Interaction of Silver Clusters with Cholesterol Ligands

The structures of small silver clusters (Ag2, Ag3, Ag13) and their interaction with ligands of the cholesterol series, namely, cholesterol (Ch) and thiocholesterol (TCh), are calculated by the density functional theory (DFT) methods and the second-order Møller–Plesset perturbation theory (MP2). Trends in the geometric structure and interaction energy of the silver–cholesterol ligand cluster are estimated depending on the size of the metal cluster and the replacement of cholesterol by the sulfur-containing analogue. For Ch–Ag13 and TCh–Ag13 systems, the geometric structure of the metallic subsystem is a slightly distorted icosahedron with the Ag–Ag bond length ranged 2.8–3.0 Å. Cholesterol is coordinated to the icosahedral facet so that the shortest Ag–O distances range from 2.3 to 2.4 Å. In the case of thiocholesterol, a configuration in which the ligand is coordinated by the edge of the icosahedron with two approximately equal distances of Ag–S (2.537 and 2.547 Å) is preferable.