Three-Coordinate Copper(I) Amido and Aminyl Radical Complexes
Three-Coordinate Copper(I) Amido and Aminyl Radical Complexes
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DOI：
10.1021/ja809834k
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发表时间：
2009-03-25
影响因子：
15
通讯作者：
Peters, Jonas C.
中科院分区：
文献类型：
--
作者：
Mankad, Neal P.;Antholine, William E.;Peters, Jonas C.
分离和表征了阴离子双膦硼酸盐配体[Ph2B((CH2PBu2)-Bu-t)(2)](-)负载的三配位铜-NR2体系(R=对甲苯基)的阴离子Cu-I和中性(正式)Cu-II氧化态。一个较大的自交换电子转移反应速率常数(k(S)>；=10(7)M~(-1)S~(-1))使该体系成为蓝铜蛋白中第一类活性中心的函数模型。多边X射线吸收光谱、多频电子顺磁共振和密度泛函理论分析表明，氧化形式最好是铜-I-氨基自由基络合物，而不是铜-II-氨基物种，其中约70%的未成对电子定位在NR2单元上。氢原子转移和C-C偶联反应是这种不寻常的电子结构所表现出的化学反应的例子。
A three-coordinate Cu-NR2 system (R = p-tolyl) supported by the anionic bis(phosphino)borate ligand [Ph2B((CH2PBu2)-Bu-t)(2)](-) has been isolated and structurally characterized in both its anionic Cu-I and neutral (formally) Cu-II oxidation states. A large rate constant for the self-exchange electron - transfer reaction (k(s) >= 10(7) M-1 s(-1)) makes this system a functional model for the type-1 active sites in blue copper proteins. Multiedge X-ray absorption spectroscopy, multifrequency electron paramagnetic resonance, and density functional theory analyses collectively indicate that the oxidized form is best regarded as a Cu-I-aminyl radical complex rather than a Cu-II-amido species, with about 70% localization of the unpaired electron on the NR2 unit. Hydrogen-atom transfer and C-C coupling reactions are presented as examples of chemical reactivity manifested by this unusual electronic structure.