Flat crown ethers with planar tetracoordinate carbon atoms

Abstract

Novel flat crown ether molecules have been characterized in silico using DFT hybrid and hybrid-meta functionals. Monomer units of Si2C3 with a planar tetracoordinate carbon atom have been used as building blocks. Alkali (Li+, Na+, K+, Rb+, and Cs+) and alkaline-earth (Ca2+, Sr2+, and Ba2+) metals, and uranyl (UO2+ 2) ion selective complexes have also been theoretically identified. The high symmetry and higher structural rigidity of the host molecules may likely to impart higher selectivity in chelation. Theoretical binding energies have been computed and experimental studies are invited. File list (2) download file view on ChemRxiv fce.pdf (39.20 MiB) download file view on ChemRxiv si-flat-crown-ether.pdf (5.79 MiB)

Organomagnesium Crown Ethers and Their Binding Affinities with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ Ions – A Theoretical Study

“…We have seen Be 2 + making such a twisting arrangement with flat crown ether molecules. [60] It is also noted here that Be atom making tetrahedral tetracoordination is quite usual and reported elsewhere in the literature. [61][62][63] For Na + and K + À MgC 6 À 12C4 (high), we could find only two stationary points instead of three as keeping these ions on the side leads to the second most stable isomer.…”

CSiGaAl2−/0andCGeGaAl2−/0having planar tetracoordinate carbon atoms in their global minimum energy structures

“…The molecules containing planar tetracoordinate carbon (ptC) deviate from the usual idea of tetrahedral tetracoordinate carbon as in methane. Nowadays ptC molecules are of great interest for the experimentalists, 1–7 as well as theoreticians 8–15 . The first idea of ptC was given by Monkhorst in 1968, 16 after almost a century of the tetrahedral tetracoordinate carbon concept given by van't Hoff and Le Bel 17,18 .…”

“…In 1976 Schleyer and co‐workers designed the first example of ptC in 1,1‐dilithiocyclopropane and 3,3‐dilithiocyclopropene molecules which showed global minimum structures 9 . After this in silico study, various theoretical studies on ptC skeletons were reported from several research groups 12,25–34 . In 1991, an in silico study by Schleyer and Boldyrev showed that the CAl 2 Si 2 system has a planar structure with the tetracoordinate carbon atom in the middle of the ligand ring and have lower energies than the corresponding tetrahedral isomer 35 .…”

CAl4Mg0/−: Global Minima with a Planar Tetracoordinate Carbon Atom

“…The concept of planar tetracoordinate carbon (ptC) or carbon group elements enthrals both experimentalists [1][2][3][4][5][6][7][8][9][10] and theoreticians [11][12][13][14][15][16][17][18][19] as it is a fundamental deviation from the conventional ideas of tetrahedral tetracoordinate carbon [20,21]. The latter was defined independently by van't Hoff and Le Bel in 1874.…”