作者:Arindam Sarkar、Sushanta K. Pal、Mikhail E. Itkis、Fook S. Tham、Robert C. Haddon
DOI:10.1039/c2jm16001c
日期:——
We report a synthetic scheme for the preparation of alkylthio, dithio-bridged and diseleno-bridged 9-hydroxyphenalenones and associated spiro-biphenalenyl boron neutral radicals. We show that the strategy of sulfur substitution at the active positions of the phenalenyl units reduces the electrochemical disproportionation potential (ΔE2−1 = E2½ − E1½, where E1½ and E2½ are the first and second reduction potentials of corresponding cations) of the alkylthio-radicals [3,7-SR-PLY(O,O)]2B, (R = Me, 9), (R = Et, 10) and (R = Pr, 11), but brings about a significant reduction of the ΔE2−1 value in the case of disulfide and diselenide substitution, [3,4-S,S-PLY(O,O)]2B (12) and [3,4-Se,Se-PLY(O,O)]2B (13). The crystal structures of 10 and 11 show that the radicals exist as one dimensional (1-D) π-chains of superimposed phenalenyl units, and the molecular units pack more efficiently than the oxygen-substituted analog [3,7-OMe-PLY(O,O)]2B (8). Magnetic susceptibility measurements indicate that in the solid state the radicals remain paramagnetic while there is spin–spin interaction between the molecules along the π-chains. Band structure calculations are in accordance with the magnetic measurement data and indicate the presence of interactions between the molecules. The room temperature electrical conductivities of both compounds are found to be σRT = 1.5 × 10−2 S cm−1.
我们报告了一种制备烷硫基、二硫基桥联和二硒基桥联的 9-羟基苯那烯酮以及相关的螺联苯那烯基硼中性基团的合成方案。我们表明,苯酚基单元活性位置的硫取代策略降低了烷硫基自由基的电化学歧化电位(ΔE2−1 = E2½ - E1½,其中E1½和E2½是相应阳离子的第一和第二还原电位) [3,7-SR-PLY(O,O)]2B、(R = Me, 9)、(R = Et, 10) 和 (R = Pr, 11),但会显着降低 ΔE2−在二硫化物和二硒化物取代的情况下为 1 值,[3,4-S,S-PLY(O,O)]2B (12) 和 [3,4-Se,Se-PLY(O,O)]2B ( 13)。 10和11的晶体结构表明,自由基以叠加的苯酚单元的一维(1-D)π链形式存在,并且分子单元比氧取代的类似物[3,7-OMe-PLY( O,O)]2B (8)。磁化率测量表明,在固态下,自由基保持顺磁性,同时沿着 π 链的分子之间存在自旋-自旋相互作用。能带结构计算与磁性测量数据一致,并表明分子之间存在相互作用。两种化合物的室温电导率为 σRT = 1.5 × 10−2 S cm−1。