当前位置：
X-MOL 学术
›
Organometallics
›
论文详情
Our official English website, www.x-mol.net, welcomes your
feedback! (Note: you will need to create a separate account there.)
Kinetics and Mechanism of Isocyanide-Promoted Carbene Insertion into the Aryl Substituent of an N-Heterocyclic Carbene Ligand in Ruthenium-Based Metathesis Catalysts
Organometallics ( IF 2.5 ) Pub Date : 2017-08-16 00:00:00 , DOI: 10.1021/acs.organomet.7b00342 Justin R. Griffiths 1 , Elan J. Hofman 1 , Jerome B. Keister 1 , Steven T. Diver 1
Organometallics ( IF 2.5 ) Pub Date : 2017-08-16 00:00:00 , DOI: 10.1021/acs.organomet.7b00342 Justin R. Griffiths 1 , Elan J. Hofman 1 , Jerome B. Keister 1 , Steven T. Diver 1
Affiliation
|
In situ IR spectroscopy was used to study the kinetics of addition of L = alkyl and aryl isocyanides to the Grubbs second-generation carbene complex Ru(H2IMes)(CHPh)(PCy3)Cl2 (H2IMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene), which triggers carbene insertion into an aromatic ring of the N-heterocyclic carbene supporting ligand, forming Ru{1-mesityl-3-(7′-Ph-2′,4′,6′-trimethylcycloheptatrienyl)-4,5-dihydroimidazol-2-ylidene}L2(PCy3)Cl2. The rate law was determined to be first order in isocyanide concentration and first order in carbene complex concentration. For various isocyanides CNR the rate increases as R = tert-butyl ≪ cyclohexyl < n-octyl < CH2Ph ≈ CH2CO2Me ≈ CH2SO2C6H4-4-Me < C6H4-4-OMe < C6H4-4-Cl. The proposed mechanism involves reversible addition of isocyanide followed by rate-determining, irreversible carbene insertion and subsequent, rapid addition of the second isocyanide. The carbene insertion is accelerated by the electrophilicity of the carbene, which is enhanced due to ligand binding by isocyanides with lower σ-donor/π-acceptor ratios.
中文翻译：
钌基复分解催化剂中异氰酸酯促进的碳插入N-杂环碳配体芳基取代基的动力学和机理
使用原位红外光谱研究了将L =烷基和芳基异氰酸酯添加到Grubbs第二代卡宾络合物Ru（H 2 IMes）（CHPh）（PCy 3）Cl 2（H 2 IMes = 1,3 -dimesityl-4,5-dihydroimidazol-2-ylidene），触发卡宾插入N杂环卡宾支持配体的芳香环，形成Ru {1-mesityl-3-（7'-Ph-2'，4 ′，6′-三甲基环庚三烯基）-4，5-二氢咪唑-2-亚基} L 2（PCy 3）Cl 2。速率定律被确定为异氰化物浓度为一阶，卡宾络合物浓度为一阶。对于各种异氰化物，CNR的比率随着R =叔数的增加而增加丁基≪环己基<正辛基<CH 2 Ph≈CH 2 CO 2 Me≈CH 2 SO 2 C 6 H 4 -4-Me <C 6 H 4 -4-OMe <C 6 H 4 -4-Cl。所提出的机理涉及可逆地添加异氰酸酯，然后确定速率，不可逆的卡宾插入以及随后快速添加第二种异氰酸酯。卡宾的亲电性通过卡宾的亲电性加速卡宾的插入，由于具有较低的σ-供体/π-受体比的异氰酸酯与配体的结合而增强了卡宾的亲电性。
更新日期：2017-08-16
中文翻译：
钌基复分解催化剂中异氰酸酯促进的碳插入N-杂环碳配体芳基取代基的动力学和机理
使用原位红外光谱研究了将L =烷基和芳基异氰酸酯添加到Grubbs第二代卡宾络合物Ru（H 2 IMes）（CHPh）（PCy 3）Cl 2（H 2 IMes = 1,3 -dimesityl-4,5-dihydroimidazol-2-ylidene），触发卡宾插入N杂环卡宾支持配体的芳香环，形成Ru {1-mesityl-3-（7'-Ph-2'，4 ′，6′-三甲基环庚三烯基）-4，5-二氢咪唑-2-亚基} L 2（PCy 3）Cl 2。速率定律被确定为异氰化物浓度为一阶，卡宾络合物浓度为一阶。对于各种异氰化物，CNR的比率随着R =叔数的增加而增加丁基≪环己基<正辛基<CH 2 Ph≈CH 2 CO 2 Me≈CH 2 SO 2 C 6 H 4 -4-Me <C 6 H 4 -4-OMe <C 6 H 4 -4-Cl。所提出的机理涉及可逆地添加异氰酸酯，然后确定速率，不可逆的卡宾插入以及随后快速添加第二种异氰酸酯。卡宾的亲电性通过卡宾的亲电性加速卡宾的插入，由于具有较低的σ-供体/π-受体比的异氰酸酯与配体的结合而增强了卡宾的亲电性。
京公网安备 11010802027423号