Theoretical foundation of molecular structures useful in structure/property relationships

Molecular-orbital methods are used to provide the geometric structures and electron distributions, to improve understanding of the chemical behaviour of molecular systems. Semi-empirical algorithms, based on modified (or complete) neglect of differential overlap (MNDO and CNDO/Fischer-Kollmar) methods were applied for investigating structures and infrared spectroscopic properties of formamide, oxirene, and olefin π-complexes of nickel. By considering alternative structures (isomers), it is possible to recognize the relationships between spatial structures and their dynamics (e.g., molecular vibrations), but structure and dynamics cannot be fully separated.