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Oxygen Atom Transfer Reactivity of Molybdenum(VI) Complexes Employing Pyrimidine- and Pyridine-2-thiolate Ligands.
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2020-09-21 , DOI: 10.1021/acs.inorgchem.0c02412
Madeleine A Ehweiner 1 , Fabian Wiedemaier 2 , Ferdinand Belaj 1 , Nadia C Mösch-Zanetti 1
Affiliation  

Four dioxidomolybdenum(VI) complexes of the general structure [MoO2L2] employing the S,N-bidentate ligands pyrimidine-2-thiolate (PymS, 1), pyridine-2-thiolate (PyS, 2), 4-methylpyridine-2-thiolate (4-MePyS, 3) and 6-methylpyridine-2-thiolate (6-MePyS, 4) were synthesized and characterized by spectroscopic means and single-crystal X-ray diffraction analysis (24). Complexes 14 were reacted with PPh3 and PMe3, respectively, to investigate their oxygen atom transfer (OAT) reactivity and catalytic applicability. Reduction with PPh3 leads to symmetric molybdenum(V) dimers of the general structure [Mo2O3L4] (69). Kinetic studies showed that the OAT from [MoO2L2] to PPh3 is 5 times faster for the PymS system than for the PyS and 4-MePyS systems. The reaction of complexes 13 with PMe3 gives stable molybdenum(IV) complexes of the structure [MoOL2(PMe3)2] (1012), while reduction of [MoO2(6-MePyS)2] (4) yields [MoO(6-MePyS)2(PMe3)] (13) with only one PMe3 coordinated to the metal center. The activity of complexes 14 in catalytic OAT reactions involving Me2SO and Ph2SO as oxygen donors and PPh3 as an oxygen acceptor has been investigated to assess the influence of the varied ligand frameworks on the OAT reaction rates. It was found that [MoO2(PymS)2] (1) and [MoO2(6-MePyS)2] (4) are similarly efficient catalysts, while complexes 2 and 3 are only moderately active. In the catalytic oxidation of PMe3 with Me2SO, complex 4 is the only efficient catalyst. Complexes 14 were also found to catalytically reduce NO3 with PPh3, although their reactivity is inhibited by further reduced species such as NO, as exemplified by the formation of the nitrosyl complex [Mo(NO)(PymS)3] (14), which was identified by single-crystal X-ray diffraction analysis. Computed ΔG values for the very first step of the OAT were found to be lower for complexes 1 and 4 than for 2 and 3, explaining the difference in catalytic reactivity between the two pairs and revealing the requirement for an electron-deficient ligand system.

中文翻译:

使用嘧啶-和吡啶-2-硫醇盐配体的钼(VI)配合物的氧原子转移反应性。

具有S,N-二齿配体嘧啶-2-硫醇盐(PymS,1),吡啶-2-硫醇盐(PyS,2),4-甲基吡啶-的S,N-双齿配体的四种通用结构[MoO 2 L 2 ]的二氧化钼(VI)配合物2-硫醇(4- MePyS,3)和6-甲基吡啶-2-硫醇(6-MePyS,4)被合成和表征通过光谱方法和单晶X射线衍射分析(2 - 4)。配合物1 - 4与PPH进行反应3和PME 3,分别调查其氧原子转移(OAT)的反应性和催化的适用性。用PPh还原3所导致对称钼(V)的一般结构的二聚物[沫2 ö 3大号4 ](6 - 9)。动力学研究表明,对于PymS系统,从[MoO 2 L 2 ]到PPh 3的OAT速度比PyS和4-MePyS系统快5倍。复合物的反应1 - 3用Pme 3给出稳定钼(IV)结构的配合物[MOOL 2(PME 32 ](10 - 12),而减少[的MoO的2(6- MePyS)2](4)产生[MoO(6-MePyS)2(PMe 3)](13),其中只有一个PMe 3与金属中心配位。复合物的活性1 - 4在涉及我催化OAT反应2 SO且Ph 2 SO如氧施主和PPH 3作为氧受体已被研究以评估OAT反应速率的变化的配体框架的影响。发现[MoO 2(PymS)2 ](1)和[MoO 2(6-MePyS)2 ](4)是同样有效的催化剂,而配合物23只是中等活性。在用Me 2 SO催化PMe 3催化氧化中,配合物4是唯一有效的催化剂。配合物1 - 4也被发现催化还原NO 3 -以PPH 3,尽管它们的反应性,通过进一步降低的物种,如NO抑制由亚硝酰复合物的形成所示例[沫(NO)(PymS)3 ](14),其通过单晶X射线衍射分析鉴定。计算出的Δ ģ 被发现为OAT的第一步值成为络合物下部1423,解释在两对之间的催化活性的差异,揭示用于缺电子配体系统的要求。
更新日期:2020-10-05
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