Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring55, D-70550 Stuttgart, Germany.
Dalton Trans. 2013 Dec 7;42(45):16142-50. doi: 10.1039/c3dt51360b. Epub 2013 Sep 10.
1,2,4,5-Tetracyanobenzene (TCNB) was reacted with Cu(dppf)(CH3CN)2 and Cu(dchpf)(CH3CN), dppf = 1,1'-bis(diphenylphosphino)ferrocene and dchpf = 1,1'-bis(dicyclohexylphosphino)ferrocene, to produce a heterotetranuclear metallamacrocycle 1, {Cu(dppf)(μ-TCNB)}2, and a heterooctanuclear complex 2, {Cu(dchpf)}4(μ4-TCNB)4. Complex 1 is the first example of a structurally characterised discrete transition metal complex of TCNB. Upon crystallisation attempts, compound 2 formed the structurally identified coordination polymer 3, {[Cu(dchpf)(μ-TCNB)]2(BF4)2}n. Structural and spectroscopic analyses confirmed the redox-innocent behaviour of TCNB in 1, 2 and 3. However, the soluble compounds 1 and 2 could be oxidised and reduced spectroelectrochemically (UV-vis, IR, and EPR). The oxidation occurs invariably at the ferrocene sites without notable splitting of redox potentials. Reduction involves the TCNB bridging ligands to produce radical complexes. As a variably bridging acceptor component of supramolecular structures the TCNB ligand thus adopts an intermediate position between the highly electron transfer-active TCNE, TCNQ and TCNQF4 systems and the numerous redox-innocent bridges.
1,2,4,5-四氰基苯（TCNB）与[Cu（dppf）（CH3CN）2]（BF4）和[Cu（dchpf）（CH3CN）]（BF4）反应，dppf=1,1'-双（二苯基膦）二茂铁，dchpf=1,1'-双（二环己基膦）二茂铁，生成了一个杂四核金属大环配合物 1，{[Cu（dppf）（μ-TCNB）]（BF4）}2，和一个杂八核配合物 2，[{Cu（dchpf）}4（μ4-TCNB）]（BF4）4。配合物 1 是 TCNB 的第一个结构特征明确的离散过渡金属配合物的例子。在结晶尝试中，化合物 2 形成了结构确定的配位聚合物 3，{[Cu（dchpf）（μ-TCNB）]2（BF4）2}n。结构和光谱分析证实了 TCNB 在 1、2 和 3 中的氧化还原惰性行为。然而，可溶性化合物 1 和 2 可以通过光谱电化学（紫外-可见、红外和电子顺磁共振）进行氧化和还原。氧化总是在二茂铁部位发生，而氧化还原电位没有明显分裂。还原涉及 TCNB 桥连配体，生成自由基配合物。作为超分子结构中可变桥接受体成分，TCNB 配体在高度电子转移活性的 TCNE、TCNQ 和 TCNQF4 体系与众多氧化还原惰性桥之间处于中间位置。
