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首页> 外文期刊>Bulletin of the Chemical Society of Japan >Syntheses and Redox Properties of Complexes with Mo3S4 Cores and Tridentate Schiff Base Ligands
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Syntheses and Redox Properties of Complexes with Mo3S4 Cores and Tridentate Schiff Base Ligands

机译：用MO3S4芯和三齿席夫碱配体合成和氧化还原性能

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A series of potentially tridentate Schiff base ligands, {HOPhC=N-(CH2)(3)-XMe: X = S (HLSMe), Se (HLSeMe)}, was prepared by condensation reactions of salicylaldehyde and the corresponding functionalized propylamines. These ligands were used to form the monocationic complexes, [Mo3S4(LXMe)(3)](+) (X = S (1(+)), Se (2(+))), through treatment of [Mo3S4(H2O)(9)](4+) with the appropriate Schiff base ligand in methanol. Single-crystal X-ray structural analysis of 1-PF6 revealed that one Schiff base ligand coordinates to each Mo via the O, N, and SMe donor atoms, and then the mono cationic cluster [Mo3S4(LSMe)(3)](+) has a pseudo C-3 symmetry if the chirality around the coordinated sulfur atoms is not taken into account. Because of the arrangements of the asymmetric Schiff base ligand, this monocationic cluster possibly adopts one of two axial chiralities. Furthermore, each sulfur atom of the three coordinated SMe groups in the complex cation is also chiral affording the two enantiomers observed in the unit cell. Dynamic behaviors of complexes 1-PF6 and 2-PF6 in solution were examined using line shape analyses of variable temperature NMR spectra revealing that the rate constant of the chiral inversion at the S atoms in 1-PF6 is greater than that at the Se atoms in 2-PF6 and the difference in the Delta H double dagger values of 1-PF6 (47.1 kJmol(-1)) and 2-PF6 (56.7 kJ mol(-1)) and the negative Delta S double dagger values (-39.9 and -57.5 Jmol(-1) K-1 for 1-PF6 and 2-PF6, respectively) suggest that the inversion processes involve bond cleavage between the metal centers and S or Se atoms followed by coordination of solvent molecules. The electrochemical properties of 1-PF6 and 2-PF6 were evaluated using cyclic voltammetry and this revealed that both 1(+) and 2(+) exhibit two consecutive, reversible one-electron reduction waves that are assigned to formal Mo(IV IV IV)/Mo(III IV IV) and Mo(111 IV IV)/ Mo(III III IV) couples, respectively. The ability of 1-PF6 and 2-PF6 to catalyze the electroreduction of H+ was also examined using CH3CO2H or CF3CO2H as a proton source. Noteworthy, the redox potentials for the catalytic wave depend on the acidity of the added acids. Thus, the catalytic current around the first reduction wave is observed in the presence of the stronger trifluoroacetic acid as a proton source, while the current around the second reduction wave appears when the weaker acetic acid is used.
机译：通过水杨醛和相应的官能化丙胺的缩合反应制备了一系列潜在的三齿席克碱配体，{Hophc = N-（CH2）（3）-XME：X = S（HLSME），SE（HLSEME）}。这些配体用于形成单子系列复合物，通过治疗[MO3S4（H2O），[MO3S4（LXME）（3）]（+）（X = S（1（+）），SE（2（+）））（2（+））） （9）]（4+）用适当的Schiff碱配体在甲醇中。 1-PF6的单晶X射线结构分析显示，一个Schiff基碱配体通过O，N和SME供体原子坐标，然后单阳离子簇[MO3S4（LSME）（3）]（+ ）如果没有考虑协调的硫原子周围的手性，则具有假C-3对称性。由于不对称席夫底座配体的布置，这种单放簇可能采用两个轴向手册中的一种。此外，复杂阳离子中三个协调中小企业基团的每种硫原子也是手性，这是在单位细胞中观察到的两个对映体的细胞。使用可变温度NMR光谱的线形分析检查络合物1-PF6和2-PF6在溶液中的动态行为，显示1-PF6中S原子的手性反转的速率常数大于SE原子的速率常数2-PF6和1-PF6的Delta H双匕首值的差异（47.1kJmol（-1））和2-PF6（56.7 kJ摩尔（-1））和负Δ的双匕首值（-39.9和-57.5 jmol（-1）k-1分别为1-pf6和2-pf6）表明反演过程涉及金属中心和s或se原子之间的粘合切割，然后选择溶剂分子。使用循环伏安法评价1-PF6和2-PF6的电化学性质，这表明1（+）和2（+）显示出分配给正式Mo的连续两个可逆的单电子还原波（IV IV IV分别为/ mo（III IV IV）和MO（111 IV IV）/ MO（III III IV）伴侣。还使用CH 3 CO 2H或CF 3 CO 2H作为质子源检查1-PF6和2-PF6催化H +电荷的能力。值得注意的是，催化波的氧化还原电位取决于添加的酸的酸度。因此，在较强的三氟乙酸作为质子源存在下观察第一减少波的催化电流，而当使用较弱的乙酸时，将出现围绕第二减少波的电流。

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