Department of Chemistry and Biochemistry, The University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada.
Department of Chemistry and Biochemistry, The Florida State University, 102 Varsity Way, Tallahassee, FL, 32306-4390, USA.
Chemistry. 2020 Sep 1;26(49):11180-11186. doi: 10.1002/chem.202001218. Epub 2020 Aug 6.
Herein, we establish the preparation, characterization, and reactivity of a new diphosphine ligand, 1,2-bis(di(3-dicyclohexylboraneyl)propylphosphino)ethane (P B ), a scaffold that contains four pendant boranes. An entryway into the coordination chemistry of P B is established by using nickel, providing the octaboraneyl complex [Ni(P B ) ]-this species contains a boron-rich secondary coordination sphere that reacts readily with Lewis bases. In the case of 4,4'-bipyridine, an air-sensitive coordination polymer is obtained. Characterization of this material by solid-state NMR and EPR spectroscopy reveals the presence of a charge-transfer polymer, which forms as a function of intramolecular Ni→4,4'-bpy electron transfer (ET), providing an array of oxidized nickel sites and reduced 4,4'-bpy radical anion sites. Notably, the related intermolecular reaction between the model fragments [Ni(dnppe) ] (dnppe=1,2-bis(di-n-propylphosphino)ethane) and a bis(boraneyl)-protected 4,4'-bpy, provides no ET. Overall, the P B fragment provides a unique opportunity for Lewis base activation, in one case allowing for the facile construction of monomers for incorporation into redox-active macromolecules.
在此，我们建立了一种新的双膦配体 1,2-双（二（3-二环己基硼基）丙基膦基）乙烷（P B ）的制备、表征和反应性，该配体含有四个悬垂硼烷。通过使用镍，为 P B 的配位化学建立了一个入口，提供了八硼烷基配合物[Ni(P B )]-该物种含有丰富的硼的次级配位球，容易与路易斯碱反应。在 4,4'-联吡啶的情况下，得到了一种对空气敏感的配位聚合物。通过固态 NMR 和 EPR 光谱对该材料的表征表明，存在电荷转移聚合物，其作为分子内 Ni→4,4'-bpy 电子转移（ET）的函数形成，提供了一系列氧化镍位点和还原 4,4'-bpy 自由基阴离子位点。值得注意的是，模型片段[Ni(dnppe)]（dnppe=1,2-双（二-n-丙基膦基）乙烷）和双（硼烷基）保护的 4,4'-bpy 之间的相关分子间反应没有 ET。总体而言，P B 片段为路易斯碱的活化提供了一个独特的机会，在一种情况下，它允许容易地构建单体以纳入氧化还原活性大分子。
