CRYSTAL AND MOLECULAR-STRUCTURE OF UNSUBSTITUTED AND P-METHOXY-SUBSTITUTED ACETYLBENZOYLMETHANATOBORON DIFLUORIDE

The crystal structures of two borines were solved by direct methods an d refined by full-matrix least squares procedure. ethyl-4-phenyl-1,3,2 -(2H)-2,2-difluorodioxaborine, C10H9BF2O2 (compound 1): orthorhombic, space group Pnma, a = 12.534(2) Angstrom, b = 7.109(2) Angstrom, c = 1 0.933(2) Angstrom, Z = 4 and d = 1.43 Mg m(-3), R = 0.039 (Rw = 0.036) for 88 parameters and 752 observations with I>3 sigma(I). yl)-6-methy l-1,3,2-(2H)-2,2,2-difluorodioxaborine, C11H11BF2O3 (compound 2): mono clinic, space group P2(1)/m, a = 6.8889(8) Angstrom, b = 7.071(1) Angs trom, c = 11.695(2) Angstrom, beta = 98.55(1)degrees, V = 563.3(9) Ang strom(3), Z = 2 and d = 1.42 Mg m(-3), R = 0.039 (Rw = 0.036) for 100 parameters and 1003 observations with I>3 sigma(I). The crystal struct ure analysis of compound 1 and 2 reveals that the difference in their absorption and fluorescence spectra, by going from solution to the sol id state, reflects their packing in the crystal lattice which enables a charge transfer process to be developed between two planar molecules at ca. 3.5 Angstrom from each other in two different but parallel pla nes.