Spectroscopic and structural studies, thermal characterization, optical proprieties and theoretical investigation of 2-aminobenzimidazolium tetrachlorocobaltate(II)

In this study we present the crystal structure, spectroscopic and thermal behavior, Hirshfeld surface analysis, and DFT calculations of a new organic-inorganic hybrid compound (C₇H₈N₃)₂[CoCl₄]. This compound crystallizes in the centrosymmetric space group P1¯. Single-crystal X-ray diffraction analysis indicates that structure consists of a succession of mixed layers formed by organic cations and inorganic anions parallel to the (001) plane and propagate according to the c-axis. Layers further are assembled into a 3D supramolecular architecture through N-H^…Cl hydrogen bonds and π^…π interactions. The peak positions of the experimental PXRD pattern are in agreement with the simulated ones from the crystal structure, indicating phase purity of the title compound. The presence of the different functional groups and the nature of their vibrations were identified by ATR-FTIR and FT-Raman spectroscopies. The tetrahedral environment of Co²⁺ was confirmed by UV-visible spectroscopy, where the spectrum shows three weak absorption bands in the visible range due to d-d electronic transitions ⁴A₂(F) → ⁴T₂(F), ⁴A₂(F) → ⁴T₁(F) and ⁴A₂(F) → ⁴T₁(P) typical of Co(II) coordination compounds. The direct and indirect optical band gap values were determined by Tauc method. The optimized structure and calculated vibrational frequencies were obtained by density functional theory (DFT) using B3LYP functional. TGA and DSC coupled to mass spectrometry (MS) experiments under argon atmosphere in the temperature range (25-950 °C) were carried out in order to determine the thermal stability of the title compound.

Crystal structure, Hirshfeld surface analysis and physicochemical characterization of bis-[4-(di-methyl-amino)-pyridinium] di-μ-chlorido-bis[di-chlorido-mercurate(II)]

The title mol-ecular salt, (C7H11N2)2[Hg2Cl6], crystallizes with two 4-(di-methyl-amino)-pyridinium cations (A and B) and two half hexa-chlorido-dimercurate(II) anions in the asymmetric unit. The organic cations exhibit essentially the same features with an almost planar pyridyl ring (r.m.s. deviations of 0.0028 and 0.0109 Å), which forms an inclined dihedral angle with the dimethyamino group [3.06 (1) and 1.61 (1)°, respectively]. The di-methyl-amino groups in the two cations are planar, and the C-N bond lengths are shorter than that in 4-(di-methyl-amino)-pyridine. In the crystal, mixed cation-anion layers lying parallel to the (010) plane are formed through N-H⋯Cl hydrogen bonds and adjacent layers are linked by C-H⋯Cl hydrogen bonds, forming a three-dimensional network. The analyses of the calculated Hirshfeld surfaces confirm the relevance of the above inter-molecular inter-actions, but also serve to further differentiate the weaker inter-molecular inter-actions formed by the organic cations and inorganic anions, such as π-π and Cl⋯Cl inter-actions. The powder XRD data confirms the phase purity of the crystalline sample. Furthermore, the vibrational absorption bands were identified by IR spectroscopy and the optical properties were studied by using optical UV-visible absorption spectroscopy.

Crystal structure, Hirshfeld surface analysis and energy framework calculation of the first oxoanion salt containing 1,3-cyclo-hexa-nebis(methyl-ammonium): [3-(aza-niumylmeth-yl)cyclo-hex-yl]methanaminium dinitrate

The title salt, C8H20N22+·2NO3-, was obtained by a reaction between 1,3-cyclohexa-nebis(methyl-amine) and nitric acid. The cyclo-hexane ring of the organic cation is in a chair conformation with the methyl-ammonium substituents in the equatorial positions and the two terminal ammonium groups in a trans conformation. In the crystal, mixed cation-anion layers lying parallel to the (010) plane are formed through N-H⋯O hydrogen-bonding inter-actions; these layers are formed by infinite undulating chains running parallel to the [001] direction. The overall inter-molecular inter-actions involved in the structure were qu-anti-fied and fully described by Hirshfeld surface analysis. In addition, energy-framework calculations were used to analyse and visualize the three-dimensional topology of the crystal packing. The electrostatic energy framework is dominant over the dispersion energy framework.

Crystal structure and Hirshfeld surface analysis of bis-(2,6-di-amino-pyridinium) tetra-chlorido-cobaltate(II)

In the title mol-ecular salt, (C5H8N3)2[CoCl4], the cations are protonated at their pyridine N atoms and the anion is an almost regular tetra-hedron. The crystal structure consists of alternating inorganic layers, built from tetra-chlorido-cobaltate anions, and organic layers formed by protonated cations of 2,6-di-amino-pyridinium. The crystal packing is governed by C/N-H⋯Cl hydrogen-bonding inter-actions between the organic and the inorganic ions and Cl⋯Cl inter-actions. Moreover, the cations show a π-π stacking inter-action [inter-centroid distance = 3.763 (2) Å]. The prevalence of these inter-actions is illustrated by an analysis of the three-dimensional Hirshfeld surface and by two-dimensional fingerprint plots.

Structure cristalline, caractérisation spectroscopique, calcul DFT et analyse de surface Hirshfeld du perchlorate de p-toluidinium

The synthesis of p-toluidinium perchlorate (systematic name: 4-methyl-anilinium perchlorate), C7H10N+·ClO4-, was carried out from an aqueous reaction of perchloric acid with p-toluidine. This compound was characterized by powder XRD, IR and UV-Vis spectroscopy. The structure was further confirmed by a single-crystal X-ray diffraction study. The crystal structure is formed by a succession of two-dimensional mol-ecular layers consisting of perchlorate anions and organic cations parallel to the (100) plane and located at x = 2n + ½ (n ∈ Z). Each mixed layer is formed by infinite chains {C7H10N+·ClO4-} n parallel to the [010] direction and developing along the c axis, generating R24(8), R22(4) and R44(12) graph-set motifs. The results of a theoretical study using the DFT method at the B3LYP/6-311++G(d,p) level are in good agreement with the experimental data. Hirshfeld surface and fingerprint plots reveal that the structure is dominated by O⋯H/H⋯O (54.2%), H⋯H (26.9%) and C-H ⋯π (14.3%) contacts. The studied crystal was refined as a two-component twin.

Structure cristalline et analyses thermique et de surface Hirshfeld du diperchlorate de 4-aza-niumyl-2,2,6,6-tétraméthylpipéridin-1-ium

The synthesis of 4-aza-niumyl-2,2,6,6-tetra-methyl-piperidin-1-ium diperchlorate, C9H22N22+·2ClO4-, was carried out from an aqueous reaction of perchloric acid with 4-amino-2,2,6,6-tetra-methyl-piperidine. This compound was characterized by TGA-DSC analysis and single-crystal X-ray diffraction. The piperidine ring of the dication adopts a chair conformation and the orientation of the C-NH3 bond is equatorial. One of the two crystallographically independent perchlorate anions exhibits disorder [occupancies 0.625 (7) and 0.375 (7)]. The crystal packing is constituted by a succession of mixed layers parallel to the (-102) plane, made up of C9H22N22+ dications and ClO4- anions. These ions are linked by normal and bifurcated N-H⋯O hydrogen bonds with R44(12) graph-set motifs, generating a two-dimensional network. The inter-molecular inter-actions in the crystal structure were qu-anti-fied and analysed using Hirshfeld surface analysis.

Crystal structure of methyl 1-(4-fluorobenzyl)-4-methoxy-5-oxopyrrolidine-3-carboxylate, C14H16FNO4

C14H16FNO4, monoclinic, P21/n (no. 14), a = 10.189(4) Å, b = 7.742(2) Å, c = 17.240(5) Å, β = 94.50(1)°, V = 1355.8(7) Å3, Z = 4, R gt(F) = 0.0420, wR ref(F 2) = 0.1183, T = 295 K.

Crystal structure and Hirshfeld surface analysis of the new cyclo-diphosphazane [EtNP(S)NMe2]2

A new cyclo­diphosphazane, [EtNP(S)NMe₂]₂, was synthesized and characterized by NMR and EDX spectroscopy and single-crystal XRD. The stability of the structure is ensured only by van der Waals inter­actions and the their prevalence is confirmed by an analysis of the three-dimensional Hirshfeld surface (HS) and two-dimensional fingerprint plots (FP).

The cyclic compound 2,4-bis(dimethylamino)-1,3-diethylcyclodiphosphazane-2,4-dithione [systematic name: 2,4-bis(dimethylamino)-1,3-diethyl-1,3,2λ⁵,4λ⁵-diazadiphosphetidine-2,4-dithione], C₈H₂₂N₄P₂S₂ or [EtNP(S)NMe₂]₂, is member of a class of mol­ecules that may be used, by virtue of their complexation properties, for the extraction of metals. This compound was characterized in solution by (¹H and ³¹P) NMR, and in the solid state by energy-dispersive X-ray spectroscopy (EDX) and by X-ray crystallography. In the crystal, the mol­ecule sits on an inversion centre such that the P and N atoms form a centrosymmetric cyclic P₂N₂ arrangement. The crystal packing is dominated by van der Waals inter­actions. The prevalence of these inter­actions is illustrated by an analysis of the three-dimensional Hirshfeld surface (HS) and by two-dimensional fingerprint plots (FP). The relative contribution of different inter­actions to the HS indicates that the H⋯H contacts account for 74.3% of the total HS area.

The influence of P/As substitution in the melilite-like Na2Co(P2-xAsx)O7 (x = 0.40 and 0.93) solid solutions

To investigate the influence of P/As substitution on structures and electrical properties, e.g. the effect on material densities, two new solid P/As-doped solutions, Na₂CoP_1.60As_0.40O₇ (disodium cobalt diphosphorus arsenic heptaoxide) and Na₂CoP_1.07As_0.93O₇ (disodium cobalt phosphorus arsenic heptaoxide), with melilite-like structures have been synthesized by solid-state reactions. Their unit-cell parameters are in agreement with Vegard's law. The obtained structural models were investigated by the bond valence sum (BVS) and charge distribution (CHARDI) validation tools and, for the latter, the structures are described as being built on anion-centred polyhedra. The frameworks can be described as layered and formed by {[Co(P,As)₂O₇]^2-}_∞ slabs, with alkali cations sandwiched between the layers and with the interlayer spaces increased due to P/As substitution. The BVS model was extended to a preliminary simulation of the sodium conduction properties in the studied structural type and suggests that the most probable sodium conduction pathways are bidimensional, at the (002) planes.

Crystal structure of Na4Co7-x Al0.67x (As1-y P y O4)6 (x = 1.60; y = 0.116)

Tetra­sodium hepta­(cobalt/aluminium) hexa­(arsenate/phosphate) is a new member of the isostructural family of compounds with the general formula A₄M₇(XO₄)₆ (A: Na, K; M: Ni, Co; X: P, As). The proposed structural model is based both on a careful investigation of the crystal data, as well as validation tools by means of bond-valence-sum (BVS) and charge-distribution (CHARDI) calculations.

The title compound, tetra­sodium hepta­(cobalt/aluminium) hexa­(arsenate/phosphate), Na₄Co_5.40Al_1.07(As_0.883P_0.116O₄)₆, was prepared by a solid-state reaction. It is a new member of the family of isostructural compounds with the general formula A₄M₇(XO₄)₆ (A: Na, K; M: Ni, Co; X: P, As) that is most similar to Na₄Co_5.63Al_0.91(AsO₄)₆. The Co²⁺ ions in the title compound are substituted by Al³⁺ in a fully occupied octa­hedral site (site symmetry 2/m) and a partially occupied tetra­hedral site (site symmetry 2). A third octa­hedral site is fully occupied by Co²⁺ ions only. With regard to the P and As atoms, one site (site symmetry m) is simultaneously occupied by As and P, whereas in the second site there is only arsenic. The alkali cations are, as in the isostructural compounds, distributed over half-occupied crystallographic sites, with a positional disorder of one of them. The proposed structural model is based both on a careful investigation of the crystal data, as well as validation by means of bond-valence-sum (BVS) and charge-distribution (CHARDI) calculations. The correlation between the X-ray refinement and the validation results is discussed.

4-Aza-niumyl-2,2,6,6-tetra-methyl-piperidin-1-ium dinitrate

In the crystal structure of the title salt, C9H22N2 (2+)·2NO3 (-), the piperidine ring of the dication adopts a chair conformation and the orientation of the C-NH3 bond is equatorial. The ions are linked by normal and bifurcated N-H⋯O hydrogen bonds in R 2 (2)(6), two R 4 (2)(8) and R 3 (4)(14) graf-set motifs, generating a three-dimensional network.

4-ammonio-2,2,6,6-tétraméthylpipéridinium chromate dihydrate

The title compound, 4-ammonio-2,2,6,6-tetramethylpiperidinium chromate dihydrate, (C9H22N2)[CrO4]*2H2O, crystallizes in the monoclinic system with one organic cation and one chromate anion in the asymmetric unit, together with three independent sites for water molecules, two of which have their O atoms located on twofold axes. The structure is composed of layers built up from CrO4(2-) tetrahedra and water molecules alternating with C9H22N2(2+) cations and additional water molecules. Two types of hydrogen bonds, O-H...O and N-H...O, ensure the cohesion and stability of the structure.