Wong Anthony, Chu Jiaxiang, Wu Guang, Telser Joshua, Dobrovetsky Roman, Ménard Gabriel
Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.
School of Chemical Science, University of Chinese Academy of Sciences, Huaibei hen, Huairou District, Beijing 101408, China.
Inorg Chem. 2020 Jul 20;59(14):10343-10352. doi: 10.1021/acs.inorgchem.0c01464. Epub 2020 Jul 9.
We report the synthesis of new Lewis-acidic boranes tethered to redox-active vanadium centers, (PhN)V(μ-N)B(CF) () and (N(CHCHN(CF)))V(μ-N)B(CF) (). Redox control of the V couple resulted in switchable borane versus "hidden" boron radical reactivity, mimicking frustrated Lewis versus frustrated radical pair (FLP/FRP) chemistry, respectively. Whereas heterolytic FLP-type addition reactions were observed with the V complex () in the presence of a bulky phosphine, homolytic peroxide, or Sn-hydride bond cleavage reactions were observed with the V complex, [CoCp][(N(CHCHN(CF)))V(μ-N)B(CF)] (), indicative of boron radical anion character. The extent of radical character was probed by spectroscopic and computational means. Together, these results demonstrate that control of the V oxidation states allows these compounds to access reactivity observed in both FLP and FRP chemistry.
我们报道了与氧化还原活性钒中心相连的新型路易斯酸性硼烷的合成，即(PhN)V(μ-N)B(CF)（）和(N(CHCHN(CF)))V(μ-N)B(CF)（）。钒偶的氧化还原控制分别导致了硼烷与“隐藏”硼自由基反应性的可切换，分别模拟了受阻路易斯对与受阻自由基对（FLP/FRP）化学。在存在大位阻膦的情况下，V配合物（）观察到异裂FLP型加成反应，而在V配合物[CoCp][(N(CHCHN(CF)))V(μ-N)B(CF)]（）中观察到均裂过氧化物或Sn-氢键裂解反应，这表明具有硼自由基阴离子特征。通过光谱和计算手段探究了自由基特征的程度。总之，这些结果表明，对钒氧化态的控制使这些化合物能够展现出在FLP和FRP化学中观察到的反应性。
