The substitution effect on heavy versions of cyclobutadiene

Abstract

ABSTRACT:The structural and electronic characteristics of the M 4 R 4 with M ϭ C, Si, Ge and R ϭ H, F, Cl, OH, MgH, BH 2 , NH 2 Li are studied by ab initio calculations based on density functional theory using the hybrid B3LYP functional and 6-311ϩϩG* basis set. The results of natural bond orbital analysis (NBO), the analysis of structural parameters (bond lengths and bond angle, dihedral angle), atoms in molecules based theory (AIM) topological parameters such as the characteristics of bond critical points (electron densities and their Laplacians) leads to the conclusion that interamolecular interaction due with OH, MgH 2 , and NH 2 substitutions are different from other derivatives. The cyclobutadiene ring and its heavy versions display very different geometrical structures. The cations and anions of C 4 R 4 , Si 4 R 4 , and Ge 4 R 4 were studied to determine the effect of substitution on structure and stability. It has been shown that substitutions with ability of forming hydrogen bonds, bound to the silicon and germanium atoms are able to change the properties of the four-member rings more than the other substitutions. Comprehensive analyses of calculated NICS (nucleusindependent chemical shifts), polarizability, electrophilicity, and electron density are done.

AIM and NBO analyses on hydrogen bonds formation in sugar-based surfactants (α/β-d-mannose and n-octyl-α/β-d-mannopyranoside): a density functional theory study

“…Therefore, these bonds are classified as medium hydrogen bond and partially covalent-partially electrostatic (Pc-Pe). [58] The electron density for α-D-Man and C 8 O-α-D-Man …”

Tetragermacyclobutadiene: Energetically Disfavored with Respect to Its Structural Isomers

“…Computational work on Ge 4 H 4 in the literature is scarce, but two recent works deserve notice here. First, Nazari and Doroodi studied substituent effects on the cyclic isomers of C 4 R 4 , Si 4 R 4 , and Ge 4 R 4 , with R including H, F, Cl, OH, MgH, BH 2 , NH 2 , and Li 32. Whilst this work is important in considering possible new synthetic strategies, we do not consider it further herein because it is outside the scope of this study.…”

“…The broad scope of the Frenking study highlights similarities and differences between Group 13 and Group 14 E 4 H 4 isomers. Also, Nazari and Dorrodi examined substitution effects for E 4 R 4 (E=C–Ge) by using B3LYP with the 6‐311++G* basis set 32. Whereas these reports have included computations on the Ge 4 H 4 system, among many others, no high‐level theoretical study has been devoted entirely to tetragermacyclobutadiene and its related structural isomers.…”

SOLVENT INFLUENCE ON THE STABILITY AND PROPERTIES OF Si4H4 ISOMERS BY COMPUTATIONAL METHODS

“…Numerous unusual tetrasilacyclobutadiene or tetragermacyclobutadiene analogues together with a planar-rhombic or puckered Si 4 ring [1,2], a rather folded Ge 4 ring [3], or a puckered Si 3 Ge ring with ylide structure [4] were reported. Theoretical studies of the simplest member of the Si 4 R 4 family (Si 4 H 4 ) were explored a puckered Si 4 ring with D 2d symmetry for this molecule [5,6]. The central silicon skeleton from the simplest Si 4 H 4 to the complex Si 4 (EMind) 4 (EMind = 1,1,7,7-tetraethyl-3,3,5,5-tetramethyl-shydrindacen-4-yl) compound contains various low-symmetry configuration deviations of the reference square-planar geometry.…”