Structural studies of organoboron compounds. XLVI.1 5,5-Pentamethylene-2-phenyl-4,5-dihydrooxazol-N-oxide(NOB)trifluoroborane

The reaction of N-hydroxy-N-[(1-hydroxycyclohexyl)methyl]benzamide with dimethylether-boron trifluoride gives 5,5-penta-methylene-2-phenyl-4,5-dihydrooxazol-N-oxide(N—O—B)trifluoroborane [3-(2,2,2-trifluoro-1-oxa-2-borataethyl)-5,5- pentamethylence-2-phenyl-1-oxa-3-azonia-2-cyclopentene] in high yield. Crystals of the product are monoclinic, a = 8.1147(4), b = 15.448(1), c = 11.4144(6) A, β = 95.133(5)°, Z = 4, space group P21/c. the structure was solved by direct mothods and was refined by full-matrix least-squares procedures to R = 0.043 and Rw = 0.058 for 2178 reflections with I ≥ 3σ(I). the structure analysis confirms that the title compound has an open-chain boron-nitrogen betaine structure and, as such, is the first isolated and fully characterized open-chain non-chelate boron complex of a cycloimidate N-oxide (cyclohydroximate). Bond lengths (corrected for libration) involving the tetrahedrally coordinated boron atom are O—B = 1.530(3) and F—B = 1.370(2)–1.391(2) A.Key words: crystal structure, org...