Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata-103, India.
Dalton Trans. 2011 Jan 7;40(1):146-55. doi: 10.1039/c0dt00883d. Epub 2010 Nov 11.
Two bis(unsymmetrical diimine) complexes of (L(NO(2))(ϕ1))(L(NO(2))(ϕ2))M(II)Cl(2) family with M = Fe and Mn, are reported (L(NO(2))(ϕ) = (E)-3-nitro-N-(pyridine-2-ylmethylene)aniline; ϕ = dihedral angle between the diimine unit including pyridine ring and the phenyl ring planes). Pure tcc-(L(NO2)(33.6))(L(NO2)(79.3))Fe(II)Cl(2)·0.5H(2)O (1) and tcc-(L(NO2)(32.0))(L(NO2)(79.4))Mn(II)Cl(2)·0.5H(2)O (2) isomers have been successfully isolated in high yields and characterized by elemental analyses, variable temperature magnetic susceptibility measurements, IR, mass, UV-vis and Mössbauer spectra including the single-crystal X-ray structure determinations that identified strong intermolecular non-bonding interactions in lattice (tcc refers to trans-cis-cis positions with respect to pyridine N-imine N-Cl donors). Geometries optimizations of all possible tcc, ttt, ctc, ccc and cct isomers of iron at the B3LYP/DFT level in gas-phase have shown that the tcc-isomer incorporating two non-equivalent ligands as in (L(NO(2))(42))(L(NO(2))(61))Fe(II)Cl(2), 1 (g), is stabilized by 6-20 kJ mol(-1) compared to other isomers where two ligands are equivalent. The frozen methanol glasses of 1 and 2 are luminescent at 77 K (1: λ(ext) = 370, λ(em) = 521 nm, χ(2) = 1.3, τ(avg) = 0.57 ns; 2: λ(ext) = 368, λ(em) = 524 nm, χ(2) = 1.1, τ(avg) = 0.90 ns). The DFT calculations have identified four closely spaced localized π(*) orbitals comprising of two non-equivalent ligands as UPMOs. The features contrast the tcc-isomer of (L(ϕ))(2)Fe(II)Cl(2) (3), congener of 1 without -NO(2) substitution and non-emissive (bpy)(2)Fe(II)Cl(2) (4) where two ligands are equivalent. TD-DFT calculations have assigned intra-ligand (IL) and ligand to ligand charge transfer (LLCT) dominated excited states as the origin of luminescence of 1 and 2.
两种（不对称二亚胺）配合物（L（NO（2））（ϕ1））（L（NO（2））（ϕ2））M（II）Cl（2）家族与 M = Fe 和 Mn，报告（L（NO（2））（ϕ）=（E）-3-硝基-N-（吡啶-2-亚甲基）苯胺; ϕ = 二面角包括吡啶环和苯环平面的二亚胺单元）。纯 tcc-（L（NO2）（33.6））（L（NO2）（79.3））Fe（II）Cl（2）·0.5H（2）O（1）和 tcc-（L（NO2）（32.0））（L（NO2）（79.4））Mn（II）Cl（2）·0.5H（2）O（2）是成功分离高收率和元素分析，变温磁化率测量，IR，质量，紫外 - 可见和穆斯堡尔光谱包括单晶 X 射线结构测定，确定晶格中的强分子间非键相互作用（tcc 是指相对于吡啶 N-亚胺 N-Cl 供体的顺式-顺式-顺式位置）。在气相中，所有可能的 tcc，ttt，ctc，ccc 和 cct 异构体的铁的几何优化表明，包含两个非等价配体的 tcc-异构体，如（L（NO（2））（42））（L（NO（2））（61））Fe（II）Cl（2），1（g），通过 6-20 kJ mol（-1）稳定与两个配体等价的其他异构体。1 和 2 的冷冻甲醇玻璃在 77 K 下发光（1：λ（ext）= 370，λ（em）= 521nm，χ（2）= 1.3，τ（avg）= 0.57 ns; 2：λ（ext）= 368，λ（em）= 524nm，χ（2）= 1.1，τ（avg）= 0.90 ns）。DFT 计算确定了四个紧密间隔的局域化π（*）轨道，由两个非等价配体组成 UPMO。特征与（L（ϕ））（2）Fe（II）Cl（2）（3）的 tcc-异构体形成对比，没有 -NO（2）取代且非发光的（bpy）（2）Fe（II）Cl（2）（4），其中两个配体是等价的。TD-DFT 计算将内配体（IL）和配体到配体电荷转移（LLCT）为主的激发态分配为 1 和 2 的发光起源。
