Synthesis And Property Of [PCP] Pincer Silylene Cobalt（Ⅰ） Complexes

Compared with N-heterocyclic carbine（NHC）and organophosphine ligands,N-heterocyclic silylene（NHSi）has stronger σ-donating ability and π-backbond ability.so as a ligand,it may better regulate the properties of metal centers and make metal complexes show good properties.After decades of development,the number of NHSi metal complexes is increasing.Most of them have been applied in the field of catalysis and shown good activity and regioselectivity,but the involved fields are not deep or wide enough.Therefore,further exploring the potential characteristics of NHSi may develop more efficient catalytic systems.Organosilicon have important applications in industry,agriculture and medicine.Alkene hydrosilylation is one of the most direct methods to synthesize organosilicon compounds.In industry,platinum systems are used for alkene hydrosilylation,such as Speier and Karsted catalytic systems.The catalytic system showed high activity and good chemical selectivity,but the platinum catalytic system was toxic,expensive and non-recyclable.With the proposal of green energy economy,the catalytic system based on iron,cobalt and nickel has been developed continuously.Therefore,it is a major challenge for us to find alternatives to platinum catalytic system.In this thesis,N-heterocyclic chlorosilylene coordinated Co complexes 1,2,3 and 4 were synthesized with flexible POCOP as the skeleton,and their structures were confirmed by IR,NMR and X-Ray diffraction analysis.Complex 1 reacted with carbon monoxide at room temperature to obtain the carbon monoxide and silylene co-coordinated complex 5.Complex 5 is sensitive to air.The reaction between complex 1 and iodomethane was also explored.Due to the existence of silylene,the reaction took place as a single-electron oxidation addition reaction to produce divalent cobalt iodide 6.We believe that complex 6 has catalytic activity for hydrosilylation of alkene.The experimental results show that the catalytic system has a certain catalytic ability for alkene hydrosilylation.The hydrosilylation of styrene and diphenylsilane was catalyzed by 2 mol%catalyst at 70℃,and 85%conversion could be achieved in 30 h.