A density functional investigation on the structural and electronic properties of niobium–silsesquioxane and niobium-2,2′-thiobisphenolic frameworks as models of an oxo surface

A density functional investigation on niobium±oxo complexes, as models of an oxo surface, is reported. The structural and electronic properties of niobium-silsesquioxanes, considered as possible models for silica-supported transition-metal catalysts, and niobium-2,2'-thiobisphenolic frameworks are compared. The latter is proposed as model for providing insight into the chemistry of carbon-supported transition-metal catalysts. The main difference between them is that the 2,2' -thiobisphenolic framework is structurally less flexible with respect to the Si-O-Si one when coordinating additional ligands.