Theoretical Investigation of Promising Molecules for Obtaining Complexes with Planar Tetracoordinate Carbon

Abstract

We have theoretically investigated the stability, chemical bonding, and coordination ability of the 2-Me-2-borabicyclo[1.1.0]but-1(3)-ene (2-Me-2BB) molecule using density functional theory and ab initio molecular dynamics (AIMD) simulations. Calculated results indicated that 2-Me-2BB is both thermodynamically and kinetically stable. The C=C bonds in 2-Me-2BB contain a π bond and a charge shift (CS) bond, different from those in 1-Me-borirene and cyclopropylene. Moreover, 2-Me-2BB can be a σ donor, leading to the formation of TM(2-Me-2BB)L n complexes containing planar tetracoordinate carbon (ptC) with transition metals (TM = Sc–Cu), in which the lone electron pair of 2-Me-2BB results from its ionic resonance form. The lengths and Wiberg bond indices of the TM-ptC bond in TM(2-Me-2BB)L n (TM = Sc–Cu) reveal that 2-Me-2BB can be a ligand similar to N-heterocyclic carbene. Therefore, 2-Me-2BB and its derivatives are promising molecules to obtain complexes with ptC. The natural charges on TM atoms in TM(2-Me-2BB)L n (TM = Sc–Cu) complexes range from −0.97 to 1.54e, indicating that such complexes with ptC might have potential applications in catalytic chemistry.

(Si and B)-heterocyclic carbenes and theoretical design of new molecules

“…For example, the energies of A1 and A5 are lower than those of A1 – 1 and A5 – 1 by 30.2 and 49.0 kcal mol −1 , respectively. Thus, in contrast to BHCs, 35 SiBHCs are more stable compared with their linear isomers. In other words, the substitution of SiX 2 for the CX 2 unit in BHCs prefers to form SiBHCs.…”

“…2, the HOMOs of Ai are mainly the linear combination of the AOs of the two carbon atoms in the C–C bond, which is consistent with those of BHCs. 35,37 According to the π orbital and HOMO, it can be concluded that the C–C bond contains both π and CS bonds analogous to the inverted C–C bond in BHCs. 35 Fig.…”

“…35,37 According to the π orbital and HOMO, it can be concluded that the C–C bond contains both π and CS bonds analogous to the inverted C–C bond in BHCs. 35 Fig. 2S shows an occupied π orbital extending over both carbon atoms and the boron atom, i.e.…”

“…[28][29][30][31] Moreover, we found that BHCs can act as ligands and Lewis bases to form complexes with ptC. 27,[32][33][34][35][36] BHCs can also participate in the Diels-Alder reaction as dienophiles to generate novel [1.1.1]propellanes containing boron atoms. 37,38 Additionally, BHCs were recently used to design porous organic molecules (POMs) 39 and stabilize planar tetracoordinate silicon (ptSi).…”

Elusive Magnetic Compounds Originated from Planar Tetracoordinate Silicon, a Theoretical Prediction

“…Planar tetracoordinate carbon (ptC) has been attracting considerable interest since the ptC concept was first proposed by Hoffman in 1970 . Plenty of compounds with ptC were obtained both experimentally and theoretically, − indicating that such compounds with ptC were the new number of the family of carbon. Because silicon and carbon are situated in the same group in the periodic table, planar tetracoordinate silicon (ptSi) was also paid attention by experimental and theoretical researchers.…”