Department of Chemistry, University College of Science, University of Calcutta, 92 APC Road, Kolkata 700009, India.
Dalton Trans. 2021 Apr 7;50(13):4686-4699. doi: 10.1039/d0dt04337k. Epub 2021 Mar 17.
A new Ni(ii) complex [NiL] (complex 1) of an asymmetrically di-condensed NO donor Schiff base ligand, N-salicylidene-N'-3-methoxysalicylidene-1,3-propanediamine (HL), has been synthesized and utilized for the synthesis of three heterometallic complexes, [(NiL)Mn(NCS)(CHOH)]·CHOH (2) [(NiL)Mn(N(CN))(CHOH)]·CHOH (3) and [(NiL)Mn(N)(μ-N)(CHOH)] (4). Single crystal X-ray diffraction analyses show that complexes 2 and 3 have linear trinuclear structures where two tridentate O donor (NiL) units are coordinated to the central octahedral Mn(ii) centre, whereas complex 4 has a centrosymmetric tetranuclear structure where two binuclear (NiL)Mn units are linked via two phenoxido and two μ-N bridges. Among the heterometallic complexes (2-4), only 4 is active towards the catalytic oxidation of 3,5-di-tert-butylcatechol to the corresponding quinone. The turnover number for the aerobic oxidation of 3,5-DTBC is 935 h. ESI-mass spectra have been recorded to scrutinize the mechanistic pathway of this catalytic reaction. Variable temperature magnetic susceptibility measurements suggest that complexes 2-4 are antiferromagnetically coupled with coupling constants (J) of -4.84 and -5.23 cm for complexes 2 and 3, respectively and J = -2.20 cm, J = 1.13 cm and J = -1.12 cm for complex 4. DFT calculations have been used to rationalize the magnetic super-exchange in complexes 2-4, by computing the theoretical coupling constants and analyzing the spin density plots.
一种新的 Ni(ii) 配合物[NiL]（配合物 1），由不对称双缩合的 NO 供体希夫碱配体 N-水杨醛基-N'-3-甲氧基水杨醛基-1,3-丙二胺（HL）合成，并用于合成三种杂金属配合物，[(NiL)Mn(NCS)(CHOH)]·CHOH（2）[(NiL)Mn(N(CN))(CHOH)]·CHOH（3）和[(NiL)Mn(N)(μ-N)(CHOH)]（4）。单晶 X 射线衍射分析表明，配合物 2 和 3 具有线性三核结构，其中两个三齿 O 供体（NiL）单元与中心八面体 Mn(ii)中心配位，而配合物 4 具有对称的四核结构，其中两个双核（NiL）Mn 单元通过两个苯氧和两个μ-N 桥连接。在杂金属配合物（2-4）中，只有 4 对 3,5-二叔丁基儿茶酚的催化氧化有活性，生成相应的醌。3,5-DTBC 有氧氧化的转化率数为 935 h。记录了 ESI-质谱以仔细研究该催化反应的机理途径。变温磁化率测量表明，配合物 2-4 呈反铁磁耦合，耦合常数（J）分别为-4.84 和-5.23 cm ，配合物 4 的 J = -2.20 cm，J = 1.13 cm 和 J = -1.12 cm。DFT 计算用于通过计算理论耦合常数和分析自旋密度图来合理化配合物 2-4 中的磁超交换。
