Caged Chalcogens: Theoretical Studies on a Tetracoordinated Oxonium Dication and Its Higher Homologues

Abstract

Tetravalent chalcogenium ions utilizing a hydrocarbon cage have been investigated by theoretical means with respect to their geometries and their electronic structure using DFT as well as MP2 calculations. In all cases-even for oxygen-we predict thermodynamically stable molecular entities with chalcogens coordinated by four carbon atoms.

The R3O+···H+ Hydrogen Bond: Toward a Tetracoordinate Oxadionium(2+) Ion

“…Although considerable speculation has been made regarding the potential for oxygen to enter into a fourth covalent bonding relationship, to date tetracoordinate oxygen species have only been implicated as reactive intermediates, 11 or visited in theory. 12,13 Thus, Olah and coworkers produced indirect evidence for the intermediacy of H 4 O 2+ in superacid-activated H + /D + exchange reactions of the hydronium ion, 14 and likewise for R 3 OH 2+ in the alkylation of aromatics with R 3 O + salts.…”

The Quest for Tetracoordinated Halonium Ions: A Theoretical Investigation

“…Recently, we elucidated in a theoretical study the possibility to utilize the remaining lone pair of a trivalent oxonium ion 2 for further binding to a carbocation to afford a tetracoordinated oxonium dication 3 (Scheme ) . Appropriately designed hydrocarbon cages led to the conclusion that a tetracoordination of oxygen should be accessible.…”

Chemistry of the Heterotriquinanes and Heterotriquinacenes

“…We noted an interesting theoretical study by Schneider and Werz on the stabilization of tetracationic chalcogens within polyquinane structures like 66 (Figure 20). 47 While a precursor to 66 can be seen as synthetically challenging to say the least, the corresponding pentacycle 67 could possibly be derived from protonation of 69, which can be made by olefin metathesis of 68, itself amenable to synthesis using the general method described in Scheme 12.…”