Maity Suvendu, Kundu Suman, Weyhermüller Thomas, Ghosh Prasanta
Department of Chemistry, R. K. Mission Residential College , Narendrapur, Kolkata-103, India.
Inorg Chem. 2015 Feb 16;54(4):1300-13. doi: 10.1021/ic502750u. Epub 2015 Feb 4.
Tris(abpy) complexes of types mer-[Cu(II)(abpy)3][PF6]2 (mer-1(2+)[PF6(–)]2) and ctc-[Cu(II)(abpy)2(bpy)][PF6]2 (ctc-2(2+)[PF6(–)]2) were successfully isolated and characterized by spectra and single-crystal X-ray structure determinations (abpy = 2,2′-azobispyridine; bpy = 2,2′-bipyridine). Reactions of mer-1(2+) and ctc-2(2+) ions with catechol, o-aminophenol, p-phenylenediamine, and diphenylamine (Ph–NH–Ph) in 2:1 molar ratio afford CuI(abpy)2 (3(+)) and corresponding quinone derivatives. The similar reactions of Cu(II)(bpy)3 and Cu(II)(phen)3 with these substrates yielding Cu(I)(bpy)2 and Cu(I)(phen)2 imply that these complexes undergo reduction-induced ligand dissociation reactions (phen = 1,10-phenanthroline). The average −N═N– lengths in mer-1(2+)[PF6(–)]2 and ctc-2(2+)[PF6(–)]2 are 1.248(4), while that in 3(+)[PF6(–)]·2CH2Cl2 is relatively longer, 1.275(2) Å, due to dCu → πazo* back bonding. In cyclic voltammetry, mer-1(2+) exhibits one quasi-reversible wave at −0.42 V due to Cu(II)/Cu(I) and abpy/abpy(•–) couples and two reversible waves at −0.90 and −1.28 V due to abpy/abpy(•–) couple, while those of ctc-2(2+) ion appear at −0.44, −0.86, and −1.10 V versus Fc(+)/Fc couple. The anodic 3(2+)/3(+) and the cathodic 3(+)/3 redox waves at +0.33 and −0.40 V are reversible. The electron paramagnetic resonance spectra and density functional theory (DFT) calculations authenticated the existence of abpy anion radical (abpy(•–)) in 3, which is defined as a hybrid state of [Cu(I)(abpy(0.5•–))(abpy(0.5•–))] and [Cu(II)(abpy(•–))(abpy(•–))] states. 3(2+) ion is a neutral abpy complex of copper(II) of type Cu(II)(abpy)2. 3 exhibits a near-IR absorption band at 2400–3000 nm because of the intervalence ligand-to-ligand charge transfer, elucidated by time-dependent DFT calculations in CH2Cl2.
成功分离出了顺式-[Cu(II)(abpy)₃][PF₆]₂（顺式-1(2 +)[PF₆(–)]₂）和反式-[Cu(II)(abpy)₂(bpy)][PF₆]₂（反式-2(2 +)[PF₆(–)]₂）类型的三（abpy）配合物，并通过光谱和单晶X射线结构测定对其进行了表征（abpy = 2,2′-偶氮双吡啶；bpy = 2,2′-联吡啶）。顺式-1(2 +)和反式-2(2 +)离子与邻苯二酚、邻氨基酚、对苯二胺和二苯胺（Ph–NH–Ph）以2:1的摩尔比反应，生成CuI(abpy)₂（3(+)）和相应的醌衍生物。[Cu(II)(bpy)₃](2 +)和[Cu(II)(phen)₃](2 +)与这些底物的类似反应生成Cu(I)(bpy)₂和Cu(I)(phen)₂，这表明这些配合物会发生还原诱导的配体解离反应（phen = 1,10-菲咯啉）。顺式-1(2 +)[PF₆(–)]₂和反式-2(2 +)[PF₆(–)]₂中的平均−N═N–长度为1.248(4)，而在3(+)[PF₆(–)]·2CH₂Cl₂中由于dCu→πazo*反馈键合，该长度相对较长，为1.275(2) Å。在循环伏安法中，顺式-1(2 +)由于Cu(II)/Cu(I)和abpy/abpy(•–)电对在−0.42 V处表现出一个准可逆波，由于abpy/abpy(•–)电对在−0.90和−1.28 V处表现出两个可逆波，而反式-2(2 +)离子的波相对于Fc(+)/Fc电对出现在−0.44、−0.86和−1.10 V处。在+0.33和−0.40 V处的阳极3(2 +)/3(+)和阴极3(+)/3氧化还原波是可逆的。电子顺磁共振光谱和密度泛函理论（DFT）计算证实了3中abpy阴离子自由基（abpy(•–)）的存在，其被定义为[Cu(I)(abpy(0.5•–))(abpy(0.5•–))]和[Cu(II)(abpy(•–))(abpy(•–))]状态的混合态。3(2 +)离子是[Cu(II)(abpy)₂](2 +)类型的中性铜(II) abpy配合物。由于价间配体到配体的电荷转移，3在2400 - 3000 nm处表现出近红外吸收带，这在CH₂Cl₂中通过含时DFT计算得到了阐明。
