Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States.
Department of Chemistry, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, United States.
Inorg Chem. 2020 Apr 6;59(7):4729-4740. doi: 10.1021/acs.inorgchem.9b03790. Epub 2020 Mar 18.
A tridentate [PPP] ligand has been used to construct a series of dimeric cobalt complexes and explore cooperative multielectron redox processes that are both metal- and ligand-centered. Reduction of (PPP)CoCl () with excess magnesium affords the CoCo N-heterocyclic phosphido (NHP)-bridged symmetric dimer [(μ-PPP)Co] (). Two-electron oxidation of with FcPF generates an asymmetrically bridged dication [(μ-PPP)Co][PF] () in which the oxidation has occurred in a delocalized fashion throughout the CoP core. In contrast, [(μ-PPP)Co] (), which can be generated either by one-electron oxidation of with FcPF or comportionation of and , features an asymmetric geometry and localized mixed valence. Treatment of with the milder reductants CoCp and KBEtH does not lead to formation of , , or but instead generates dimeric species [(PPP)CoCl] () and [(PPP)CoH] (). Unlike -, where the phosphine side arms of the tridentate [PPP] ligand span the two Co centers, complex and are connected solely by NHP ligands that bridge the two (PPP)Co fragments.
一种三齿[PPP]配体被用来构建一系列二聚钴配合物，并探索协同的多电子氧化还原过程，这些过程既涉及金属中心也涉及配体中心。用过量的镁还原(PPP)CoCl()得到CoCo 氮杂环膦基（NHP）桥接对称二聚体(μ-PPP)Co。用 FcPF 对与氧化，生成不对称桥联二阳离子[(μ-PPP)Co]PF，其中氧化在整个 CoP 核中以离域的方式发生。相比之下，(μ-PPP)Co，它可以通过用 FcPF 氧化或与的配位来生成，具有不对称的几何形状和局部混合价态。用较温和的还原剂 CoCp 和 KBEtH 处理不会生成、或，但会生成二聚体(PPP)CoCl和(PPP)CoH。与不同的是，在三齿[PPP]配体的膦侧臂跨越两个 Co 中心，而配合物和仅通过桥接两个(PPP)Co 片段的 NHP 配体连接。
