Axial Ligand Coordination to the C-H Amination Catalyst Rh2(esp)2: A Structural and Spectroscopic Study.
Axial Ligand Coordination to the C-H Amination Catalyst Rh2(esp)2: A Structural and Spectroscopic Study.
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C-H 胺化催化剂 Rh2(esp)2 的轴向配体配位：结构和光谱研究。
DOI：
10.1021/acs.inorgchem.5b01532
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发表时间：
2015
影响因子：
4.6
通讯作者：
J. Berry
中科院分区：
文献类型：
--
作者：
Evan J. Warzecha;Timothy C. Berto;J. Berry
化合物 Rh2(esp)2（esp = α,α,α',α'-四甲基-1,3-苯二丙酸酯）是 C-H 键氮烯类胺化最有效的催化剂。然而，其大部分基本配位化学尚不清楚。在这项工作中，我们研究了轴向配体配位对催化剂 Rh2(esp)2 的影响。我们在此报告了配合物 Rh2(esp)2L2 的晶体结构、循环伏安法、紫外-可见光、红外、拉曼和 (1)H NMR 光谱，其中 L = 吡啶、3-甲基吡啶、2,6-二甲基吡啶、乙腈和甲醇。这些化合物均在16500至20500 cm(-1)范围内显示出明确的π*→σ*电子跃迁，在304至322 cm(-1)范围内显示出Rh-Rh伸缩振动。考虑到这些数据，我们发现轴向配体与 Rh2(esp)2 结合的强度在 CH3OH ∼ 2,6-二甲基吡啶 < CH3CN < 3-甲基吡啶 ∼ 吡啶系列中增加。仅当存在乙腈或不存在轴向配体时才能获得准可逆的 Rh2(4+/5+) 氧化还原波。在吡啶存在的情况下，观察到不可逆的氧化波，表明这些配体在氧化条件下使 Rh2 复合物不稳定。
The compound Rh2(esp)2 (esp = α,α,α',α'-tetramethyl-1,3-benzenediproponoate) is the most generally effective catalyst for nitrenoid amination of C-H bonds. However, much of its fundamental coordination chemistry is unknown. In this work, we study the effects of axial ligand coordination to the catalyst Rh2(esp)2. We report here crystal structures, cyclic voltammetry, UV-vis, IR, Raman, and (1)H NMR spectra for the complexes Rh2(esp)2L2 where L = pyridine, 3-picoline, 2,6-lutidine, acetonitrile, and methanol. The compounds all show well-defined π* → σ* electronic transitions in the 16500 to 20500 cm(-1) range, and Rh-Rh stretching vibrations in the range from 304 to 322 cm(-1). Taking these data into account we find that the strength of axial ligand binding to Rh2(esp)2 increases in the series CH3OH ∼ 2,6-lutidine < CH3CN < 3-methylpyridine ∼ pyridine. Quasi-reversible Rh2(4+/5+) redox waves are only obtained when either acetonitrile or no axial ligand is present. In the presence of pyridines, irreversible oxidation waves are observed, suggesting that these ligands destabilize the Rh2 complex under oxidative conditions.
影响因子：
18.3
作者：
Roizen JL;Harvey ME;Du Bois J
通讯作者：
Du Bois J