Autocorrelation Topological Research of the First Ionization Potentials for Haloalkanes

The atomic ordinal numbergiand its colouring numbergi′based on the systematic nomenclature of organic compound have excellent selectivity for non-hydrogen atom in organic molecules, and mirror its chemical surroundings. The first order autocorrelation topological index 1Gand its colouring index1G′of atomic ordinal number are defined as:1G=∑(gigj)-1,1G′=∑(gi′gj′)-1.1Gand1G′are very easy to be calculated and have good discrimination (better than the famous Kier′s index1Xv) between isomeric alkanes and haloalkanes. It can be expressed as following equation for the change rule of the first ionizating potentialIpfor 27 haloalkanes: Ip=7.4545-0.79341G′-0.70671G+1.5514Xp,　R =0.9982 WhereXpis the electronegativity of halogen atom. This correlativity is surpass than that of the literature. The estimated results by above equation are satisfactory.