已经合成了4N四齿配体的钴(II)配合物,并已表征为一步合成苯酚的催化剂。配合物的分子结构显示出方形金字塔形和三角形双锥体之间的几何形状(τ,0.49–0.88),Co–N胺和Co–N Py的键距分别为2.104–2.254Å和2.043–2.099Å。与乙腈中的Ag / Ag +相比,该复合物表现出的Co 2+ / Co 3+氧化还原电位约为0.489–0.500V 。H 2 O 2络合物催化苯的羟基化(30%)并选择性地提供苯酚作为主要产物。在60°C时,苯酚的最大收率可达29%,周转数(TON)为286,在25°C时,收率可达19%,TON值为191。迄今为止,这是使用钴(II)配合物作为催化剂报道的最高催化性能。该芳族羟基化大概是通过钴(III)-氢过氧化物进行的,其特征在于ESI-MS,振动和电子光谱方法。关键中间体[(L)Co III(OOH)] 2+的形成伴随着特征性的O→C
characterized as efficientcatalysts for the hydroxylation of benzene using H2O2. All the complexes exhibited Ni2+ → Ni3+ oxidation potentials of around 0.966–1.051 V vs. Ag/Ag+ in acetonitrile. One of the complexes has been structurally characterized and adopted an octahedral coordination geometry around the nickel(II) center. The complexes catalysed directbenzenehydroxylation using H2O2 as an oxygen
已经合成了N 4配体的镍(II)配合物,并表征为使用H 2 O 2进行苯羟基化的有效催化剂。与乙腈中的Ag / Ag +相比,所有络合物均显示出约0.966–1.051 V的Ni 2 + →Ni 3+氧化电位。其中一种配合物的结构已得到表征,并采用了围绕镍(II)中心的八面体配位几何形状。配合物使用H 2 O 2催化直接苯羟基化作为一种氧源,苯酚的含量高达41%,周转数(TON)为820。这是迄今为止使用0.05 mol%的催化剂负载量和5当量的H 2 O 2达到苯羟基化的最高催化效率。苯的羟基化反应可能通过关键的中间体双(μ-氧代)dinickel(III)进行,该化合物通过HR-MS,振动和电子光谱方法对几乎所有配合物进行了表征。关键中间体的形成常数计算为5.61-9.41×10个-2小号-1由以下的外观的氧代-对-镍(III)约406–413 nm的LMCT波段。发现中间体的寿命很短(t
Synthesis and characterization of copper complexes with a series of tripodal amine ligands
作者:Frank Mehlich、Asha E. Roberts、Marion Kerscher、Peter Comba、Geoffrey A. Lawrance、Christian Würtele、Jonathan Becker、Siegfried Schindler
DOI:10.1016/j.ica.2018.11.032
日期:2019.2
Abstract A series of copper complexes with tripodal amine ligands was synthesized and structurally characterized. The copper(I) complexes of this series were investigated in regard to their reactivity towards dioxygen using stopped-flow techniques. For most complexes no “dioxygen adduct” complexes as intermediates could be detected. During the course of our investigations it was observed that the copper(II)
Cu-Namine bonds (2.01-2.148 Å). Also, their Cu-O (Cu-Owater, 1.988 Å; Cu-Otriflate, 2.33 Å) bond distances are slightly varied. All of the complexes exhibited Cu2+ → Cu+ redox couples in acetonitrile, where the redoxpotentials of TBP-based complexes (-0.251 to -0.383 V) are higher than those of SP-based complexes (-0.450 to -0.527 V). The d-d bands around 582-757 nm and axial patterns of electron paramagnetic
Novel nickel(II)-N4 complexes are reported as highly efficient catalysts for the green conversion of CO2 into five-membered cyclic carbonates with superior selectivity under 1 atm air/CO2 at room temperature.
据报道,新型镍 (II)-N 4配合物是在室温下 1 atm 空气/CO 2条件下将 CO 2绿色转化为五元环状碳酸酯的高效催化剂,具有优异的选择性。
Mechanistic studies on catalytic alkane oxidation by Murahashi's O<sub>2</sub>/copper(<scp>ii</scp>)/aldehyde system
(ketone) in a 1 : 1 ratio as the oxidation products. The acyloxyl intermediate RC(O)O˙ also reacts with RCHO to give carboxylic acid RC(O)OH and RC(O)˙, constructing the catalytic cycle. The role of copper(II) ions in the above catalytic process is also investigated using a series of copper(II) complexes. Furthermore, Murahashi's system was adopted in the catalyticoxidation of methane.
Murahashi 的 O 2 /铜( II )/醛体系催化烷烃羟基化的机理研究表明,醛 (RCHO) 通过产生 O 2 的酰基自由基中间体 (RC(O)˙) 的自氧化涉及如下:催化循环的起始步骤。生成的RC(O)˙被O 2捕获,得到酰基过氧自由基中间体RC(O)OO˙,其可以与另一个RCHO反应生成加合物中间体RC(O)OOC(R)(H)O˙。该中间体随后的 O-O 键均裂将得到酰氧基中间体 RC(O)O˙ 和 RCOOH,其中前者充当从烷烃底物 (R 1 R 2 CH2 ; R 1和R 2为烷基或氢原子,得到R 1 R 2 CH˙。生成的R 1 R 2 CH˙与O 2反应生成烷基过氧自由基中间体R 1 R 2 CHOO˙,再进行Russell反应生成R 1 R 2 CHOH(醇)和R 1 R 2 CO(酮)以 1:1 的比例作为氧化产物。酰氧基中间体RC(O)O˙也与RCHO反应生成羧