Nearest neighboring code and hydrogen bond index in labeled hydrogen-filled graph and graph of atomic orbitals: application to model of normal boiling points of haloalkanes

Abstract

Nearest Neighboring Code (NNC) of given vertex in molecular graph is a topological and chemical invariant. Numerical value of the NNC k of given kth vertex is mathematical function of both number and composition of vertices which are neighbors of the kth vertex in molecular graph. Hydrogen Bond Index (HBI) is global invariant of a molecular graph. Descriptors calculated with optimal correlation weights of the NNC and HBI have been studied. The optimal correlation weights have been obtained by Monte Carlo method. This approach is named as Optimization of Correlation Weights of Local and Global graph Invariants (OCWLI). Two categories of molecular graph have been used. First category is a Labeled Hydrogen-Filled Graphs (LHFGs). Second category is a Graph of atomic orbitals (GAO). Types of vertices in the LHFG are chemical elements (i.e. H, C, F, and Cl). Types of vertices in the GAO are atomic orbitals (i.e. 1s 1, 1s 2, 2s 2, 2p 2, 2p 5, 2p 6, 3s 2, and 3p 5). Comparison of series of models based on extended connectivity, NNC, and HBI in the LHFG and GAO has shown, that best OCWLI model is one based on optimized correlation weights NNC and HBI in the GAO. Statistical characteristics of this model are the following: n=138; r 2=0.9897; s=7.87 (°C); F=13094 (Training Set), n=138; r 2=0.9871; s=6.94 (°C); F=10374 (Test Set), n=276; r 2=0.9886; s=7.41 (°C); F=23863 (all compounds)