Synthesis and study of the structure of g -substituted dibenzoylmethanate of boron difluoride

A diketonate complex of boron difluoride has been obtained, in which the β-carbon atoms have phenyl groups, and the central carbon atom (g) has a 2-bromothioethyl group. The complex has been characterized by the results of elemental analysis, IR, 1H NMR spectroscopy, and X-ray diffraction analysis (XRD). According to X-ray diffraction data, the appearance of a substituent at the g-carbon atom leads to the rotation of the phenyl groups, due to necessity to compensate for the repulsion between them and the sulfur atom of the gamma substituent. The result of this reversal is the disruption of conjugation between the electronic systems of the chelate ring and β-substituents, which makes it impossible for the β-phenyl groups to conjugate with the π-electron system of the chelate ring. As a result, the g-substituted boron difluoride dibenzoylmethanate does not exhibit luminescent properties of the unsubstituted complex. The boron chelate cycles are located in the crystal, forming linear chains: the cycles of one chain are coplanar to each other and are identically oriented in space: the C-O bonds of the molecules forming the chain are parallel to the chain line and are one-way directed. In this case, the equatorially located fluorine atoms (F(2)) are coordinated at the sulfur atoms of the neighboring molecule. All atoms of the B-F(2)…S-C(2) fragment lie in the same plane. The formation of such structures is due to the coordination of a negatively charged fluorine atom at the substituent atom bonded with the g-carbon, which is slightly positively charged. Information about the structure of the resulting complex (tables of atomic coordinates, bond lengths, and bond angles) was deposited at the Cambridge Crystallographic Data Center no. 2174579, deposit@ccdc.cam.ac.uk; http://www.ccdc.cam.ac.uk).