卤代硅烷(R_3SiX)与NR′_3形成五配位硅化合物的加成反应

Addition Reaction of Pentacoordinated Silicon Compounds by R_3SiX with NR′_3

对R_3SiX(R=H、CH_3;X=F、Cl、Br、I)与NR3′(R′=H、CH_3)的加成物用量子化学密度泛函方法在B3LYP/6-31g(d,p)基组下(X原子采用cep-121g基组)进行了两种加成方式的研究.一种是NR′3沿Si—X键轴向位置的加成,另一种是NR3′沿Si—X键侧向接近的加成.计算结果表明,前者更稳定且更容易形成加成物;Si上斥电子基团不利于Si—N键的形成,而N上斥电子基团则有利于Si—N键的形成;NH3-H3SiX系列和N(CH3)3-H3SiX系列均能以两种方式进行加成,NH3-H2(CH3)SiX系列仅能沿Si—X键轴向进行加成,而NH3-H(CH3)2SiX和NH3-(CH3)3SiX系列两种方式都不能进行加成;在同系列加成产物中,以X=Cl时所得加成物最稳定.讨论了所有加成物中各键的性能、NBO电荷变化、取代基对加成物结构和稳定性的影响,并对H3SiX(X=F、Cl、Br、I)与NH3及N(CH3)3加成物在有机溶剂中导电的可能性进行了讨论.

The adducts R3SiX-NR＇3 （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 NR＇3 NH3-H3SiX and N（CH3）3-H3SiX series can form two kinds of adducts. NH3-H2（CH3）SiX series can only form one kind of adduct. NH3-H（CH3）2SiX and NH3-（CH3）3SiX 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.