Nature and role of formal charge of the ion inclusion in hexanuclear Platinum(II) Host-Guest Species. Insights from relativistic DFT calculations

Abstract

The favorable formation of [Pt6(SR)12 ⊃ Ag]+ host–guest species exhibits the ability of the [Pt6(SR)12] host to incorporate metallic ions at the inner cavity, offering an interesting template for further evaluation of the ion-inclusion nature. Our results show a sizable interaction of −129.1 kcal·mol−1 between Ag(I) and [Pt6(SR)12], of mainly charge-transfer (covalent) character, followed by a contribution from its electrostatic character, and to a small extent from London dispersion type interactions, larger than evaluated for organic hosts. The proposed Cu(I) and Au(I) species exhibit enhanced interaction energy, suggesting the plausible formation of host–guest pairs along with the coinage metal group.Furthermore, the role of the metallic ion charge shows that a more positive formal charge of the ion (Zn(II), Cd(II), and Hg(II)), leads to a sizable stabilization, owing to the increase of the charge-transfer (covalent) character of the interaction, In contrast, for neutral species (Ni, Pd, Pt), a sizable decrease of such character is calculated, denoting that the formal charge of the ion is a relevant factor in determining the stabilization of the host–guest interaction, suggesting to the inclusion of relevant metals ions from different groups, leading to particular optical absorption patterns.