Monoclinic Space Group Research Articles

Polyiodides of amino acids. Betainium triiodide

A new salt of betaine, betainium triiodide, (BetH)(I3), was synthesized and characterized using structural analysis and infrared spectroscopy. It crystallizes in the monoclinic space group C2/m with the asymmetric part containing half of the formula unit. The structure determination revealed that the betainium cation forms an (A+···A+) type centrosymmetric betainium···betainium dimeric cation with an O···O distance of 2.662(6) Å. The presence of the triiodide anion in the structure provides semiconductor properties of the resulting crystal. The bandgap for (BetH)(I3) was calculated from the electronic structure based on the crystal structure and measured from the diffuse reflectance spectrum. The results are compared with two previously known structurally characterized salts of amino acids that also contain the triiodide anion: (l-AlaH···l-Ala)(I3) and (GlyH)(I3). Thermal properties of the crystal were studied by TG and DSC methods.

Crystal structure and thermal behavior of three potential high-energy compounds of hydro-closo-borates with guanidinium

The novel guanidinium hydro-closo-borates featuring [BnHn]2– (n = 10 and 12) anions were successfully synthesized via the direct reaction of the corresponding free acids, (H3O)2[BnHn], with guanidinium carbonate, (CN3H6)2[CO3], in aqueous media. The resulting compounds crystallize in different monoclinic space groups such as C2/c, P2/c and P21/n for (CN3H6)2[B10H10], (CN3H6)2[B12H12] ⋅ 2 H2O and Cs(CN3H6)[B12H12], respectively. An intriguing aspect of these crystal structures was the observation of dihydrogen bonding interactions involving the negatively polarized hydrogen atoms of the boron clusters and the positively polarized hydrogen atoms in the guanidinium cations (Bδ+–Hδ–⋅⋅⋅Hδ+–Nδ–). Furthermore, a classical hydrogen bonding system is evident in (CN3H6)2[B12H12] ⋅ 2 H2O. The presence of negatively charged hydrogen (Hδ–) in hydroborate anions and positively charged hydrogen atoms (Hδ+) in guanidinium cations in these structures suggests their potential for facilitating H2 generation upon thermal decomposition. Furthermore, theoretical analysis predicts that under an oxygen atmosphere, diguanidinium dodecahydro-closo-hydroborate has the capacity to yield energy up to 11 MJ/mol.

Crystal structure and photocatalytic activity of luminescent 3D-Supramolecular metal organic framework of dysprosium

A 3D supramolecular metal organic framework of dysprosium has been fabricated through a facile hydrothermal procedure with the ligand, 2,6-naphthalene disulphonic acid and the co-ligand, 4,4′-bipyridine. The MOF has been characterized as [C60H81DyN8O30S4] by routine analytical procedures. SXRD studies of the MOF show the existence of a hydrogen-bonded 3D supramolecular structure with high porosity. It crystallizes in monoclinic space group P21/n with unit cell parameters, a = 16.5424(6) Å, b = 37.0052(14) Å, c = 24.4361(9) Å, β = 100.7410°, α = γ = 90°. The Dy-MOF has eight coordinated water molecules around the metal centre and exhibits square anti-prismatic geometry. The band gap is 3.11 eV. The degradation experiments under visible light confirmed that Dy-MOF can act as a photocatalyst. Addition of hydrogen peroxide remarkably increases the degradation efficiency of the MOF through an advanced oxidation process. The newly synthesized MOF produced sharp emission peaks characteristic of dysprosium ion.

KBi(SeO4)(IO3)Cl: A mixed-anion oxychloride with three types of building units in one structure

A novel mixed-anion oxychloride, KBi(SeO4)(IO3)Cl, has been hydrothermally synthesized and structurally characterized. The compound crystallizes in the monoclinic space group of P21/c with cell parameters of a = 7.8802(2) Å; b = 10.8088(2) Å, c = 10.1364(2) Å, β = 112.849(1)°, V = 795.62(3) Å3, and Z = 4. KBi(SeO4)(IO3)Cl exhibits a three-dimensional tunnel framework that is composed of three types of atomic groups, i.e., tetrahedral SeO4, trigonal pyramidal IO3, and polyhedral BiO6Cl. Both IO3 pyramid and BiO6Cl polyhedron are in strongly acentric coordination due to the influence of I5+ and Bi3+ lone electron pairs. The measurement of UV–vis–NIR spectra for powder KBi(SeO4)(IO3)Cl indicates that the material is a wide band gap semiconductor with Eg = 3.9 eV. Theoretical analysis shows that the electron transition from Bi 6p to O 2p states in the BiO6Cl unit dominates the optical absorption edge. Thermal stability and IR spectrum were also analyzed for the material.

Structure analysis and luminescence properties of red-emitting iodide scintillators with potassium-hexachloroplatinate(IV) type structure

Halide compounds with chemical formula A2MX6 (A: alkali metal or Tl, M: tetravalent metal, X: halogen) have previously been reported as intrinsic scintillators. However, some application fields e.g., utilizing waveguides, require novel scintillators with emission wavelengths longer than that of Cs2HfI6 as bright and red/infrared scintillators. Thus, in this study, cation-substituted Cs2HfI6 crystals (Rb2HfI6, K2HfI6, Cs2ZrI6, Rb2ZrI6, and K2ZrI6) were grown using the vertical Bridgman method, and their crystal structures were analyzed via single-crystal X-ray diffraction. The crystal structures of Cs2HfI6 and Cs2ZrI6 were determined to be cubic (space group: Fm3̅m), Rb2HfI6 and Rb2ZrI6 were tetragonal (space group: P4/mnc), and K2HfI6 and K2ZrI6 were monoclinic (space group P21/c). In addition, the emission spectra of Rb2HfI6, K2HfI6, Rb2ZrI6, and K2ZrI6 showed that their peaks exhibited a 25 nm red-shift in comparison with that of Cs2HfI6, whereas those of Cs2ZrI6 did not. For A2MI6 compounds, the emission was effectively determined by A-site cation substitution. Moreover, the pulse-height spectra were successfully measured for A2HfI6. The scintillation light outputs of Cs2HfI6, Rb2HfI6, and K2HfI6 were estimated to be approximately 60,000, 40,000, and 33,000 photons/MeV, respectively.

Nonlinear optical properties of novel crystalline complexes of cobalt (II) and nickel (II) with 4-bromo-3-methyl-1H-pyrazole: combined experimental and computational study

Two new isostructural cobalt [Co(II)(C4H5BrN2)4(Cl)2], I and nickel [Ni(II)(C4H5BrN2)4(Cl)2], II complexes were synthesized for linear and nonlinear optical (NLO) responses using the finite field method. The synthesized complexes were characterized using elemental analysis, infrared and H-NMR spectroscopy, TG/DSC analysis, and X-ray crystallography. The crystal analysis indicates that both complexes I and II are mononuclear, and crystallize in the monoclinic space group P21/c. The metal ion in each complex is six coordinated with four nitrogen atoms (from 4-bromo-3-methyl-1H-pyrazole ligand) and two chloride ligands adopting octahedral coordination geometry. Furthermore, the computational predictions for molecular geometries and average third-order nonlinear polarizabilities of I and II are made in current study. The average theoretically predicted third-order nonlinear polarizabilities 〈γ〉 of I and II are 95.50 × 10−36 and 91.25 × 10−36 esu, respectively. The 〈γ〉 amplitudes values of complexes I and II are ∼5.26 and ∼5.0 times greater than the prototype NLO molecule of para-nitroaniline (p-NA) at same level of theory, which indicates their decent potential as efficient NLO materials.

Zur Kenntnis ternärer Oxoarsenate(III) dreiwertiger Lanthanoide: Synthese und Charakterisierung von LnAsO3- und Ln 2As4O9-Vertretern mit Ln = La und Ce sowie Ln = Pr, Nd, Sm–Gd

Abstract The title compounds have been prepared from the elemental lanthanoids and arsenic sesquioxide in 1:1 and 2:3 molar ratios in the presence of a cesium-halide flux at temperatures near 1000 °C generating elemental arsenic as the by-product. With the preparation of B-type La[AsO3] crystallizing in the monoclinic space group P21/c with the lattice parameters a = 904.03(8), b = 789.96(7), c = 837.49(7) pm and β = 103.354(3)°, both A- and B-type Ln[AsO3] representatives are now available for lanthanum and cerium. The crystal structure consists of two crystallographically distinct Ln 3+ cations with eight- or ninefold coordination by O2− anions. The Ln 3+ cations are arranged in layers of (Ln1)3+ and corrugated bilayers of (Ln2)3+ cations in the (100) plane. The two different As3+ cations appear in [AsO3]3− units, which differ mainly in their environment of Ln 3+ cations. The successful synthesis of the compounds Ln 2As4O9 (Ln = Pr, Nd, Eu and Gd) reported here on the one hand closes the structural gap between cerium and neodymium, and on the other hand also extends the spectrum of ternary oxoarsenates(III) of lanthanoids to gadolinium, with the neodymium compound for the first time at standard temperature. The crystals of the Ln 2As4O9 compounds are triclinic (space group: P 1 ‾ $P\overline{1}$ ) with lattice parameters nicely reflecting the lanthanoid contraction from a = 690.61(5), b = 768.95(6), c = 959.72(8) pm, α = 96.927(3), β = 103.812(3), γ = 104.441(3)° for Pr2As4O9 to a = 676.12(5), b = 751.58(6), c = 951.57(8) pm, α = 96.462(3), β = 103.678(3), γ = 104.409(3)° for Gd2As4O9 with two crystallographically independent lanthanoid(III) positions. The oxidic environments on these sites show the shape of square antiprisms with significant distortions, but (Ln2)3+ has a ninth oxygen contact in a capped antiprism. The linkage of the polyhedra creates layers in the ab plane, which are separated by the complex anions of arsenic. The oxoarsenate(III) units [AsO3]3− are linked by sharing oxygen corners to form both dinuclear [As2O5]4− and cyclic tetranuclear [As4O8]4− complex anions, which is why the compounds can also be represented with their structured molecular formula Ln 4[As2O5]2[As4O8]. The free electron pairs of the arsenic(III) cations point into channels, which are built up in the crystal structure along [010].

Structural, vibrational, thermal and computational studies of new organo-selenate compounds bis(4-carboxyanilinium) selenate and bis(4-carboxyanilinium) selenate trihydrate

Two new organo-selenate compounds, bis(4-carboxyanilinium) selenate trihydrate (B4-CASeO4·3H2O) and bis(4-carboxyanilinium) selenate (B4-CASeO4) were synthesized and it was found to have antioxidant, antibacterial and antifungal activities. These crystals were characterized by single-crystal X-ray diffraction, DSC, IR spectroscopy and computational analysis. B4-CASeO4·3H2O crystallizes in the triclinic space group, P -1, Z = 2 and B4-CASeO4 crystallizes in the monoclinic space group, P21/c, Z = 4. Both crystal structures consist of organic and inorganic layers which are interlinked by ionic and extensive N—H….O hydrogen-bonding interactions, between the NH3+ group of the cation and O-atom of anion. Such an extensive three dimensional hydrogen-bonding framework stabilize the crystal structure. In B4-CASeO4 crystal the cation, 4-CA exists as a dimer due to strong OH···O hydrogen bonding interaction. Such dimer formation is not observed in B4-CASeO4·3H2O. The fingerprint plots obtained using CrystalExplorer21 indicated that, the most prominent interaction in both crystals corresponds to the short O···H contacts and also the other interactions were similar. However their values were different indicating the intermolecular interactions were quite different. The intermolecular interaction topology of B4-CASeO4·3H2O and B4-CASeO4 has been quantitatively analyzed using the computational tool of energy framework analysis.

A New Nickel(II) Complex Derived From Bisthiocarbohydrazone: Synthesis, Characterization, Crystal Structure and Antioxidant Activity

A new complex with composition [Ni(L)(PPh3)] (PPh3 = triphenylphosphine) was obtained from the reaction of 1,5-bis(salicylidene)thiocarbohydrazone (L) with an equimolar amount of [NiCl2(PPh3)2]. The complex was identified by FT-IR, 1H NMR and UV-Vis spectroscopic methods and elemental analysis. The solid state structure of [Ni(L)(PPh3)] was established by X-ray diffraction analysis. It was determined that the complex, whose nickel center has a distorted square planar configuration, crystallizes in the monoclinic space group I2/c. Bisthiocarbohydrazone (L) binds to the nickel center through its phenolate O, azomethine N and thioenolate S atoms in a dianionic tridentate mode. The antioxidant capacity of L and Ni(II) complex was examined using the CUPRAC (cupric reducing antioxidant capacity) method. Also, the DPPH (1,1-Diphenyl-2-picrylhydrazyl) method was used to test free radical scavenging activity of the compounds. Antioxidant activity results showed that L exhibited better activity than Ni(II) complex.

Li4Ln[PS4]2Cl: Chloride-Containing Lithium Thiophosphates with Lanthanoid Participation (Ln = Pr, Nd and Sm)

The synthesis and structural analysis of three new chloride-containing lithium thiophosphates(V) Li4Ln[PS4]2Cl with trivalent lanthanoids (Ln = Pr, Nd and Sm) are presented and discussed. Single crystals of Li4Sm[PS4]2Cl were obtained and used for crystal structure determination by applying X-ray diffraction. The other compounds were found to crystallize isotypically in the monoclinic space group C2/c. Thus, Li4Sm[PS4]2Cl (a = 2089.31(12) pm, b = 1579.69(9) pm, c = 1309.04(8) pm, β = 109.978(3)°, Z = 12) was used as a representative model to further describe the crystal structure in detail since Li4Pr[PS4]2Cl and Li4Nd[PS4]2Cl were confirmed to be isotypic using powder X-ray diffraction measurements (PXRD). In all cases, a trigonal structure in the space group R3¯ (e.g., a = 1579.67(9) pm, c = 2818.36(16) pm, c/a = 1.784, Z = 18, for Li4Sm[PS4]2Cl) displaying almost identical building units worked initially misleadingly. The structure refinement of Li4Sm[PS4]2Cl revealed bicapped trigonal prisms of sulfur atoms coordinating the two crystallographically distinct (Sm1)3+ and (Sm2)3+ cations, which are further coordinated by four anionic [PS4]3− tetrahedra. The compounds also contain chloride anions residing within channel-like pores made of [PS4]3− units. Eight different sites for Li+ cations were identified with various coordination environments (C.N. = 4–6) with respect to chlorine and sulfur. EDXS measurements supported the stoichiometric formula of Li4Ln[PS4]2Cl, and diffuse reflectance spectroscopy revealed optical band gaps of 2.69 eV, 3.52 eV, and 3.49 eV for Li4Sm[PS4]2Cl, Li4Nd[PS4]2Cl, and Li4Pr[PS4]2Cl, respectively. The activation energy for Li+-cation mobility in Li4Sm[PS4]2Cl was calculated as Ea(Li+) = 0.88 eV using BVEL, which indicates potential as a Li+-cation conductor.

Synthesis, crystal structure, Hirshfeld surface analysis, DFT, molecular docking and in vitro antitumor studies of (2E)-2-[4-(diethylamino)benzylidene]-N-ethylhydrazinecarbothioamide

The crystal structure and spectral characterization of a new proligand, (2E)-2-[4-(diethylamino)benzylidene]-N-ethylhydrazinecarbothioamide is described. The compound was crystallized in the monoclinic space group P21/c; Z = 8, V = 3192.7(8) Å3 with unit cell parameters a = 26.232(4) Å, b = 7.9196(10) Å, c = 15.369(3) Å,α = 90°, β = 90.217(6)° and γ = 90°. There are two independent molecules in the asymmetric unit. The crystal structure reveals that the compound exists in the thione form and S1 and N2 are at E configuration to each other with respect to N3–C12 bond. Similarly, S2 and N6 are trans to each other with respect to N7–C26 bond in the second molecule of the asymmetric unit. The packing of the molecules in the crystal lattice is stabilized by intermolecular hydrogen bonds, which are quantified with Hirshfeld surface analysis. The synthesized compound was characterized by IR, UV–vis, 1H and 13C NMR spectra. DFT study indicates the molecular chemical stability with a HOMO-LUMO energy gap of 3.79 eV. The molecule is soft with preference for NS coordination mode. The azomethine nitrogen and thione sulfur region are electron rich and can act as a nucleophilic site to bind with the electrophilic regions of DNA or protein receptors. The in silico docking study with 1BNA suggests that the compound can fit comfortably in the curved shape of the DNA target like a minor groove mode of binding. The in vitro cytotoxicity of the compound, which was screened for DLA tumour cells aspirated from the peritoneal cavity of tumor bearing mice, is indicative of its antitumor potential.

Synthesis and Crystal Structure of Dimethyl{N-[(2-oxy-1-naphthyl)methylene]leucinato}silicon

The title compound was prepared by reaction of the Schiff base ligand N-(2-hydroxy-1-naphthylidene)leucine with dichlorodimethylsilane in the presence of triethylamine as base. The resulting pentacoordinate silicon complex was characterized by NMR, IR, UV-Vis spectroscopy and melting point. The structure was confirmed by single-crystal X-ray diffraction data. It crystallizes in the monoclinic space group Ic with unit cell dimensions a = 7.2030(6), b = 22.9842(14), c = 10.8946(12) Å, β = 96.141(7)°, V = 1793.3(3) Å3, Z = 4.

Novel Non-Centrosymmetric NdSr4O(BO3)3 Borate and Nd(Ca1−xSrx)4O(BO3)3 Solid Solutions: Preparation, Crystal Structures, Thermal Expansion and Optical Properties

A novel non-centrosymmetric NdSr4O(BO3)3 borate and solid solutions of Nd(Ca1−xSrx)4O(BO3)3 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1.0) were synthesized by solid-state reactions as well as crystallization from a melt. The crystal structures of the Nd(Ca1−xSrx)4O(BO3)3 solid solutions with x = 0.2, 0.5 and 1.0 were determined from single crystal X-ray diffraction data and refined in the monoclinic space group Cm to Robs = 0.028, 0.034 and 0.028, respectively. The thermal expansion of the samples with x = 0, 0.2 and 0.5 was investigated using powder high-temperature X-ray diffraction in the temperature range of 25–1000 °C. A similarity of the thermal and compositional (Ca-Sr substitution) deformations of Nd(Ca1−xSrx)4O(BO3)3 solid solutions is revealed: Heating of Nd(Ca0.5Sr0.5)4O(BO3)3 by 1 °C leads to the same deformations of the crystal structure as increasing the amount of Sr atoms in Nd(Ca0.5Sr0.5)4O(BO3)3 by 0.26 at% Sr. The SHG signal of the series of Nd(Ca1−xSrx)4O(BO3)3 solid solutions has a maximum at approximately x = 0.2.

1-Ethyl-4-isopropyl-1,2,4-triazolium bromide.

An ionic compound consisting of a triazolium cation and bromide anion, C7H14N3 +·Br-, has been synthesized and structurally characterized using single-crystal X-ray diffraction and NMR. The compound crystallizes in the monoclinic space group P21/m with the non-hydrogen atoms of one cation lying on general positions and the others lying on a mirror plane. One bromide ion also lies on the mirror. The extended structure exhibits only weak inter-molecular inter-actions between heterocyclic C-H groups and Br- ions.

A New Zn(II) Azido Complex of L-Arginine: X-ray Crystal Structure, Hirshfeld, and AIM Studies

The synthesis and X-ray crystal structure analyses of the azido complex [Zn(N3)(Arg)2](N3)·3H2O, where Arg is L-arginine, were presented. The molecular structure of the complex was further studied using FT-IR spectra as well as atoms in molecules (AIM) theory. An analysis of the crystal data indicated monoclinic crystal system and P21 space group with a = 13.0283(5) Å, b = 15.2032(7) Å, c = 13.3633(6) Å, β = 114.3580(10)°, V = 2411.28(18) Å3, and Z = 4. Two of the [Zn(N3)(Arg)2](N3)·3H2O formulae represent the asymmetric unit of this complex where the geometric parameters of both units are slightly different. In [Zn(N3)(Arg)2](N3)·3H2O, the central Zn(II) ion is penta-coordinated with two Arg molecules as a bidentate ligand and one terminally coordinated azide ion. Each of the two Arg molecules are located trans to one another and coordinated with the Zn(II) via the N and O atoms of the amino and carboxylate groups, respectively. Hence, Zn(II) is five-coordinated and has a distorted square pyramidal coordination geometry. The supramolecular structure of the [Zn(N3)(Arg)2](N3)·3H2O complex was inspected using the Hirshfeld analysis. The O···H (26.6–28.4%), H···H (32.3–35.3%), and N···H (30.4–34.0%) contacts are the most significant interactions in the crystal structure of the [Zn(N3)(Arg)2](N3)·3H2O complex. The Zn–N, and Zn–O bonds have slight covalent interactions based on the AIM study.

Synthesis, crystal structure and thermal behavior of tetra-kis-(3-cyano-pyridine N-oxide-κO)bis-(thio-cyanato-κN)cobalt(II), which shows strong pseudo-symmetry.

The title compound, [Co(SCN)2(C6H4N2O)4], was prepared by the reaction of cobalt(II)thio-cyanate with 3-cyano-pyridine N-oxide in ethanol. In the crystal, the cobalt(II) cations are octa-hedrally coordinated by two terminal N-bonded thio-cyanate anions and four O-bonded 3-cyano-pyridine N-oxide coligands, forming discrete complexes that are located on centers of inversion, hence forming trans-CoN2O4 octa-hedra. The structure refinement was performed in the monoclinic space group P21/n, for which a potential lattice translation and new symmetry elements with a fit of 100% is suggested. The structure can easily be refined in the space group I2/m, where the complexes have 2/m symmetry. However, nearly all of the reflections that violate the centering are observed with significant intensity and the refinement in P21/n leads to significantly lower R(F) values (0.027 versus 0.033). Moreover, in I2/m much larger components of the anisotropic displacement parameters are observed and therefore, the crystal structure is presented in the primitive unit cell. IR investigations confirm that the anionic ligands are only terminally bonded and that the cyano group is not involved in the metal coordination. PXRD investigations show that a pure crystalline phase has been obtained and measurements using simultaneously thermogravimetry and differential thermoanalysis reveal that the compound decomposes in an exothermic reaction upon heating, without the formation of a coligand-deficient inter-mediate phase.

Characterization and magnetic properties of two mixed-valence compounds A2MnⅡMn2III(SeO3)6 (A = Sr and Ba)

A2MnⅡMn2III(SeO3)6 (A = Sr and Ba) are found to have a monoclinic space group P21/c, where Mn3+ ions form a distorted honeycomb lattice centred by the Mn2+ ions. The samples of two isostructural compounds were synthesized using a conventional hydrothermal method and characterized by many methods including EDS, XRD, FT-IR, UV–vis diffuse reflectance spectra and thermal analysis. Magnetic measurements confirm that two compounds display a similar magnetic behavior with a short-range and a long-range antiferromagnetic order at low temperature, while the metamagnetic transition can be observed under applied magnetic field. In addition, the spin-frustration effects of two compounds are also investigated.

Crystal structure, biological and docking studies of solvothermally isolated novel schiff base

Solvothermal condensation of 4-hydroxy-3-methoxy benzaldehyde and ethylenediamine resulted in single crystals of the novel Schiff base N,N'-Bis(4-hydroxyl-3-methoxybenzylidene)ethane-1,2-diamine (H2L) while the conventional method yielded microcrystalline H2L. Single crystals of H2L were characterized by various techniques, including single crystal X-ray diffraction. The structural analysis revealed crystallization of H2L in the monoclinic P21 space group with z = 4 and z′ = 2 indicating the presence of two independent H2L molecules in the asymmetric unit of the crystal structure connected by O6-H6…N2 weak contacts involving H and N atoms of the hydroxyl and amine groups respectively. The biological activities, namely DNA binding and cell viability studies of H2L, were performed. H2L exhibited potent activity against mushroom tyrosinase enzyme. In this work, in-silico docking studies have been conducted to evaluate the effective binding modes of H2L with 2y9x mushroom tyrosinase protein. The docking studies revealed minimum binding energy of -6.43 kcal mol−1 for H2L compared to the value of -3.64 kcal mol−1 for standard Kojic acid. The antibacterial performance of H2L was tested, and the results are presented.

Synthesis, crystal structure characterization and computational investigation of new thieno[2,3-b]pyridine derivatives as potent against molecule p38 alpha MAP kinase

In this study, two new thieno[2,3-b]pyridine derivatives (2 and 3) have been synthesized and characterized by single X-ray diffraction. While compound 2 crystallizes in monoclinic space group P21/c, compound 3 crystallizes in triclinic space group P. These compounds were further subjected to molecular docking simulation with p38 alpha MAP kinase to understand the binding interaction mechanism, in addition to that ADMET analysis was also performed to explore the title compounds to characterize the future drug candidate. To rationalize their structure-activity relationship, a DFT study based on the B3LYP/6-311++G** theoretical level was also done in this study.

Tetrabromidocuprate(II) complexes with diprotonated 1-hydroxy-4methyl-2-(pyridin-2-yl)-5-phenylimidazole and 1-hydroxy-2-(pyridin-2-yl)-4,5,6,7-tetrahydrobenzimidazole ligands: Relationship between the structure and magnetic properties

Two new tetrabromidocuprate(II) complexes with diprotonated 1-hydroxy-2-(pyridin-2-yl)-4,5,6,7-tetrahydrobenzimidazole (1) and 1-hydroxy-4methyl-2-(pyridin-2-yl)-5-phenylimidazole (2) were synthesized and their structure established from single-crystal X-ray data. Compounds crystallized in the monoclinic space groups P21/n and P21/c, respectively, where tetrabromidocuprate anions formed magnetic chains as inferred from the distances between the halide ions of different [CuBr4]2− units. Magnetization measurements showed that both compounds behave as well-isolated uniform S = 1/2 antiferromagnetic chains described by the one-dimensional Heisenberg antiferromagnetic model with intra-chain exchange interaction 2 J = 23 K (1) and 2 J = 33 K (2) (the Hamiltonian Hˆ=2J∑SˆiSˆi+1). Electron paramagnetic resonance, optical absorption, and density functional theory investigations provided complementary results for 1 and 2. A calculation of exchange coupling constants gave values of 2 J = 24 K (1) and 2 J = 39 K (2), in good agreement with the experiment. The quantum theory of atoms in molecules and non-covalent interaction analyses showed that halogen bonding determined the exchange interaction between [CuBr4]2− units in magnetic chains of these cation–anion compounds.