Donor Stabilized Diatomic Gr.14 E₂(E = C–Pb) Molecule D–E₂–D (D = NHC,aNHC,^NNHC, NHSi, NHGe, cAAC, cAASi, cAAGe): A Theoretical Insight

Abstract

Quantum chemical calculations have been carried out to explore the detailed electronic structure and bonding scenario in various bis-donor stabilized E2 compounds (E = C–Pb). Our computational findings reveal that the thermodynamic stabilities of the E2 core gradually decrease as we move down the group. A linear D–E–E′–D framework is observed for C2 systems, while the heavier group 14 analogues possess trans-bent geometries. Consideration of few compounds as viable targets for synthesis is suggested by their corresponding calculated formation energies. In addition, the thermodynamic stabilities of C2 systems notably increase with the saturation of the donor ring framework and are even more pronounced for boron-substituted saturated NHD ligand. QTAIM calculations affirmed that the covalent nature of E–E′ bonds shifts toward the donor–acceptor region as one traverses from top to bottom along group 14. The E–D and E′–D bonds in the C2 systems have covalent nature, whereas those in Si2–Pb2 systems are characterized by donor–acceptor bonds. In addition, we have computed proton affinities and vertical ionization potentials (VIPs) of these compounds. An excellent correlation was obtained between calculated VIPs and orbital energies of HOMOs. Furthermore, in the present study, we also explored the effect of bis-donors in the stabilization of heterodiatomic SiC compounds. Our calculations indicate that a typical bonding description of the SiC­(D)2 compounds should be represented by a combination of a classical double bond between C–D with significant donor–acceptor interaction in Si–D, i.e., D → SiCD. The SiC­(D)2 systems are found to be less stable than the corresponding dicarbon compounds C2(D)2, but they show significant stabilization compared to the corresponding disilicon systems Si2(D)2.

Computational Exploration of Mechanistic Avenues in Metal‐Free CO2 Reduction to CO by Disilyne Bisphosphine Adduct and Phosphonium Silaylide

“…Meanwhile, both the silicon atoms utilize sp 3 hybrid orbitals with appreciable p‐mixing (sp 3.94 ) for the formation of Si1−Si2 bond and the corresponding σ ‐bonded electron density is equally shared between the bonding partners. The Si1−Si2 bond exhibits partial double bond character, as evidenced by the corresponding WBI value of 1.269 [54] . The multiple bond character in the Si1−Si2 bond can be elucidated by the second‐order perturbation theory analysis which unfolds 2 e stabilization of 36.6 kcal mol −1 owing to the delocalization of the Si lone pair to the formally empty 3p π orbital of adjacent Si.…”

Amidinate based indium(iii) monohalides and β-diketiminate stabilized In(ii)–In(ii) bond: synthesis, crystal structure, and computational study

“…Interestingly, though the covalent In-X bonds show slightly higher electron densities at the (3, −1) bond critical points (BCPs) in the range of 0.051-0.090 e Å −3 , the positive Laplacian [∇ 2 ρ(r)] values at BCPs account for its highly polarized nature (Table S10, ESI †). 36,37…”

History and Future of Dative Bonds

“…[99,102] The "pro-DB" dicarbon cumulene is unstable with common NHCs, but it wasi solated with cAAC (cyclic (alkyl)(amino)carbene), ab etter p acceptor. [103][104][105][106] Another exemplar (in this case with phosphines) that appeared in 2006w as the carbodiphosphorane, [107] ac arbone, that is as ingle carbon atom whose octet is fulfilled by two DBs (Scheme 17 C). The molecule itself was knowns ince 1961, [108] but apparently 45 years had to pass to comprehend its bondingp attern.T he bent geometry is, again, ap roof of the marginal double bond character,a nd of the capacity of dative bonds to create strong interactions.…”

“…Interestingly, the computed same structure but with carbons instead of silicons was found to be a linear cumulene (i.e., NHC=C=C=NHC in contrast to NHC→Si=Si←NHC), but when coming in contact with a Lewis acid such as BH 3 , the internal carbons swiftly turn to the Si style DB bent geometry (Scheme B) . The “pro‐DB” dicarbon cumulene is unstable with common NHCs, but it was isolated with cAAC (cyclic (alkyl)(amino)carbene), a better π acceptor …”