Journal of Structural Chemistry最新文献

Reduction of Ar^BIG-bian (Ar^BIG-bian = 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene) by an excess of metal aluminum in the presence of AlCl₃, AlBr₃ or AlI₃ in toluene leads to the formation of dihalide anion-radical complexes [(Ar^BIG-bian)^–AlX₂] (X = Cl (1), Br (2), I (3)). The newly obtained compounds 1, 2, 3 are isolated in the crystal state and characterized by IR and EPR spectroscopies and by elemental analysis. Molecular structures of the complexes are determined by XRD.

Information on the synthesis and structure of lanthanide coordination compounds with ligands containing a benzothiazolate fragment in their structure is summarized up to the beginning of 2024. Particular attention is paid to the photo- and electroluminescent properties of these compounds.

A new coordination compound of Co(II) [Co(pydc)₂](pydcH₂)(Hapy)(H₂O)₅ (1) (where, pydcH₂ = pyridine-2,6-dicarboxylic acid; Hapy = protonated 2- aminopyridine) was synthesized and characterized by single crystal X-ray diffraction (SC-XRD) analyses. Crystallographic analysis (CIF file CCDC no. 2236169) revealed that complex 1 has distorted octahedral geometry with pydc coordinated as a tridentate ligand to a metal ion. The electronic structure of the complex was determined using DFT calculations with pseudo potential of LANL2DZ basis function for Cobalt atom while B3LYP/GEN level using 6-31+G* basis set for other atoms. The optimized structure can reproduce the crystal structure with good accuracy at this computational level. Frontier molecular orbital analysis and molecular electrostatic potential (MEP) have been evaluated to understand the reactivity characteristics of the complex. Natural bond orbital analysis illustrates the charge transfer between the donor and acceptor sites of the investigated complex. Further, the intermolecular contacts of the complex areanalyzed through Hirshfeld surface analysis and finger print plots.

A dichlorophenyl substituted nitronyl nitroxide radical 2-(2,6-dichlorophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (L) is prepared, its structure and magnetic properties are studied. It is shown that the interaction of bis(hexafluoroacetylacetonato)copper(II) [Cu(hfac)₂] with L leads to the formation of the {[Cu(hfac)₂][Cu(hfac)₂L₂]} heterospin complex whose crystal structure consists of pseudo-polymer chains formed by alternating single-spin [Cu(hfac)₂] and three-spin [Cu(hfac)₂L₂] fragments. It is established that the temperature dependence of magnetic susceptibility of {[Cu(hfac)₂][Cu(hfac)₂L₂]} is determined by ferromagnetic exchange interactions between unpaired electrons of Cu(II) ions and the axially coordinated L in three-spin fragments.

Molecular and electronic structures of heterobimetallic Ln(III)–Cu(II) C₅-symmetric metallamacrocycles (15-metallacrowns-5) bearing L-α-alaninehydroximate (Alaha) ligands are studied by density functional theory (DFT). Full structural DFT optimizations are performed for complexes of the composition {Ln(H₂O)₄[15-MC_Cu(II)Alaha-5]}³⁺ (Ln = La, Ce, Pr) in high- and low-spin states using the PBE functional in the scalar-relativistic approximation. The spin states modeled are: sextet, quartet, and doublet for the La(III)–Cu(II) complex; septet, quintet, triplet, and open-shell singlet for the Ce(III)–Cu(II) complex; octet, sextet, quartet, and doublet for the Pr(III)–Cu(II) complex. The involvement of all unpaired electrons in antiferromagnetic interactions substantially decreases the Gibbs free energy of the singlet Ce(III)–Cu(II) complex compared to that of the doublet La(III)–Cu(II) and Pr(III)–Cu(II) derivatives: –4.4 kcal/mol, –2.0 kcal/mol, and –2.2 kcal/mol respectively (at 5 K). Spin density distributions, electron localization functions (ELFs), and the Laplacian of the electron density in 15-MC-5 reveal O_h and D_6h types of the f electron density symmetry around the Ce and Pr nuclei respectively. The effect of the 15-MC-5 metallamacrocyclic environment on the outer electron shell of the central diamagnetic ion is exemplified by the La(III)–Cu(II) complex. The topological parameters of the electron density are calculated at (3, –1) bond critical points for metal–ligand interactions using the quantum theory of atoms in molecules (QTAIM).

We present a study of the structural features of polycrystalline a diamond film (PCDF) synthesized by the microwave plasma-enhanced chemical vapor deposition method from a hydrogen/pentane mixture and consider its photoelectric response to synchrotron radiation. Raman spectroscopy analysis of the PCDF cross-section revealed the presence of sp²-hybridized inclusions. As the distance from the PCDF growth surface increases, the amount of the non-diamond phase also increases, while its morphology changes from amorphous to crystalline graphite-like carbon. The investigation of the photoelectric response of PCDF was carried out at the “Cosmos” station using synchrotron radiation from the VEPP-4M storage ring. The PCDF detector exhibited maximum sensitivity at low bias voltage. This effect was attributed to the increased efficiency of collecting photo-induced charge carriers from the diamond to the sp²-hybridized inclusions followed by their subsequent transport through conductive paths along the boundaries between diamond crystallites.

The electronic structure of NoO₂ and the valence-band X-ray photoelectron spectrum (XPS) in the energy range from 0 eV to ~40 eV are calculated by the relativistic discrete variation method. Significant covalency effects are observed in NoO₂, which are due to a considerable overlap of not only No 6d AO but also No 6p and No 5f AOs with oxygen orbitals. The MO histogram and scheme are derived, which enable the comprehension of features of the chemical bond nature and the structure of the XPS spectrum of valence electrons in NoO₂.

Deformcell is a python script designed to simplify and fasten routine procedure of preparing crystal structure files for calculating various mechanical properties in VASP program. The software allows users to prepare POSCAR files for calculations of different mechanical properties performing energy calculations of deformed crystallographic unit cells. It has been specially designed to allow users to automate unit cell deformation prior to energy calculations, making it useful both for scientific research and teaching computational chemistry applied to chemical materials sciences.

Two derivatives of imidazolinones, specifically DMPI {(4Z)-4-(4-(dimethylamino)benzylidene)-2-methyl-1,4-dihydro-5H-imidazolin-5-one} and MMPI {(4Z)-4-(4-methoxybenzylidene)-2-methyl-1-((pyridin-3-yl)methyl)-1,4-dihydro-5H-imidazolin-5-one} are reported which were synthesized under reflux conditions. Both the ligands are characterized with different analytical techniques including NMR spectroscopy, mass spectrometry, IR Spectroscopy. The subsequent elucidation of their solid-state structures was achieved through the single crystal X-ray diffraction method, providing detailed insights into their molecular arrangements. In the crystalline lattice, the asymmetric unit of DMPI comprises a solitary DMPI molecule, whereas MMPI reveals a more intricate arrangement with four molecules within its asymmetric unit. Various types of supramolecular interactions such as C–H⋯O, C–H⋯N, C–H⋯π and π⋯π interactions are observed in the X-ray structures where a trifurcated C–H⋯O bonds are also observed in both the ligands. All these interactions guide the formation of 3D supramolecular architecture in the solid-state of both compounds. Besides these, the 2D fingerprint and Hirshfeld surface analysis computations were served to prove and quantify various supramolecular interactions within the crystal lattice.

N-(2-(diphenylphosphino)ethyl)-4,6,7-trifluoro-2,1,3-benzothiadiazol-5-amine (Ph₂PCH₂CH₂NH-btd-F₃ (PCCN)) is prepared by the reaction of 4,5,6,7-tetrafluoro-2,1,3-benzothiadiazole (btd-F₄) with 2-(diphenylphosphino)ethyl-1-amine (Ph₂PCH₂CH₂NH₂) leading to the nucleophilic substitution of F^– by a phosphinamide fragment (Ph₂PCH₂CH₂NH)^– in btd-F₄. Phase 1 (a product of cocrystallization of PCCN (85%) and its oxide Ph₂P(O)CH₂CH₂NH–btd-F₃ (POCCN, 15%)) is obtained by the separation of the mixture of products by thin-layer chromatography and subsequent evaporation of the solution. POCCN is obtained preparatively using the oxidation of PCCN by hydrogen peroxide. Phase 1, two polymorphs of POCCN (2 and 4), and the POCCN·C₆H₆ solvatomorph (3) are characterized by XRD. The P–C–C–N fragment in these phases adopts either a bent gauche-conformation with an intramolecular N–H⋯O hydrogen bond or an anti-conformation stabilized by a pair of intermolecular hydrogen bonds combining the molecules into a dimer. According to the DFT data, gauche-POCCN has a larger negative electrostatic potential at F and N than anti-POCCN, i.e. the btd-F₃ fragment of the first conformation is more likely to participate in predominantly electrostatic intermolecular interactions.