Planar tetracoordinate carbons with a double bond in CAl₃E clusters

Abstract

The potential energy surfaces of a series of clusters with the formula CAl3E (E = P, As, Sb, Bi) are systematically explored using density functional theory and high level ab initio calculations. The global minimum structure of these clusters contains a planar tetracoordinate carbon atom. The presence of a C=E double bond is supported by the Wiberg bond indices, the adaptive natural density partitioning analysis, and the magnetic response. Our results show that these planar tetracoordinate carbon clusters are both thermodynamically and kinetically viable species in the gas phase.

Planar Tetracoordinate Carbons in Allene-Type Structures

“…1). 34 This strategy has been successfully applied for designing global minima structures with a ptC like CAl3E (E = P, As, Sb, and Bi), 35 CLi3E (E = As, Sb, and Bi), CLi3E + (E = Group 16 element), 36 and C2Al4. 37 Also, it was recently exploiting for predicting planar pentacoordinate silicon and germanium atoms.…”

Structure and Bonding in CE5− (E=Al–Tl) Clusters: Planar Tetracoordinate Carbon versus Pentacoordinate Carbon

“…If a lithium cation interacts with the CE 4 2− fragment, it can be linked to a couple of E atoms (Figure ) to form a planar structure (E=Al and Ga), or directly to the carbon atom to yield a pentacoordinate carbon with a square‐pyramidal geometry (E=In, Tl). Notably, all of the previous clusters, both CE 4 2− and CE 4 Li − , have 18‐valence electrons . This building rule has been exploited to propose, on paper, several planar hypercoordinate carbon atoms, such as CAl 5 + , which is the first cluster in which the global minimum structure possesses a planar pentacoordinate carbon atom .…”

“…Notably,a ll of the previous clusters, both CE 4 2À andC E 4 Li À ,h ave 18-valence electrons. [24][25][26][27][28][29] This building rule has been exploited to propose, on paper, severalp lanar hypercoordinate carbon atoms, such as CAl 5 + , [30] which is the first cluster in which the global minimum structure possesses ap lanarp entacoordinate carbon atom. [10] In contrast, the carbon atom in CAl 5 ,w ith 19-valence electrons,a dopts at etrahedral environment.…”

CLiAl2E and CLi2AlE (E = P, As, Sb, Bi): Planar Tetracoordinate Carbon Clusters with 16 and 14 Valence Electrons

“…Based on CSi 2 Al 2 , CSi 2 Ga 2 , and CGe 2 Al 2 , Schleyer, Boldyrev, and Simons proposed that the presence of 18 valence electrons (ve) is crucial for favoring ptC over corresponding tetrahedral structures. 13,14 As an important rule not a law, 18ve counting is a nice building way to suggest the new ptC/ppC species, both in computational designs and gas-phase experimental works, as exemplified by a series of CAl 4 2– , 10−16 CAl 5 + , 17−21 and CBe 5 4−25 based clusters. As proposed by Keese, 6 the electron counting rule for planar hypercoordinate carbons may depend strongly on the chemical surrounding.…”