DFT Modeling of Polyethylene Chains Cross-linked by Selected ns1 and ns2 Metal Atoms

. 2024 Sep 12 ; 128 (36) : 7634-7647. [epub] 20240902

Status PubMed-not-MEDLINE Jazyk angličtina Země Spojené státy americké Médium print-electronic

Typ dokumentu časopisecké články

Perzistentní odkaz   https://www.medvik.cz/link/pmid39219502

We analyze the structures, stabilities, and thermochemical properties of polyethylene (PE) oligomer chains cross-linked by metal (M) atoms through C-M-C bonds. Representative PEn-Mm-PEn complexes contain between 7 and 15 carbon atoms in each oligomer and one to three Li, Be, Mg, Zn, Ag, or Au cross-linking metal elements. PEn-Mm-PEn complexes are quasiplanar with nearly parallel PE chains. Their stability is determined by covalent C-M-C bonds accompanied by noncovalent dispersion interactions between PEn chains. Using the CAM-B3LYP+D3BJ+ABC functional, the binding energies of PE15-M-PE15 with respect to two PE15 radicals and metal fragments are -225, -230, -322, -551, -289, and -303 kJ/mol for Li, Ag, Au, Be, Mg, and Zn atoms, respectively. Entropy contributions (109 to 121 kJ/mol at 298.15 K) destabilize all complexes significantly. With two cross-linking metal elements in PE15-M2-PE15 complexes, binding energies are about double. Complexes with several open-shell Li, Ag, or Au doublet atoms have spins located on separated C-M-C bonds. High-spin PE15-Mm1-PE15-Mm2-PE15 complexes of three PE oligomers cross-linked by up to five doublet metal atoms create parallel PE tubes, which are suggested as elementary cells for modeling magnetic polymer tubes.

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Slater-Condon Rules and Spin-Orbit Couplings: 2‑(2-(2,5-Dimethoxybenzylidene)hydrazineyl)-4-(trifluoromethyl)thiazole a Test Case

. 2025 Dec 02 ; 10 (47) : 57776-57789. [epub] 20251119

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