Electronic structure of bis(o-iminobenzosemiquinonato)metal complexes (Cu, Ni, Pd).: The art of establishing physical oxidation states in transition-metal complexes containing radical ligands
Electronic structure of bis(o-iminobenzosemiquinonato)metal complexes (Cu, Ni, Pd).: The art of establishing physical oxidation states in transition-metal complexes containing radical ligands
复制标题
DOI：
10.1021/ja003831d
复制
发表时间：
2001-03-14
影响因子：
15
通讯作者：
Wieghardt, K
中科院分区：
文献类型：
--
作者：
Chaudhuri, P;Verani, CN;Wieghardt, K
配体2-苯胺基-4，6-二叔丁基苯酚及其类似物2-（3，5-二氯苯胺基）-4，6-二叔丁基苯酚在空气和三乙胺存在下，在乙腈或甲醇溶液中与二价过渡金属离子反应。根据金属：配体比率（1：1、1：2或1：3）和环胺1，4-二甲基-1，4，7-三氮杂环壬烷（dmtacn）的存在（或不存在），分离出以下作为结晶固体的络合物：[Co-III（L-ISQ）（3）]（1）; [Cu-II（dmtacn）（L-ISQ）] PF 6（2）; [Cu-II（L-ISQ）（2）]（3）; [Ni-II（L-ISQ）（2）]（4a）; [Ni-II（L-Cl（ISQ））（2）]（4 b）; [Pd-II（L-ISQ）（2）]（5）。（L-ISQ）（-）表示单阴离子邻亚氨基苯并半醌自由基（S-rad = 1/2）。化合物1-5在100（2）K下通过单晶X射线晶体学表征。对于所有的配合物，它是明确确立的O，N-协调的o-亚氨基benzosemiquinonato（1-）配体存在。配合物3，4 b和5是正方形平面分子，分别具有S-t = 1/2，0和0基态，如通过H-1 NMR和EPR光谱和变温磁化率测量所建立的。配合物2具有S-t = 1的基态，其通过Cu-II离子的d（x ~ 2-y ~ 2）磁轨道与配体自由基的π轨道之间的强分子内铁磁耦合（J = +195 cm ~（-1））获得。复合体1包含三个相互正交的（L-ISQ）（-.）配体，并具有S-t = 3/2基态。计算结果表明，化合物4a和5的电子结构可以用单重态双自由基来描述，其中含有一个二价的反磁性d（8）构型的中心金属离子和两个强反铁磁耦合（L-ISQ）（-）自由基配体.它的结论是，在经典的双（邻-diiminobenzosemiquinonato）-和双（邻-benzosemiquinonato）金属配合物的镍-II，钯-II，和铂-II的电子结构普遍存在。所有配合物的电化学进行了详细的研究。对于3、1a和5，一系列可逆的单电子转移波导致阴离子和阳离子[M（L）（2）]（2-，1-，1+，2+）的形成，其已被光谱电化学表征。所有的氧化还原过程被证明是基于配体的。
The ligand 2-anilino-4,6-di-tert-butylphenol and its 2-(3,5-dichloroanilino)-4,6-di-tert-butylphenol analogue react in CH3CN or CH3OH solutions with divalent transition metal ions in the presence of air and triethylamine. Depending on the metal:ligand ratio (1:1, 1:2, or 1:3) and the presence (or absence) of the cyclic amine 1,4-dimethyl-1,4,7-triazacyclononane (dmtacn), the following complexes have been isolated as crystalline solids: [Co-III(L-ISQ)(3)] (1); [Cu-II(dmtacn)(L-ISQ)]PF6 (2); [Cu-II(L-ISQ)(2)] (3); [Ni-II(L-ISQ)(2)] (4a); [Ni-II(L-Cl(ISQ))(2)] (4b); [Pd-II(L-ISQ)(2)] (5). (L-ISQ)(-) represents the monoanionic o-iminobenzosemiquinonate radical (S-rad = 1/2). Compounds 1-5 have been characterized by single-crystal X-ray crystallography at 100(2) K. For all complexes it is unambiguously established that the O,N-coordinated o-iminobenzosemiquinonato(1-) ligand is present. Complexes 3, 4b, and 5 are square planar molecules which possess an S-t = 1/2, 0, and 0 ground state, respectively, as was established by H-1 NMR and EPR spectroscopies and variable-temperature magnetic susceptibility measurements. Complex 2 possesses an S-t = 1 ground state which is attained via strong intramolecular ferromagnetic coupling (J = +195 cm(-1)) between the d(x2-y2) magnetic orbital of the Cu-II ion and the pi -orbital of the ligand radical. Complex 1 contains three mutually orthogonal (L-ISQ)(-.) ligands and has an S-t = 3/2 ground state. It is shown that the electronic structure of 4a and 5 is adequately described as singlet diradical containing a divalent, diamagnetic d(8) configurated central metal ion and two strongly antiferromagnetically coupled (L-ISQ)(-) radical ligands. It is concluded that the same electronic structure prevails in the classic bis(o-diiminobenzosemiquinonato)- and bis(o-benzosemiquinonato)metal complexes of Ni-II, Pd-II, and Pt-II. The electrochemistry of all complexes has been investigated in detail. For 3, la, and 5 a series of reversible one-electron-transfer waves leads to the formation of the anions and cations [M(L)(2)](2-,1-,1+,2+) which have been characterized spectroelectrochemically. All redox processes are shown to be ligand-based.