Osako Takao, Ueno Yoshiki, Tachi Yoshimitsu, Itoh Shinobu
Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
Inorg Chem. 2003 Dec 1;42(24):8087-97. doi: 10.1021/ic034958h.
Ligand effects on the structures and redox reactivities of copper complexes have been examined using (2-pyridyl)alkylamine derivatives as the supporting ligands, where particular attention has been focused on the effects of the alkyl linker chain length connecting the tertiary amine nitrogen atom and the pyridine nucleus: N[bond]CH(2)[bond]Py (Pym) vs N[bond]CH(2)CH(2)[bond]Py (Pye). X-ray crystallographic analysis of the copper(I) complex of tridentate ligand (Phe)L(Pym2) [N,N-di(2-pyridylmethyl)-2-phenylethylamine] (complex 1) has demonstrated that it possesses a trigonal pyramidal geometry in which a d[bond]pi interaction with an eta(1)-binding mode exists between the metal ion and one of the ortho carbons of the phenyl ring of the ligand side arm (phenethyl). The result shows sharp contrast to the d[bond]pi interaction with an eta(2)-binding mode existing in the copper(I) complex of (Phe)L(Pye2) [N,N-di[2-(2-pyridyl)ethyl]-2-phenethylamine] (complex 2). Such a d-pi interaction has been shown to affect the stability of the copper(I) complex in CH(2)Cl(2). Oxygenation of copper(I) complex 1 supported by (Phe)L(Pym2) produces a bis(mu-oxo)dicopper(III) complex, also being in sharp contrast to the case of the copper(I) complex 2 with ligand (Phe)L(Pye2), which preferentially affords a (micro-eta(2):eta(2)-peroxo)dicopper(II) complex in the reaction with O(2). Such an effect of the alkyl linker chain length of the metal binding site has also been found to operate in the RSSR (disulfide)/2RS(-) (thiolate) redox system. Namely, ligand (S2,R)L(Pym1) (di[2-[(alkyl)(2-pyridinylmethyl)amino]ethyl] disulfide) with the methylene linker group (Pym) induced the reductive disulfide bond cleavage in the reaction with copper(I) ion to give a bis(micro-thiolato)dicopper(II) complex, while the ligand with the ethylene linker group (Pye), (S2,Bn)L(Pye1) (di[2-[(benzyl)(2-(2-pyridinyl)ethyl)amino]ethyl] disulfide), gave a disulfide-dicopper(I) complex. These ligand effects in the Cu(2)[bond]O(2) and Cu(2)[bond]S(2) systems have been discussed by taking into account the difference in electron-donor ability of the pyridine nucleus between the Pym and Pye ligand systems.
以（2 - 吡啶基）烷基胺衍生物作为辅助配体，研究了配体对铜配合物结构和氧化还原反应活性的影响，其中特别关注连接叔胺氮原子和吡啶环的烷基连接链长度的影响：N[键]CH(2)[键]Py（Pym）与N[键]CH(2)CH(2)[键]Py（Pye）。三齿配体（Phe）L（Pym2）[N，N - 二（2 - 吡啶基甲基）-2 - 苯乙胺]（配合物1）的铜（I）配合物的X射线晶体学分析表明，它具有三角锥几何构型，其中在金属离子与配体侧臂（苯乙基）苯环的一个邻位碳之间存在以η(1) - 配位模式的d[键]π相互作用。该结果与（Phe）L（Pye2）[N，N - 二[2 - （2 - 吡啶基）乙基]-2 - 苯乙胺]（配合物2）的铜（I）配合物中存在的以η(2) - 配位模式的d[键]π相互作用形成鲜明对比。已表明这种d - π相互作用会影响铜（I）配合物在CH(2)Cl(2)中的稳定性。由（Phe）L（Pym2）支撑的铜（I）配合物1的氧化产生双（μ - 氧）二铜（III）配合物，这也与配体为（Phe）L（Pye2）的铜（I）配合物2的情况形成鲜明对比，后者在与O(2)反应时优先生成（μ - η(2):η(2) - 过氧）二铜（II）配合物。还发现金属结合位点的烷基连接链长度的这种影响在RSSR（二硫化物）/2RS(-)（硫醇盐）氧化还原体系中也起作用。也就是说，具有亚甲基连接基团（Pym）的配体（S2，R）L（Pym1）（二[2 - [(烷基）（2 - 吡啶基甲基）氨基]乙基]二硫化物）在与铜（I）离子反应时诱导二硫键的还原断裂，生成双（μ - 硫醇根）二铜（II）配合物，而具有乙烯连接基团（Pye）的配体（S2，Bn）L（Pye1）（二[2 - [(苄基）（2 - （2 - 吡啶基）乙基）氨基]乙基]二硫化物）则生成二硫化物 - 二铜（I）配合物。已通过考虑Pym和Pye配体体系中吡啶环给电子能力的差异，对Cu(2)[键]O(2)和Cu(2)[键]S(2)体系中的这些配体效应进行了讨论。
