Addition reaction of pentacoordinated silicon compounds by R3SiX with NR3'

The adducts R3SiX-NR3'(R=H, CH3; X=F, Cl, Br, I; R'=H, CH3) formed in two addition modes were studied with DFT at B3LYP/6-31g(d,p) level (X atoms used the cep-121g base-set): one type was the adducts approached axially along the Si-X bond, the other type was the adducts approached laterally along the Si-X bond. The computed results showed that the former was more stable and more easily to be formed. The presence of group with pushing electron effect on Si made it difficult to form Si-N bond and the reverse was true on NR3'. NH3-H3SiX and N(CH3)(3)-H3SiX series can form two kinds of adducts. NH3-H-2(CH3)SiX series can only form one kind of adduct. NH3-H(CH3)(2)SiX and NH3-(CH3)(3)SiX series can not form any adducts. The adduct of X=Cl is the most stable one in the same series. The bonding properties of all the adducts, the change of NBO charges, the influence of various halogen atoms and methyl on the structures and the stability of adducts were analyzed. The possibility of being conductive of adducts H3SiX-NH3 and H3SiX-N(CH3)(3) in organic solvents was also discussed.