Distinct Catalytic Performance of Cobalt(I)–<i>N</i>-Heterocyclic Carbene Complexes in Promoting the Reaction of Alkene with Diphenylsilane: Selective 2,1-Hydrosilylation, 1,2-Hydrosilylation, and Hydrogenation of Alkene
作者:Yafei Gao、Lijun Wang、Liang Deng
DOI:10.1021/acscatal.8b02513
日期:2018.10.5
selectivity in catalyzing the reaction of alkene with Ph2SiH2. [(IAd)(PPh3)CoCl] (IAd = 1,3-diadamantylimidazol-2-ylidene) is an efficient catalyst for anti-Markovnikov hydrosilylation of monosubstituted alkenes. [(IMes)2CoCl] (IMes = 1,3-dimesitylimidazol-2-ylidene) shows Markovnikov-addition selectivity in promoting the hydrosilylation of aryl-substituted alkenes. [(IMe2Me2)4Co][BPh4] (IMe2Me2 = 1,3-dimethyl-4
solvent-free cobalt-catalyzed highly selective hydrosilylation of alkenes has been developed. It was found that both Co(PMe3)4 and CoCl(PMe3)3 are highly active catalysts for hydrosilylation of alkenes. The former promoted Markovnikov-type hydrosilylation of the aryl alkenes, while the latter catalyzed anti-Markovnikov-type hydrosilylation of the alkyl alkenes. These two catalytic systems tolerate a variety
unsymmetrical N-heterocyclic carbene (NHC) [CNC]-pincer preligands with CoMe(PMe3)4 gave rise to NHC [CNC]-pincer cobalt(III) hydrides, [(CcarbeneNaminoCnaphthyl)Co(H)(PMe3)2] (3a) and (3b), via Csp2–H activation and the unexpected trans-bischelate [Ccarbene, Namino] cobalt(II) complexes 4a and 4b via a disproportionation reaction, respectively. It was found that both 3a and 3b are efficient catalysts
The Effect of Substituents on the Formation of Silyl [PSiP] Pincer Cobalt(I) Complexes and Catalytic Application in Both Nitrogen Silylation and Alkene Hydrosilylation
effect of substituents at P and/or Si atom of the [PSiP] pincer ligands on the formation of silyl cobalt(I) complexes by the reactions with CoMe(PMe3)4 via Si–H cleavage. Two penta-coordinated silyl cobalt(I) complexes, (2-Ph2PC6H4)2HSiCo(PMe3)2 (1) and (2-Ph2PC6H4)2PhSiCo(PMe3)2 (2), were obtained from the reactions of L1 and L2 with CoMe(PMe3)4, respectively. Under similar reaction conditions, a tetra-coordinated
四种不同的[PSiP] -pincer配体L1 - L4((2-Ph 2 PC 6 H 4)2 SiHR(R = H(L1)和Ph(L2))和(2- i Pr 2 PC 6 H 4)2使用SiHR'(R'= Ph(L3)和H(L4))研究[PSiP]钳形配体的P和/或Si原子上的取代基对甲硅烷基钴(I)配合物形成的影响。通过Si–H裂解与CoMe(PMe 3)4反应。两个五配位的甲硅烷基钴(I)配合物(2-Ph 2从L1和L2与CoMe(PMe)反应获得PC 6 H 4)2 HSiCo(PMe 3)2(1)和(2-Ph 2 PC 6 H 4)2 PhSiCo(PMe 3)2(2)3)4。在相似的反应条件下,四配位钴(I)配合物(2- i Pr 2 PC 6 H 4)2 PhSiCo(PMe 3)(3)是从L3与CoMe(PMe 3)4的相互作用中分离出来的。发现仅在配体L4的情况下,形成甲硅烷基二氮钴(I)络合物4
[P,C]-Chelate Cobalt(III) Hydride Catalyzed Hydrosilylation of Alkenes
CoCl(PMe3)3 to give [P,C]-chelate cobalt(III) hydrides [mer-(Me3P)3Co(H)(Cl)(o-Ph2P–C6H4–C═O)] (1) or [mer-(Me3P)3Co(H)(Cl)(o-iPr2P–C6H4–C═O)] (2), respectively. Complex 2 was new and characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. It was found that both complex 1 and 2 are active catalysts for hydrosilylation of alkenes. Although the catalyticactivity of 1 is slightly
双齿配体 2-二苯基膦基苯甲醛或 2-二异丙基膦基苯甲醛与 CoCl(PMe 3 ) 3反应得到 [P,C]-螯合钴 (III) 氢化物 [ mer -(Me 3 P) 3 Co(H)(Cl)( o - Ph 2 P–C 6 H 4 –C=O)] ( 1 ) 或 [ mer -(Me 3 P) 3 Co(H)(Cl)( o - i Pr 2 P–C 6 H 4 –C=O )] ( 2 ) 分别。复合体2是新的,并通过光谱方法和单晶 X 射线衍射分析进行表征。发现配合物1和2都是烯烃氢化硅烷化的活性催化剂。虽然催化活性1略高,催化剂1和2具有相同的选择性。芳香族烯烃的选择性主要是马尔可夫尼科夫型,而脂肪族烯烃的选择性几乎是 100% 的反马尔可夫尼科夫型。在反应机理研究中,从氢化物1的化学计量反应中分离出甲硅烷基二氢化钴[(Ph 2 ClSi)Co(H) 2 (PMe 3 ) 3 ]与Ph 2