Department of Chemistry, University of Wisconsin-Madison , 1101 University Ave., Madison, Wisconsin 53706, United States.
Department of Chemistry, Emory University , 1515 Dickey Drive, Atlanta, Georgia 30322, United States.
J Am Chem Soc. 2016 Feb 17;138(6):1796-9. doi: 10.1021/jacs.5b12643. Epub 2016 Feb 2.
Bimetallic (Et4N)2[Co2(L)2], (Et4N)2[1] (where (L)(3-) = (N(o-PhNC(O)(i)Pr)2)(3-)) reacts with 2 equiv of O2 to form the monometallic species (Et4N)[Co(L)O2], (Et4N)[3]. A crystallographically characterized analog (Et4N)2[Co(L)CN], (Et4N)2[2], gives insight into the structure of 3. Magnetic measurements indicate 2 to be an unusual high-spin Co(II)-cyano species (S = 3/2), while IR, EXAFS, and EPR spectroscopies indicate 3 to be an end-on superoxide complex with an S = 1/2 ground state. By X-ray spectroscopy and calculations, 3 features a high-spin Co(II) center; the net S = 1/2 spin state arises after the Co electrons couple to both the O2(•-) and the aminyl radical on redox non-innocent (L(•))(2-). Dianion 1 shows both nucleophilic and electrophilic catalytic reactivity upon activation of O2 due to the presence of both a high-energy, filled O2(-) π* orbital and an empty low-lying O2(-) π* orbital in 3.
双金属（Et4N）2[Co2（L）2]，（Et4N）2[1]（其中（L）（3-）=（N（o-PhNC（O）（i）Pr）2）（3-））与 2 当量的 O2 反应形成单价物种（Et4N）[Co（L）O2]，（Et4N）[3]。一个结晶学表征的类似物（Et4N）2[Co（L）CN]，（Et4N）2[2]，深入了解[3]（1-）的结构。磁性测量表明[2]（2-）是一种不寻常的高自旋 Co（II）-氰基物种（S = 3/2），而 IR、EXAFS 和 EPR 光谱表明[3]（1-）是一个端到端的超氧化物络合物，具有 S = 1/2 的基态。通过 X 射线光谱和计算，[3]（1-）具有高自旋 Co（II）中心；在 Co 电子与 O2（•-）和氧化还原非中性（L（•））上的氨基自由基相互作用后，净 S = 1/2 自旋态出现。由于[3]（1-）中存在高能、充满的 O2（-）π轨道和空的低能 O2（-）π轨道，二阴离子[1]（2-）在 O2 激活后表现出亲核和亲电催化活性。
