Copper and Silver Complexes of a Redox-Active Diphosphine-Diboraanthracene Ligand
Copper and Silver Complexes of a Redox-Active Diphosphine-Diboraanthracene Ligand
复制标题
氧化还原活性二膦-二硼蒽配体的铜和银配合物
DOI：
10.1021/acs.inorgchem.8b02710
复制
发表时间：
2018
影响因子：
4.6
通讯作者：
Harman, W. Hill
中科院分区：
文献类型：
--
作者：
Taylor, Jordan W.;McSkimming, Alex;Moret, Marc-Etienne;Harman, W. Hill
氧化还原活性配体和Z型受体配体已经成为促进过渡金属中心多电子氧化还原化学的有前途的策略。在此，我们报告的铜和银配合物的二膦配体的特点是二硼蒽核心（B2 P2，9，10-双（2-（二异丙基膦基）苯基）-9，10-二氢硼蒽），这是能够作为一个氧化还原水库和Z-型配体的合成和表征。B_2P_2与CuX（X = Cl，Br，I）的金属化导致形成两种不同结构类型的式（B_2P_2）Cu_2X_2的双金属络合物，这取决于卤化物。Cu（I）阳离子[Cu（B2 P2）]+可以通过B2 P2与[Cu（CH 3CN）4][PF 6]的直接金属化或通过Na[BArF 4]（ArF= 3，5-双（三氟甲基）苯基）的卤化物提取并伴随CuX从Cu 2X2络合物中排出而获得。B2 P2与AgCl的金属化导致形成具有与氯硼酸根阴离子栓系的双膦Ag阳离子的两性Ag（B2 P2）Cl。非配位的[BArF 4]−的氯化物复分解得到阳离子[Ag（B2 P2）]+。阳离子[Cu（B2 P2）]+和[Ag（B2 P2）]+在相对于二茂铁/二茂铁氧化还原电对的1.6 V处表现出准可逆还原事件，并且由它们的还原产生的热敏自由基Cu（B2 P2）和Ag（B2 P2）通过EPR光谱表征，并且在后者的情况下，通过单晶X射线衍射表征。电子结构计算表明，这些中性自由基最好被描述为两性离子与还原中心的二硼蒽核心。
Redox-active ligands and Z-type acceptor ligands have emerged as promising strategies for promoting multielectron redox chemistry at transition-metal centers. Herein, we report the synthesis and characterization of copper and silver complexes of a diphosphine ligand featuring a diboraanthracene core (B2P2, 9,10-bis(2-(diisopropylphosphino)phenyl)-9,10-dihydroboranthrene) that is capable of serving as both a redox reservoir and a Z-type ligand. Metalation of B2P2with CuX (X = Cl, Br, I) results in the formation of bimetallic complexes of the formula (B2P2)Cu2X2of two different structure types, depending on the halide. The Cu(I) cation [Cu(B2P2)]+can be accessed by direct metalation of B2P2with [Cu(CH3CN)4][PF6] or by halide abstraction with Na[BArF4] (ArF= 3,5-bis(trifluoromethyl)phenyl) with concomitant expulsion of CuX from the bimetallic Cu2X2complexes. Metalation of B2P2with AgCl results in the formation of the zwitterion Ag(B2P2)Cl featuring a diphosphine Ag cation tethered to a chloroborate anion. Metathesis of chloride for the noncoordinating [BArF4]−affords the cation [Ag(B2P2)]+. The cations [Cu(B2P2)]+and [Ag(B2P2)]+exhibit quasireversible reduction events at ∼ −1.6 V versus the ferrocene/ferrocenium redox couple, and the thermally sensitive radicals that result from their reduction, Cu(B2P2) and Ag(B2P2), were characterized by EPR spectroscopy and, in the case of the latter, single-crystal X-ray diffraction. Electronic structure calculations suggest these neutral radicals are best described as zwitterions with reduction centered at the diboraanthracene core.