Abstract

In conceptual density functional theory (CDFT), physical and mathematical concepts used in the DFT area are repurposed and combined to form descriptors to elucidate chemical concepts, especially the concepts related to reactivity. Summarizing what has been said about the CDFT and extrapolating to the future, its aim can be defined as “to develop nonempirical, mathematically and physically sound, density-based, quantum-mechanical theory for interpreting and predicting chemical phenomena, specially chemical reactions” [1]. The conceptual DFT is based on three fundamental concepts: observability, universality, and mathematical rigor. Taking into account different spin states is an extremely important aspect of computational studies of transition metal complexes and some other systems. Despite its significant computational demands, spin CDFT should be thoroughly explored as well, especially for such phenomena as transition metal catalysis, radical reactions, and singlet–triplet gaps in low-valent main-group chemistry. In general, CDFT is considered as a very important, versatile, and extremely useful tool in studying reactivity properties of various chemical compounds, including complexes/compounds of different metals. Due to the quite numerous publications in this area, we will review only some more interesting and appealing examples of the CDFT applications in studies of various metal compounds/complexes, first giving attention to several more general works and then considering some more specific examples.