CRYSTAL AND MOLECULAR-STRUCTURE OF THE HOST-GUEST (2 1)COMPLEX OF TRIFLUOROMONOAQUABORON(III) WITH THE CIS-ANTI-CIS-ISOMER OF DICYCLOHEXANO-18-CROWN-6/

Reaction of BF3.(C2H5)(2)O with the cis-anti-cis-isomer of dicyclohexa no-18-crown-6 (DCH-6B) in the presence of atmospheric moisture yields [(BF3.H2O)(2). (DCH-6B)]. The structure of this complex is determined by X-ray diffraction analysis. The data of H-1 NMR and ER spectroscopy and thermogravimetry agree with the structural data. The crystals are monoclinic, sp. gr. P2(1)/n, a = 8.686(3), b = 18.802(8), and c = 8.2 09(3) Angstrom, beta = 81.59(2)degrees, Z = 2, and the final R-factor is 0.082. The perchlike structure is built of the molecules BF3.H2O an d DCH-6B (2:1), which are linked together into the molecular complex b y an OH ... O hydrogen-bonded network. Four oxygen atoms of the crown ether are involved in hydrogen bonding as proton accepters (O-H2O... O -cr are 2.589-2.632 Angstrom). The O-(H2O) oxygen atom deviates from t he plane defined by six oxygen atoms of the macrocycle by 1.406 Angstr om. In the complex, the crown-ether molecule adopts the Ci symmetry.