Effect of substituents （NH2,OH,F） on structures and stability of lithofluorosilylenoids

Isomeric structures and energies of three kinds of lithofluorosilylenoids, R\-2SiLiF (R=NH\-2, OH, F) were studied using the ab initio molecular orbital theory. The calculations show that thermal stability of the three membered ring structures of these three kinds of silylenoids decreases in the order of substituents NH\-2>OH>F because of the conjugation between NH\-2, OH or F and Si atom. The interaction of substituents R with Li atom makes R\-2SiLiF have a structure with two Li A Si F (A=N, O, F) four membered rings, which is the most stable of the isomers of each of three kinds of silylenoids and whose stability decreases in the order of substituents F>OH>NH\-2. Inductive effect of substituents influences the thermal stability of the linear structure of silylenoids.