Cp (ph <sub> 3 </ Sub> P) Ru (sime <sub> 2 </ Sub> Osime <sub> 2 </ Sub>) And Roh (r = Ch <sub> 3 </ Sub> Oh , H <sub> 2 </ Sub> O) Reaction Mechanism Theoretical Research

Over the past few decades,considerable attention has been focused on the chemistry of silylene complexes,such as dehydrogenative coupling of hydrosilanes,redistribution of substituents on silicon atoms and silylene transfer to unsaturated organic compounds.These complexes undergo intramolecular 1,3-migration,which is postulated as a key step in the metal-mediated redistribution of substituents on organosilicon compounds.Ogino group have successfully synthesized and characterized a series donor-bridged bis(silylene) transition-metal complexes in decades.Among these donor-bridged complexes,alkoxy-bridged bis(silylene) transition-metal complexes,with peculiar bond modes and novel reactivity,occupy a unique position in these systems.The silicon atom is expected to be vulnerable to various nucleophiles such as ROH,RCN,H₂O,etc.This kind of nucleophilic reactions should be one of the most common reactions of silylene complexes.Thus,it will be very interesting and of guiding meaning to make theoretical study on silametallacycles complexes.In this paper,we use Density functional theory(DFT) calculations at the B3LYP level to study and analyze the following project.Our major intention is to investigate the molecular structures,bonding,and mechanisms on the reactions of the organometallic complexes mentioned below.The reaction mechanism of the Cp(Ph₃P)Ru(SiMe₂OSiMe₂) and ROH(R=CH₃OH,H₂O) is studied by modeling reaction between Cp(Ph₃P)Ru(SiMe₂OSiMe₂)(Cp means cyclopentadienyl anion) and methanol using DFT computational method.Geometrical and bonding character of the corresponding complexes discussed here is analyzed carefully.Two possible reaction mechanisms are provided by us as follows:a) ROH attack from the front face; b) ROH attack from the side face.Detailed computational results show that front face attack is much favorable for both of the CH₃OH and H₂O cases though their final products are not similar with each other.This can be attributed for following two reasons:a) the fist intermediate of the H₂O attack reaction is energetically favorable than that of the CH₃OH attack reaction,which lead to the lower energies for those subsequential intermediates,and then make the reaction much easier to proceed;b) the structural difference of the fourth intermediate,it is the last product for CH₃OH,but it is only a intermediate for H₂O.As a result,the product of H₂O and Cp(Ph₃P)Ru(SiMe₂OSiMe₂)reaction is much thermodynamic stable than that of CH₃OH attack reaction.Then,the difference between those two reactions can be explained very well from dynamic as well as thermodynamic studies,which is agreement very well with experimental conclusions.