パラジウム (((II) 水素結合に分子酸素を挿入する
Melanie C Denney1, Nicole A Smythe, Kara L Cetto
1Department of Chemistry, University of Washington, Seattle, 98195-1700, USA.
Journal of the American Chemical Society
|February 24, 2006
まとめ
研究者らは,パラジアム−ヒドリド結合に酸素を挿入することによって,パラジアム−ヒドリド複合体の形成を報告している. この反応は,パラジウムと酸素の両方において第1次反応であり,Pd-H結合の分裂が重要なことを示している.
科学分野:
- 有機金属化学 有機金属化学
- 無機化学 無機化学とは
- カタリシス カタリシス カタリシス
背景:
- パラジウム複合体は,触媒作用において不可欠である.
- パラジウムヒドリド結合の反応性を理解することは,触媒機構にとって極めて重要です.
- パラジウム複合体の分子酸素との相互作用は,多くの酸化触媒サイクルにおける重要なステップです.
研究 の 目的:
- パラジウム (((II) 水素複合体と分子酸素の反応を調査する.
- その結果生じるパラジウム-酸素種を特徴づけるために.
- Pd-H結合に酸素が挿入されるメカニズムを解明する.
主な方法:
- パラジウム (((II) 水素の前駆体とO2の反応.
- 製品の特徴化のためのX線結晶学.
- 速度の法則を決定するための運動学的研究.
- ラジカル阻害剤と光への曝露を用いた研究.
主要な成果:
- (eta1-hydroperoxo) パラジウム (II) 複合体の形成.
- 水素ペロキソ複合体の結晶学的な特徴.
- 二次値法則 (パラジウムでは第一位,酸素では第一位).
- 有意な運動同位体効果 (KIE) は,速度決定のステップで Pd-H 結合の割れ方を示唆しています.
- 阻害剤と光の研究に基づく,ラジカルチェーンメカニズムに対する証拠.
結論:
- 分子酸素はパラジウム (((II) 水素結合に挿入し,水素ペロキソ複合体を形成する.
- 反応のメカニズムは,速度を決定する Pd-H 結合の割れを伴う.
- 反応は,根幹経路を通って進まない.
関連する概念動画
02:46Covalent Bonding and Lewis Structures
Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual attraction of atoms for a “shared” pair of electrons.
02:54Lewis Structures of Molecular Compounds and Polyatomic Ions
To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
01:19Oxidation and Reduction of Organic Molecules
Energy production within a cell involves many coordinated chemical pathways. Most of these pathways are combinations of oxidation and reduction reactions, which occur at the same time. An oxidation reaction strips an electron from an atom in a compound, and the addition of this electron to another compound is a reduction reaction. Because oxidation and reduction usually occur together, these pairs of reactions are called redox reactions.
The removal of an electron from a molecule, results in a...
The removal of an electron from a molecule, results in a...
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.
01:19Diazonium Group Substitution: –OH and –H
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.