Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata-103, India.
Inorg Chem. 2013 Jul 1;52(13):7417-30. doi: 10.1021/ic400166z. Epub 2013 Jun 20.
A new family of oxidovanadium complexes, [(L1(R))(VO)(L(R(')))] (R = H, R' = H, 1; R = H, R' = -CMe3, 2; R = H, R' = Me, 3; R = -CMe3, R' = H, 4 and R = -CMe3, R' = -CMe3, 5), incorporating tridentate L1(R)H ligands (L1(R)H = 2,4-di-R-6-{(2-(pyridin-2-yl)hydrazono)methyl}phenol) and substituted catechols (L(R('))H2) was substantiated. The V-Ophenolato (cis to V═O), V-OCAT (cis to V═O) and V-OCAT (trans to V═O) lengths span the ranges, 1.894(2)-1.910(2), 1.868(2)-1.887(2), and 2.120(2)-2.180(2) Å. The metrical oxidation states (MOS) of the catechols in 1-5 are fractional and vary from -1.43 to -1.60. The (51)V isotropic chemical shifts of solids and solutions of 1-5 are deshielded ((51)V CP MAS: -19.8 to +248.6; DMSO-d6: +173.9 to +414.55 ppm). The closed shell singlet (CSS) solutions of 1-5 are unstable due to open shell singlet (OSS) perturbations. The ground electronic states of 1-5 are defined by the resonance contribution of the catecholates (L(R('))CAT(2-)) and L(R('))SQ(-•) coordinated to the VO and VO ions. 1-5 are reversibly reducible by one electron at -(0.58-0.87) V, referenced vs ferrocenium/ferrocene, to VO(2+) complexes, (L1(R-))(VO(2+))(L(R('))CAT(2-)) 1-5. 1-5 display another quasi-reversible or irreversible reduction wave at -(0.80-1.32) V due to the formation of hydrazone anion radical (L1(R2-•)) complexes, (L1(R2-•))(VO(2+))(L(R('))CAT(2-)), 1-5, with S = 1 authenticated by the unrestricted density functional theory (DFT) calculations on 1(2-) and 3(2-) ions. Frozen glasses electron paramagnetic resonance (EPR) spectra of 1-5 ions [e.g., for 2, g|| = 1.948, g⊥ = 1.979, A|| = 164, A⊥ = 60] affirmed that 1-5 ions are the VO complexes of L(R')CAT(2-). Spectro-electrochemical measurements and time-dependent DFT (TD DFT) calculations on 1, 3, 1(-), 3(-), and 1(2-) disclosed that the near infrared (NIR) absorption bands of 1-5 at 800 nm are due to the CSS-OSS metal to ligand charge transfer which are red-shifted in the solid state and disappear in 1-5 and 1-5 ions.
一种新的氧化钒配合物家族，[(L1(R))(VO)(L(R(')))]（R = H，R' = H，1；R = H，R' = -CMe3，2；R = H，R' = Me，3；R = -CMe3，R' = H，4 和 R = -CMe3，R' = -CMe3，5），包含三齿 L1(R)H 配体（L1(R)H = 2,4-二-R-6-{(2-(吡啶-2-基)腙基)甲基}苯酚）和取代儿茶酚（L(R('))H2）。V-邻苯二酚（顺式 V═O）、V-OCAT（顺式 V═O）和 V-OCAT（反式 V═O）的长度范围分别为 1.894(2)-1.910(2)、1.868(2)-1.887(2) 和 2.120(2)-2.180(2) Å。1-5 中儿茶酚的测度氧化态（MOS）为分数，范围为-1.43 至-1.60。1-5 的固态和溶液的（51）V 各向同性化学位移被去屏蔽（（51）V CP MAS：-19.8 至 +248.6；DMSO-d6：+173.9 至 +414.55 ppm）。1-5 的闭壳单重态（CSS）溶液由于开壳单重态（OSS）的干扰而不稳定。1-5 的基态电子态由儿茶酸盐（L(R('))CAT(2-))和 L(R('))SQ(-•)与VO和VO离子的共振贡献定义。1-5 可在-(0.58-0.87) V 下通过一个电子可逆还原为 VO(2+)配合物，(L1(R-))(VO(2+))(L(R('))CAT(2-)) 1-5。1-5 在-(0.80-1.32) V 处由于形成腙阴离子自由基（L1(R2-•))配合物(L1(R2-•))(VO(2+))(L(R('))CAT(2-))，1-5，而显示出另一个准可逆或不可逆还原波，S = 1 通过对 1(2-)和 3(2-)离子的无约束密度泛函理论（DFT）计算得到验证。1-5离子的冻结玻璃电子顺磁共振（EPR）谱[例如，对于 2，g|| = 1.948，g⊥ = 1.979，A|| = 164，A⊥ = 60]证实1-5离子是 L(R')CAT(2-)的VO配合物。1、3、1(-)、3(-)和 1(2-)的光谱电化学测量和时间依赖的 DFT（TD DFT）计算表明，1-5 在 800nm 处的近红外（NIR）吸收带归因于 CSS-OSS 金属到配体电荷转移，其在固态中发生红移并在1-5和1-5离子中消失。
