Can cation-π and cation-lone pair interaction stabilize alkali/alkaline earth metal ion-furan adducts? Acumen from...

The interaction of main group metal ions [(M(I/II)] specifically Li(I), Na(I), K(I), Be(II), Mg(II) and Ca(II) ions with Furan (Fur) are studied through its exposed π-surface and lone pair of O-atom (LP O) using density functional theory (DFT). The interaction via both the considered modes is strong enough to stabilize 1:1 [M(I/II):Fur] and 1:2 [M(I/II):2Fur] type adducts. Formation of cation-π (12.13 to 291.02 kcalmol^-1) adducts are more favourable than cation-lone pair (11.80 to 284.40 kcalmol^-1) adducts. The interactions are thermodynamically favourable, and enthalpy and free energy driven. Presence of solvent phase resulted remarkable weakening of the adducts; strength of the interaction is inversely related to the solvent dielectrics. There exist a moderately strong relationship and a strong linear relationship between stability and second order perturbation energy [E(2)] of primary donor-acceptor interaction, and stability and electron density of the adducts, respectively. SAPT0 calculations determined nature of the interactions depending on the positions of interacting species, suggesting considerable contribution of covalent component in stabilizing Be(II) adducts. QTAIM and NCI analyses also performed to validate the major role on ionic interaction in stabilizing the other adducts.