结构性,光谱性和反应性特性之间的相关性,在一系列结构上相似的转移稳定的 ((III) - 基氧复合体内
Michael K Coggins1, Vlad Martin-Diaconescu, Serena DeBeer
1The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|February 26, 2013
概括
这项研究详细介绍了转移稳定的-氧化物 (Mn-OOR) 化合物,揭示了它们的结构,光谱和反应性之间的强烈相关性. 这些发现在实验中将结构性质与O-O键激活联系起来,这对于生物化学和合成过程至关重要.
科学领域:
- 无机化学 无机化学
- 有机金属化学 有机金属化学
- 反应机制 反应机制
背景情况:
- -氧化物 (Mn-OOR) 物种是许多生化和合成反应中的重要中间体.
- 了解这些转移稳定的化合物的结构,光谱和反应性是有限的,缺乏实验相关性.
- 目前对末端Mn (III) -η (I) -peroxo) 复合物的知识很少.
研究的目的:
- 为了合成和表征新型的转移稳定的Mn(III) -OOR化合物.
- 通过实验确定结构性,光谱性和反应性特性之间的相关性.
- 阐明热衰变的机制,并确定影响OO键激活的因素.
主要方法:
- 确定了四种新的Mn(III) -OOR化合物的晶体结构.
- 改变温度的动力学研究,以分析热衰变机制.
- 光谱分析 (UV-Vis,IR) 探测电子和振动特性.
- 理论计算以支持关于易斯酸度和O-O键激活的实验发现.
主要成果:
- 合成和结构性表征四个新的末端 (Mn) (III) (η) (I) (peroxo) 复合物,将已知的系列扩展到六个.
- 证明连接体骨干变化调节金属-连接体距离和电子特性,影响过氧结合和激活.
- 确定结构参数 (O-O 和 Mn···N 距离),光谱特征 (CT 波段能量, ν(O-O) 和动力数据 (激活参数) 之间的强相关性.
- 有证据表明,在热衰变过程中O-O键裂变的速度是有限的,同解裂被产品分析证实.
- 结构性和反应性质的调节由N-异环胺和配体骨干,与O-O键激活与金属离子易斯酸度相关.
- 对降低过氧激活的实验和理论支持与N-异环胺与金属离子的接近度增加相关,减少π捐赠.
结论:
- 这项研究提供了极少数的实验验证之一,用于在-复合体中进行结构-功能关系的验证.
- 证实O-O键裂变是这些Mn(III) -OOR化合物的热衰变中的速度限制步骤.
- 金属离子的易斯酸度受到连接体环境的影响,是这些系统中O-O键激活的关键决定因素.
相关概念视频
01:21Radical Oxidation of Allylic and Benzylic Alcohols
Activated manganese(IV) oxide can selectively oxidize allylic and benzylic alcohols via a radical intermediate mechanism. Primary allylic alcohols are oxidized to aldehydes, while secondary allylic alcohols yield ketones. The redox reaction of potassium permanganate with an Mn(II) salt such as manganese sulfate (under either alkaline or acidic conditions), followed by thorough drying, yields the oxidizing agent: activated MnO2. While MnO2 is insoluble in the solvents used for the reaction, the...
02:21Oxidation of Alkenes: Syn Dihydroxylation with Potassium Permanganate
Alkenes can be dihydroxylated using potassium permanganate. The method encompasses the reaction of an alkene with a cold, dilute solution of potassium permanganate under basic conditions to form a cis-diol along with a brown precipitate of manganese dioxide.
01:23Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
02:34Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
02:52Stereoisomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...