DESIGN OF TOPOLOGICAL INDEXES - PART 10 - PARAMETERS BASED ON ELECTRONEGATIVITY AND COVALENT RADIUS FOR THE COMPUTATION OF MOLECULAR GRAPH DESCRIPTORS FOR HETEROATOM-CONTAINING MOLECULES

Two new approaches are presented for the calculation of atom and bond parameters for heteroatom-containing molecules used in computing graph theoretic invariants. In the first approach, the atom and bond weight s are computed on the basis of relative atomic electronegativity, usin g carbon as standard. In the second system, the relative covalent radi i are used to compute atom and bond weights, again with the carbon ato m as standard. The new definition of the atom and bond parameters lead s to a periodic variation versus the atomic number Z, with a more natu ral variation when compared with the parameters defined only by Z. The two approaches are used to define and compute topological indices bas ed on graph distance. A quantitative structure-property relationship s tudy is reported for boiling points of 185 acyclic compounds with one or two oxygen or sulfur atoms (devoid of hydrogen bonding), in terms o f four or five molecular descriptors.