He Jiang, Rauch Florian, Krummenacher Ivo, Braunschweig Holger, Finze Maik, Marder Todd B
Institute for Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Dalton Trans. 2021 Jan 7;50(1):355-361. doi: 10.1039/d0dt03619f. Epub 2020 Dec 15.
Two derivatives of phenylpyridyl-fused boroles were prepared via functionalization of the pyridyl groups, namely to an electron-rich dihydropyridine moiety (compound 1) and an electron-deficient N-methylpyridinium cation (compound 2). Due to strong conjugation between the dihydropyridine moiety and the boron atom, the reduction potential of compound 1 shifts cathodically. In contrast, compound 2 exhibits three reduction processes with a first reversible reduction potential anodically shifted in comparison to its precursor (TipPBB2) or the non-borylated framework 1-methyl-2-phenylpyridin-1-ium triflate (3). The significantly anodically shifted reduction potential indicates the extreme electron deficiency of compound 2, which also leads to the reversible coordination of THF. Photophysical properties of both compounds in different solvents were investigated. Theoretical studies further support the strong conjugation in the ground state of compound 1 and the electron-deficient property of compound 2.
通过吡啶基团的官能化制备了两种苯基吡啶稠合硼咯衍生物，即富电子的二氢吡啶部分（化合物1）和缺电子的N-甲基吡啶鎓阳离子（化合物2）。由于二氢吡啶部分与硼原子之间存在强共轭作用，化合物1的还原电位向阴极移动。相比之下，化合物2表现出三个还原过程，其第一个可逆还原电位与其前体（TipPBB2）或非硼化骨架三氟甲磺酸1-甲基-2-苯基吡啶鎓（3）相比向阳极移动。显著向阳极移动的还原电位表明化合物2具有极端的电子缺乏性，这也导致了四氢呋喃的可逆配位。研究了两种化合物在不同溶剂中的光物理性质。理论研究进一步支持了化合物1基态中的强共轭作用以及化合物2的缺电子性质。
