Hydride Abstraction from 1,2-Diols by the Pentaaqua(oxo)chromium(IV) Ion
摘要:
Kinetic studies of the oxidation of 1,2-diols by the pentaaqua(oxo)chromium(IV) ion, (H2O)5Cr(IV)=O2+, were carried out in dilute aqueous solutions of perchloric acid. These reactions yield the superoxochromium(III) ion CrOO2+, providing evidence that the two-electron reduction of Cr(IV)O2+ to Cr2+ occurred in a single step. The rate constants for the primary and secondary diols are comparable to each other and approximately 10 times larger than that for pinacol (k = 3.7 L mol-1 s-1). The kinetic isotope effect of the O-H hydrogens is negligible, k(H)/k(D) = 0.95-1.3, whereas that for the C-H hydrogens is substantial, k(H)/k(D) = 3.7-4.8. A 2-equiv mechanism is proposed, in which CrO2+ abstracts a hydride ion from an a-position in the primary and secondary diols and from alpha,beta-position in pinacol.
Kinetics of the electron-transfer reactions of tetranuclear isomeric species of cobalt(III)-ammine complexes with hexaaquochromium(II) and hexaaquovanadium(II) ions
作者:Ademir Neves、Cesar V. Franco
DOI:10.1016/s0020-1693(00)80590-3
日期:1989.6
through the organic ligands are assigned for complexes II , III and IV . Due to steric hindrance by carboxylate groups, an outer-sphere mechanism is observed for complex I . The electron-transfer rates for complexesIII and IV are 20–50 times faster than that in complex II , and are discussed in terms of the lowering of the energy barrier caused by a significant π orbital interaction of oxidant and reductant
摘要Cr(OH 2)6 2+和V(OH 2)6 2+配合物与具有2,6-,3,5-吡啶基的钴(III)-胺配合物的四核异构体的电子转移反应动力学,已在具有各种氢离子浓度的溶液中研究了2,4-和2,5-二羧酸二桥联配体(I-IV)。对于配合物II,III和IV,定义了在去质子化的远端吡啶氮原子上具有Cr(II)攻击和随后通过有机配体进行电子转移的内层机理。由于羧酸根基团的位阻,观察到复合物I的外球机理。配合物III和IV的电子传输速率比配合物II快20-50倍,讨论了通过氧化剂和还原剂通过杂环桥配体的显着π轨道相互作用而引起的能垒降低。基于ak Cr / k V比0.026分配用于降低I的外层机制。V(II)对络合物II的还原与[H +]无关,并且由外球进行。
Nucleobase Oxidation of DNA by (Terpyridyl)chromium(
<scp>III</scp>
) Derivatives
作者:Vaidyanathan Ganesan Vaidyanathan、Balachandran Unni Nair
DOI:10.1002/ejic.200300718
日期:2004.5
binders of calf thymus DNA (CT DNA), while viscosity measurements show that they bind with partial intercalation. Binding of the two chromium complexes to DNA and mononucleotides dGMP, dAMP, dCMP, and dTMP decreases the emission intensity of complex 2. However, the emission intensity of complex 1 is quenched only by DNA and the nucleotides dGMP and dAMP. Excited state potentials of both 1 and 2 have been
Fast Ligand Substitution at a Chromium(III) Hydroperoxo Complex
作者:Wenjing Song、Andreja Bakac
DOI:10.1021/ic9016799
日期:2010.1.4
and sulfate) at rates that are unprecedented for substitution at a pentaaquachromium(III) complex. The chemistry is noteworthy in that it interchanges low-concentration, weak ligands between a Cr(III) coordination sphere and solution in the presence of a large excess of water. We attribute this chemistry and the fast kinetics to the hydroperoxo cis effect. Each of the entering anions follows a different
(H 2 O)5 CrOOH 2+中的氢过氧取代基被选定的阴离子(乙酸根,硝酸根和硫酸根)取代,其取代率在五甲基四铬(III)络合物中是空前的。该化学值得注意,因为它在大量过量的水存在下在Cr(III)配位球和溶液之间交换了低浓度的弱配体。我们将此化学反应和快速动力学归因于氢过氧顺式作用。在支撑H的每个进入的阴离子的遵循不同的速率定律+从混合配体中间的氢过组的解离-assisted。对[H +]对于硝酸盐而言是一阶,对于乙酸而言是零阶,并且在0.015 M <[H + ] <0.20 M的酸度范围内,对于硫酸盐从一阶变为零阶。在1.0 MH +时,第二阶速率常数为3.0(硝酸根),2.49(硫酸根)和0.90(乙酸)M -1 s -1。速率常数的相似性支持以铬为限速取代为特征的机理。的平衡常数的反应(H 2 O)5 CrOOH 2+ + NO 3 - + H + ⇄(H 2 O)5 CRONO
Ligand Dissociation Rate Constants of Tris(4,4′-dimethyl-2,2′-bipyridine)chromium(II) and Tris(5,5′-dimethyl-2,2′-bipyridine)chromium(II) Complexes
作者:Kunio Nakano、Yoshio Narusawa、Hiroyuki Moroi
DOI:10.1246/bcsj.54.2529
日期:1981.8
Ligand dissociations of tris(4,4′-Me2bpy)- and tris(5,5′-Me2bpy)chrornium(II) complexes have been studied by scavenging the ligand with zinc ion according to a stopped-flow method.
已经通过根据停流方法用锌离子清除配体来研究三 (4,4'-Me2bpy)- 和三 (5,5'-Me2bpy) 铬 (II) 配合物的配体解离。
Reactions of thiyl radicals with transition-metal complexes
作者:Patrick Huston、James H. Espenson、Andreja Bakac
DOI:10.1021/ja00050a033
日期:1992.11
of thiyl radicals (RS . ) were studied in aqueous solution by laser flash photolysis. Alkyl radicals, which were used to generate the thiyl radicals, were produced by the photohomolysis of the cobalt-carbon bond of RCo([14]aneN 4 )(H 2 O) 2+ complexes (R=CH 3 , C 2 H 5 ). These carbon-centeredradicals abstract hydrogen atoms from thiols (C 2 H 5 SH, CysSH, or GSH), generating thiyl radicals. Thiyl radicals
通过激光闪光光解在水溶液中研究了硫基自由基 (RS . ) 的反应。用于生成硫基自由基的烷基自由基是通过 RCo([14]aneN 4 )(H 2 O) 2+ 配合物 (R=CH 3 , C 2 H 5 ) 的钴-碳键的光均分解产生的)。这些以碳为中心的自由基从硫醇(C 2 H 5 SH、CysSH 或 GSH)中提取氢原子,生成硫基自由基。硫基自由基很容易氧化各种还原的过渡金属配合物