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本文用X-射线光电子能谱(XPS)研究了二十种硅上带有不同取代基(R)的杂氮硅三环类化合物,并对其中R为F,Cl,Br,I,CH_3,H,CH=CH_2,CH_2Cl,CHCl_2等九种该类化合物做了EHMO(广义Hückel分子轨道法)理论计算处理。从杂氮硅三环类化合物各组成元素的XPS谱,不但再次证明了这类化合物分子中N→Si配位键的存在,并得到不同取代基(R)对N→Si配位键强度的影响。EHMO计算求得的原子净电荷(Q)与不同取代基(R)所引起的N_(1s)和Si_(2p)结合能位移有线性关系。而计算的键序能很好地预言实验中取代基(R)的改变对N→Si配位键强度的影响。同时计算表明,在该类化合物中,其N→Si配位键的强度约为相应的Si—O共价键平均键强的一半。
In this paper, twenty kinds of heterosilazanes with different substituents (R) on silicon have been studied by X-ray photoelectron spectroscopy (XPS) Nine compounds of H, CH = CH_2, CH_2Cl and CHCl_2 were calculated by EHMO (generalized Hückel molecular orbital method). From the XPS spectra of the various elements of the trisubstituted azacyclo-tricyclics, not only the existence of N → Si coordination bonds in the molecules of these compounds was proved again, but also the intensities of N → Si coordination bonds with different substituents (R) influences. The net atomic charge (Q) calculated by EHMO and the displacement of N_ (1s) and Si_ (2p) due to different substituents (R) have a linear relationship. The calculated bond order can predict well the effect of the change of substituent (R) on the strength of N → Si coordination bond in experiment. Simultaneous calculations show that the strength of N → Si coordination bonds in these compounds is about half the average bond strength of the corresponding Si-O covalent bonds.