Planar Hexacoordinate Carbons: Half Covalent, Half Ionic

Abstract

The global minima of thirteen combinations of atoms with formula CE 3 M 3 + (E=S-Te and M=Li-Cs) adopt a planar structure with carbon covalently bonded to three chalcogens and ionically bonded to the three alkali-metals to stabilize the first global minima structures containing planar hexacoordinate carbon atoms. File list (2) download file view on ChemRxiv planar_hexacoordinate_carbon.pdf (854.66 KiB) download file view on ChemRxiv Planar_hexacoordinate_carbon_SI.pdf (5.42 MiB)

The inversion of tetrahedral p-block element compounds: general trends and the relation to the second-order Jahn–Teller effect

“…[6][7][8][9] Accordingly, tremendous progress has been made in the eld of planar tetra-, penta-and hexacoordinate carbon during the past decades. [10][11][12][13][14] For the remaining p-block tetrahedrons, the inversion process is much less understood. For hydrides of less electronegative central elements (AlH 4 À , SiH 4 , PH 4 + ), inversion transition states of D 4h symmetry were suggested.…”

Planar Tetracoordinate Carbons in Allene-Type Structures

“…According to the magnetic response, the bent allene-type ECE fragment presents σ-delocalization, which plays an important role in stabilizing the cluster. The chemical bonding analysis revealed a mostly covalent C–E and an electrostatic C–M nature for these ptCs …”

“…The chemical bonding analysis revealed a mostly covalent C−E and an electrostatic C−M nature for these ptCs. 39…”

Analysis of Local and Global Aromaticity in Si3C5 and Si4C8 Clusters. Aromatic Species Containing Planar Tetracoordinate Carbon

“…More recently, "planar hypercoordinate" chemistry expanded to include planar species where the central atom is not limited to carbon, and the coordination number is more than four. Species with planar pentacoordinate [31][32][33][34][35][36][37][38] and hexacoordinate [39][40][41][42] carbons (ppCs or phCs) have been designed in silico. Electronic delocalization (i.e., aromaticity, resonance) plays a determining role in the stability of many of these species.…”