas C.W. MAK* and Qi LI Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong

As a sequel to our continuing research program in the rational design of new urea/thiourea-anion host lattices,^1,2 two novel inclusion compounds containing hydrogen-bonded host networks constructed from urea and nonplanar pentaborate anions, (n-C₃H₇)₄N⁺[B₅O6(OH)₄]^- *4CO(NH₂)₂^.H₂O (1) and (n-C₄H₉)₄N⁺ [B₅O₆(OH)₄]^-. 2CO(NH₂)₂-B(OH)₃ (2), have been prepared and characterized by X-ray crystallography.

Compound 1 has a channel-like host lattice built of urea molecules, pentaborate ions and water molecules in a molar ratio of 4:1:1, and the (n-C₃H₇)₄N⁺ cations (represented by large circles) are arranged in a zigzag column within each channel (Fig. 1). Compound 2 features a two-dimensional open host network in which two channel systems extend parallel to the [101] and [010] directions, such that the (n-C₄H₉)₄N⁺ cations are accommodated in a stacked column within each channel of the first type (Fig.2) and in a zigzag column within each channel of the second type (Fig.3).

1. Q. Li and T. C. W. Mak: J. Incl. Phnom., 1995, 20, 73.

2. T. C. W. Mak, W. H. Yip and Q. Li: J. Am. Chem. Soc., 1995, 117, 11995.