The Role of Inverted Ligand Field in the Electronic Structure and Reactivity of Octahedral Formal Platinum (IV) Complexes

Platinum complexes are ubiquitous in chemistry and largely used as catalysts or as precursors in drug chemistry, thus a deep knowledge of their electronic properties may help in planning new synthetic strategies or exploring new potential applications. Herein, the electronic structure of many octahedral platinum “IV” complexes is drastically revised especially when the metal is associated with electronegative elements such as halogens and chalcogens. The investigation revealed that in most of the cases the five d platinum orbitals are invariably full, thus the empty antibonding orbitals, usually localized on the metal, are mainly centered on the ligands, suggesting a questionable assignment of oxidation state IV. The analysis supports the occurrence of the Inverted Ligand Field theory in all cases with the only exceptions of the Pt-F and Pt-O bonding. The trends for the molecular complexes are mirrored also by the Density of States plots of extended structures featuring octahedral platinum moieties in association with chalcogens atoms. Based on the gathered information on the electronic structure of complexes and materials, the oxidative addition of a Se-Cl linkage to a square platinum complex to achieve an octahedral moiety has been revised in the framework of the Inverted Ligand Field.