Coordination chemistry of anticrowns. Complexation of cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 with the cyanoborohydride anion [H3BCN]− and triethylamineborane Et3NBH3

As was shown by IR spectroscopy, the reaction of the three-mercury anticrown (o-C6F4Hg)3 (1) with the [H3BCN]ion in THF affords the complexes {[(o-C6F4Hg)3][H3BCN](5) and [(o-C6F4Hg)3]2[H3BCN](6). Complex 6 was isolated from solution in the analytically pure state. According to X-ray diffraction data, complex 6 has a double-decker sandwich structure, in which the borohydride group of the [H3BCN]− anion is bound to one anticrown molecule by three B-H-Hg bridges, whereas the cyanide group is cooperatively coordinated by three mercury centers of another molecule 1 through the nitrogen atom. The reaction of compound 1 with triethylamineborane Et3NBH3 in THF affords the 1: 1 complex ∼[(o-C6F4Hg)3][Et3NBH3]∼ (7). In this adduct, the binding of the aminoborane to the mercury anticrown is also accomplished by B-H-Hg bridges. The stability constants of complexes 5 and 6 in THF were determined.