A restudy of the crystal structure of tetraaquastrontium dicitratoborate trihydrate

The crystal structure of Sr(H₂O)₄[(C₁₂H₁₁O₁₄)B] · 3H₂O (I) has been restudied and determined with a higher accuracy. The crystals are monoclinic, space group P2₁/n, a = 11.405(1) Å, b = 18.814(1) Å, c = 11.987(1) Å, β = 110.79(1)°; Z = 4. The structure was refined by full matrix least-squares calculation to R = 0.0547 on 5343 unique reflections with R _int = 0.0419. The structural units of crystal I are the Sr²⁺ cation, seven water molecules, and doubly charged dicitratoborate anion, which is not equivalent to the singly charged complex dicitratoborate anion identified previously in the crystal structures of complexes of boric and citric acids. The coordination polyhedron of the Sr²⁺ cation is a distorted dodecahedron composed of four O atoms of coordinated water molecules and four O atoms of two complex anions. The crystal packing of I is layered. Thirteen independent O-H…O and O-H…, O′ contacts form an intricate system of hydrogen bonds.     

Crystal and molecular structures of the copper dichloride complex with 1-isopropenylimidazole

Crystal and molecular structures of the [CuL₂Cl₂] complex (L is 1-isopropenylimidazole) (I) are determined (R = 0.038, (wR ₂ = 0.092 for 2026 reflections with F _o ≥ 4σ(F _o); R ₁ = 0.123, wR ₂ = 0.117 for all reflections)) and compared with the structure of the known cobalt complex of analogous composition [CoL₂Cl₂] (II). Unlike complex II with the usual tetrahedral environment of the cobalt atom, the structure of the coordination polyhedron of the copper atom in compound I is intermediate between tetrahedron and square (the average dihedral angle between the ClCuN planes is 35.9°, and the ClCuCl (147.5°) and NCuN (163.1°) angles are much larger than the ClCuN angle of 90.1°–93.1°). The Cu-N (1.975(3), 1.959(3) Å) and Cu-Cl bonds (2.291(1), 2.278(1) Å) in complex I are typical of the copper(II) compounds. Different spatial structures of the 1-alkenylimidazole cycles in complexes I and II are found. Different short intermolecular contacts in crystals of compounds I (Cu…Cl, Cu…H) and II (Cl…C) result in the formation of chains with different mutual arrangements of molecules of the complexes.     

Mixed-Ligand Complexation of Zinc and Cobalt(II) Complexonates with Amino Acids in an Aqueous Solution

The formation of mixed-ligand complexes in the M(II)–Nta and Ida–L systems (M = Co, Zn; L = His, Orn, Lys, Gly, Im, en), where Ida and Nta are the residues of iminodiacetic and nitrilotriacetic acids, was studied by pH-metry, calorimetry, and NMR spectroscopy. The thermodynamic parameters (logK, Δ _r G⁰, Δ _r H, Δ _r S) of formation for these complexes were determined at 298.15 K and an ionic strength I = 0.5 (KNO3). The most probable pattern of coordination between a complexone and an amino acid in mixed-ligand complexes was revealed.     

Synthesis and structure of the [Co(NioxH)<Subscript>2</Subscript>(Thio)<Subscript>2</Subscript>]<Subscript>2</Subscript>SO<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O complex compound

A new Co(III) complex of 1,2-cyclohexanedionedioxime and thiocarbamide with an SO ₄ ^2? anion and solvation water molecules in the outer sphere has been synthesized and its structure has been defined. Orthorhombic crystals, a = 11.659(2) Å, b = 26.448(5) Å, c = 30.142(6) Å, V = 9295(3) Å ³, Z = 8, d_calc = 1.599 g/cm³, space group Pbca; final R index is 0.0578 for 8221 reflections with I > 2σ(I). In the octahedral Co(III) complex, two 1,2-cyclohexanedionedioxime residues lie in the equatorial plane, while two thiocarbamide molecules are in the axial plane. Intramolecular bonds: N-H…O and O-H…O type hydrogen bonds and π-π interactions that stabilize the complex cations. In crystal, the components are linked by N-H…O and O-H…O hydrogen bonds into a 3D framework.     

Crystallochemical study of ruthenium(III) tris-dipivaloylmethanate

The structure of ruthenium(III) dipivaloylmethanate is determined by single crystal X-ray diffraction at temperature of 150 K. The crystallographic data for C₃₃H₅₇O₆Ru are as follows: a = 9.6119(11) Å, b = 17.4603(19) Å, c = 21.519(2) Å, β = 95.187(2)°, C2/c space group, V = 3596.7(7) ų, Z = 4, d_calc = = 1.202 g/cm³, R = 0.0642. The structure is molecular, the metal atom coordinates six oxygen atoms of three ligands of β-diketone. The Ru–O distances are in the range of 1.99 Å to2.03 Å. The complexes have a distorted single layer hexagonal packing with the Ru…Ru distances being 9.84 Å within the layer, and 10.93 Å between the layers.     

Molecular structure investigation of Z-3N(2-ethoxyphenyl)-2-N′(2-ethoxyphenyl)-imino-thiazolidin-4-one by <Emphasis Type="Italic">ab initio</Emphasis>, DFT and X-ray diffraction methods

We report here the synthesis of the Z-3N(2-ethoxyphenyl)-2-N′(2-ethoxyphenyl)-imino-thiazolidin-4-one compound. The crystal structure is determined by X-ray diffraction. The compound crystallizes in the monoclinic system with the space group P2_1/n and cell parameters: a = 9.4094(10) Å, b = 9.3066(10) Å, c = 20.960(2) Å, β = 99.0375(10)°, V = 1812.7(3) ų and Z = 4. The structure is refined to final R = 0.05 for 2083 observed reflections. The molecule in the crystal exhibits the intermolecular hydrogen bonds of C–H…O, C–H…N, and C–H…S types. Ab initio calculations are also performed at Hartree–Fock (HF) and density functional theory (DFT) levels. The full HF and DFT geometry optimization is carried out using the 6-31G(d,p) basis set. The observed molecular structure is compared with that calculated by both HF and DFT methods. The optimized geometry of the titled compound is found to be consistent with the structure determined by X-ray diffraction.     

Synthesis and crystal structure of Fe(III) and Al(III) complexes with 2-diphenylacetyl-1,3-indandione

Iron(III) and aluminum(III) complexes with 2-diphenylacetyl-1,3-indandione (HL) have been synthesized. The structures of the obtained compounds FeL₃(I) and AlL₃(II) were studied. The isostructural crystals are monoclinic, I: Z = 8, space group P2_1/c, a = 16.061(3) Å, b = 16.658(3) Å, c = 22.015(4) Å, β = 111.41(3)°; II: Z = 8, space group P2_1/c, a = 16.115(14) Å, b = 16.476(8) Å, c = 21.949(20) Å, β = 111.04(11)°. The structural units of crystals I and II are neutral molecules in which each ligand is bidentately coordinated to a central metal atom through the oxygen atom of the acyl keto group and an oxygen atom of the indandione fragment to form a six-membered chelate ring. In the crystals, neutral molecules I and II form pseudodimers due to stacking of indandione moieties of two adjacent coordination spheres and additional C-H…O contacts. Each pseudodimer is in contact with six neighboring dimers also through hydrogen bonds C-H…O to form an infinite framework.     

Spacer-armed binuclear copper(ii) complexes with salicylidene hydrazones of N-benzoylaminodicarboxylic acids

The structure and EPR spectra of copper(II) complexes with bis(salicylidene)hydrozones of N-benzoyl-L-aspartic and N-benzoyl-L-glutamic acids have been described. The compounds have been studied by chemical and thermal analyses, IR spectroscopy, and EPR spectroscopy. The molecular and crystal structure of the copper(II) complex with bis(salicylidene)hydrozone of N-benzoyl-L-aspartic acid (H₄L) of composition [Cu₂L · 2Py] · 2CH₃OH · H₂O has been determined by X-ray single-crystal diffraction. The crystals are monoclinic: a = 10.3316(7) Å, b = 16.7552(9) Å,c = 11.0137(6) Å, β = 105.758(3)°, space group P2₁, Z = 2. The complex has a polymeric structure composed of alternating copper-containing binuclear fragments bound to each other either via phenoxy bridges or via an aliphatic spacer (the Cu…Cu distances are 3.471 Å and 8.939 Å, respectively). The EPR spectra of the solutions of the complexes under study shows an isotropic signal comprising seven HFS lines due to two equivalent copper nuclei with the spin Hamiltonian parameters g = 2.115–2.122 and a _Cu = (36.1–36.9) × 10^?4 cm^?1, which indicates the reaization of weak exchange coupling of the paramagnetic centers.     

Characterization of the adducts of bis(O-isoamyldithiocarbonato)nickel(II) with heterocyclic amines and X-ray structure of bis(O-isoamyldithiocarbonato)-bis(3-bromopyridine)nickel(II)

A series of six-coordinated Ni(II) complexes, with the general formula Ni(Xan)L₂ (where Xan = = isoamyldithiocarbonato and L = 2-bromopyridine, 3-bromopyridine, 4-acetylpyridine, 3-hydroxypyridine and 2-methoxypyridine) are synthesized and characterized by the elemental analysis and various physicochemical techniques such as magnetic susceptibility and conductivity measurements, UV-visible and infrared spectral data. Based on the electronic spectra and magnetic susceptibility measurements, an octahedral geometry is proposed for all the complexes. IR spectral data show that in all these complexes substituted pyridines coordinate to the metal ion through nitrogen atoms occupying the fifth and sixth axial positions, whereas O-alkyldithiocarbonate acts as a monoanion bidentate ligand and occupies the planar positions of octahedral structures. The structure of the adduct with 3-bromopyridine is elucidated by the single crystal X-ray diffraction method. The complex crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.5855(4) Å, b = 9.4984(6) Å, c = 12.4518(8) Å, α = 87.944(5)°, β = 78.843(5)°, γ = 77.794(5)°. The crystal structure of the molecule is stabilized by intermolecular C–H…S and C–H…π interactions.     

Compositions and structures of nanoparticles of pentagonal axial symmetry <Emphasis Type="Italic">D</Emphasis><Subscript>5<Emphasis Type="Italic">d</Emphasis></Subscript>: Nanotubes

The method of determination of the structure and the number of atoms in the shells of nanoparticles as a function of the arrangement of atoms at the symmetry elements of a symmetry group has been developed. The formulas for the calculation of the number of particles with symmetry group D _5d are reported. The number of particles in these shells is determined by three structurally invariant numbers and the “quantum number” of the group order n. The classification of all possible nanostructures with symmetry group D _5d is given: C _θ+10z , z = 0, 1, 2, …, where the basic shells are C _θ = C ₂, C ₁₀, C ₁₂. The sum rule has been obtained for the coordination numbers of shell sites located at symmetry axes. Pentagonal axial nanoparticles are shown to be the initial shells for obtaining (5,5) and (10,10) armchair nanotubes or (5,0) and (10,0) zigzag nanotubes. The general formula of these nanotubes closed with icosahedral and dodecahedral caps is N _20+10p , N _60+10p (p = 1, 2, …). The graphical constructions of all classes of nanoparticles and nanotubes of the pentagonal axial type are reported.     

Silver-based coordination complexes of carboxylate ligands: crystal structures,luminescence and photocatalytic properties

The complexes [Ag₄(dpe)₄]·(btec) (1) and [Ag₄(bpy)₄]·(btec)·12H₂O (2) (dpe = 1,2-di(4-pyridyl)ethylene, bpy = 4,4′-bipyridine, H₄btec = 1,2,4,5-benzenetetracarboxylic acid) have been synthesized in aqueous alcohol/ammonia by slow evaporation at room temperature and characterized by elemental analysis, single-crystal X-ray diffraction, FTIR, UV–Vis and luminescence spectroscopies. Both complexes are composed of 1D infinite cationic [Ag/dpe(bpy)] _n ⁿ⁺ chains and discrete btec^4? anions. Their three-dimensional supramolecular structures are built up of cationic sheets formed from [Ag/dpe(bpy)] _n ⁿ⁺ units via weak Ag…Ag and Ag…N interactions, plus anionic btec^4? sheets featuring electrostatic, π–π and hydrogen bonding interactions. Both complexes exhibited photocatalytic activity for the decomposition of methyl orange under UV light irradiation.     

Experimental and theoretical prediction of the redox potentials of noradrenaline and its supramolecular complex with glycine

The redox reaction of N-protonated noradrenalin (NA) is a two-proton-two-electron reaction in aqueous solution. NA can be oxidated to N-protonated noradrenalin quinone (NAquinone). The standard electrode potential (E⁰) value of NA/NAquinone couples is obtained experimentally with cyclic voltammetry (CV) and theoretically with two methods at B3LYP/6-311++G(d, p) level. The theoretical E⁰ value of NA/NAquinone couples is in good agreement with experimental ones and close to each other. Glycine (Gly) can form hydrogen bonds with NA in physiological environment. The E⁰ values of NA–Gly/NAquinone–Gly couples are predicted experimentally and theoretically. Hydrogen bond interaction weakens the electrondonation abilities of NA.     

Syntheses,characterization, crystal structures and fluorescence property of Zinc(II) complexes with Schiff bases

Two new mononuclear Schiff base zinc(II) complexes, [ZnCl₂(L¹)] ? MeOH (I) and [Zn(L²)₂] (II) (L¹ = 2-bromo-4-chloro-6-[(2-ethylammonioethylimino)methyl]phenolate; L² = 2-bromo-4-chloro-6-(isopropyliminomethyl)phenolate), have been prepared and characterized by elemental analyses, infrared and UV-Vis spectroscopy, and single-cyrstal X-ray diffraction (CIF files CCDC nos. 1408962 (I), 1408961 (II)). Complex I crystallizes in the triclinic space group \(P\overline 1\) with unit cell dimensions a = 9.859(1), b = 13.015(2), c = 19.817(3) Å, α = 73.591(2)°, β = 76.032(2)°, γ = 82.966(2)°, V = 2363.0(5) ų, Z = 4, R ₁ = 0.0925, and wR ₂ = 0.2257. Complex II crystallizes in the monoclinic space group P2₁/c with unit cell dimensions a = 7.6387(7), b = 22.307(2), c = 21.443(2) Å, β = 96.216(3)°, V = 3632.4(6) ų, Z = 8, R ₁ = 0.0651, and wR ₂ = 0.1100. The both Zn atoms in I is four-coordinated in a tetrahedral geometry by the NO donor set of the Schiff base ligand, and two Cl ligands. The Zn atom in II is in a tetrahedral geometry by two N and two O atoms from two Schiff base ligands. Crystals of the complexes are stabilized by hydrogen bonds and weak π…π interactions. Fluorescence property of the complexes have been determined.     

2-(diphenylphosphinylmethoxy)aniline: Synthesis,vibrational spectra,and crystal structure

The synthesis, vibrational spectra, and X-ray diffraction analysis results for 2-(diphenylphosphinylmethoxy) aniline, 2-[(C₆H₅)₂P(O)OCH₂]C₆H₄NH₂(I), are described. The crystals are monoclinic: a = 18.4515(17) Å, b = 10.5421(12) Å, c = 17.897(2) Å, β = 104.479(8)°, V = 3370.7(6) ų, Z = 8, space group P2₁/c, R = 0.0546 for 1770 reflections with I > 2σ(I). The unit cell contains two crystallographically independent molecules Ia and Ib joined by an N-H …O hydrogen bond between a hydrogen atom of the amino group of aniline in molecule Ia (Ib) and the phosphoryl oxygen atom of molecule Ib (Ia) (O…H 2.18 and 2.19 Å, N…O, 2.979(5) and 3.000(5) Å; NHO angle, 154° and 157°).     

Crystal structure of adducts of copper(II) acetylacetonate and hexafluoroacetylacetonate with 4-aminopyridine

Single crystal X-ray diffraction is used to investigate two synthesized β-diketonate complexes of copper(II) with aminopyridine: Cu(4-NH₂Py)(aa)₂ (I) and Cu(4-NH₂Py)(hfa)₂ (II). The crystals of I and II have a monoclinic system; the unit cell parameters of I are: P2₁/n space group, a = 8.2921(3) Å, b = 14.7243(5) Å, c = 13.4970(4) Å, β = 102.426(1)°, V = 1609.32(9) ų, Z = 4; for II: C2/c space group, a = 23.5704(5) Å, b = 11.4977(2) Å, c = 16.0285(3) Å, β = 109.265(1)°, V = 4100.6(1) ų, Z = 8. The structures of I and II are molecular; they are composed of isolated molecules. The coordination polyhedron of the copper atom is formed by the O atoms of two acetylacetonate ligands (Cu-O 1.940(2)–2.171(2) I and the O atoms of two hexafluoroacetylacetonate ligands (Cu-O 1.940(2)–2.215(3) Å) in II. The molecules of 4-NH₂Py are bonded to the copper atom via the nitrogen atom of the aromatic ring (Cu-N 2.008(2) Å in I and Cu-N 1.978(3) Å in II). Noncoordinated amino groups join the molecules of the complexes together by means of N-H…O hydrogen bonds.     

Structural characterisation and photoluminescence of a pyridine–diimine compound

A pyridine–diimine compound N,N′-[pyridine-2,6-diyldi(E)methylylidene]bis(4-chloroaniline) is synthesised by a Schiff base condensation of 2,6-diformylpyridine with 4-chloroaniline in methanol and characterised by spectroscopic and analytical techniques. The molecular structure of the compound is determined by the single crystal X-ray diffraction study. The compound crystallizes in the monoclinic crystal system, I2/c space group with unit cell parameters a = 7.0843(12) Å, b = 6.1909(11) Å, c = 36.262(6) Å, β = 91.576(3)°, V = 1589.8(5) ų and Z = 4. There is an intermolecular hydrogen bonding in the molecule resulting in a 1D hydrogen bonding chain and these hydrogen bonding chains are linked by Cl…HC(aromatic) interactions forming a 2D network. Crystal packing of the compound is determined by Cl…HC and π–π interactions. In the fluorescence emission spectra in CH₃CN, DMF, DMSO and EtOH, the compound shows only one emission maximum.     

Synthesis,DFT calculations and characterisation of new mixed Pt(II) complexes with 3-thiolanespiro-5<Emphasis Type="Italic">′</Emphasis>-hydantoin and 4-thio-1<Emphasis Type="Italic">H</Emphasis>-tetrahydropyranspiro-5<Emphasis Type="Italic">′</Emphasis>-hydantoin

Cisplatin is an anticancer drug widely used in the treatment of a wide range of solid tumours (head and neck, lung, bladder etc.), testicular and ovarian cancers. Because of its severe toxicity profile and spontaneous development of drug resistance in tumours, a number of Pt(II) complexes have been synthesised and tested for anti-tumour activity. Some of the investigations have focused on using ligands bearing donor atoms other than N (e.g., S, P, O). Two new mixed Pt(II) complexes of the general formula cis-[Pt(NH₃)LCl₂] where L is 3-thiolanespiro-5′-hydantoin and 4-thio-1H-tetrahydropyranspiro-5′-hydantom were synthesised. The complexes were studied by elemental analysis, melting points, IR and ¹H NMR spectra. The hybrid DFT calculations were used for optimisation of the structure geometries of the ligands III, IV and their Pt(II) complexes V and VI. The structural parameters so calculated, such as bond lengths and angles, are in good agreement with the experimental data for similar hydantoins and their platinum complexes. The results showed that the geometries of complexes V and VI are plane square and the bounding of ligands III and IV with platinum ions is effected by the sulphur atom from the cyclic ring. The complexes thus obtained were chemically examined in comparison with previously synthesised and published complexes of the general formula cis-[PtL₂Cl₂] (VII and VIII) with the same ligands. The new compounds V and VI, as well as the previously investigated complexes (VII and VIII), were analysed for cytotoxicity in vitro on SKW-3 and HL-60 human tumour cell lines. The results showed that all the complexes exerted concentration-dependent anti-proliferative activity.     

Synthesis and crystal structure of two derivatives of benzodiazepines

Two benzodiazepine derivatives, C₂₃H₂₂N₂O (I), 2-methyl-8-methoxy-2,4-diphenyl-2,3-dihydro-1H-1,5-benzodiazepine, and C₂₂H₁₇N₃O₂Br₂ (II), 2-methyl-7-nitro-2,4-bis(4′-bromophenyl)-2,3-dihydro-1H-1,5-benzodiazepine, were studied by single crystal X-ray diffraction method. Compound (I) crystallizes in the monoclinic system, space group P2₁/c, a = 13.1703(17) Å, b = 11.1990(14) Å, c = 12.9093(16) Å, β = 107.831(2)°, V = 1812.6(3) ų, Z = 4. Compound (II) crystallizes in the monoclinic system, space group P2₁/n, a = 11.7345(12) Å, b = 12.7477(13) Å, c = 13.5965(14) Å, β = 95.221(2)°, V = 2025.4(4) ų, Z = 4. The molecules of (I) and (II) have T-shape form with the diazepine ring at the junction point. The seven membered central benzodiazepine ring in both structures adopt a twist-boat conformation. The crystal packing is stabilized by C-H…π (in I) and C-H…O (in II) interactions.     

Thermochemistry of the Reaction of Solvated Sodium Ion Clusters with Thymine in the Gas Phase: An Example of the Reaction in Microcosmic Environment

The thermochemistry of the reaction of the microsolvated Na⁺ such as [Na(H₂O) _n ; n?=?1?6]⁺, [Na(NH₃) _n ; n?=?1?6]⁺ and [Na(H₂O) _n (NH₃) _m ; n?+?m?=?2?6]⁺ with thymine (Thy), as an example of a reaction in the microcosmic environment, have been studied in this work, theoretically. It was found that the increase of the number of solvent molecules in the structure of microsolvated Na⁺ is accompanied by the decrease of the standard enthalpy (\(\Delta H_{r}^{^\circ }\)) and Gibbs free (\(\Delta G_{r}^{^\circ }\)) energies of the reaction (Thy?+?[Na(X) _n ]⁺→Thy-Na(X) _n ⁺ ; X?=?solvent molecule). Also, the calculations showed that the electronic intermolecular interaction (?E_int) between the Thy and microslovated Na⁺ decreased with the increase of solvent molecules. For the interaction of the [Na(H₂O) _n ; n?=?4, 5 and 6]⁺ ions with the Thy, there was the probability of forming of the hydrogen bond between water molecules in the structure of solvated Na⁺ and the Thy. The gas phase infrared (IR) spectra of the complexes of the microsolvated Na⁺ with the Thy for different values of n were calculated and compared with each other to follow the change in the frequency of the stretching vibration of the interaction path between the C=O group of the Thy and Na (O…Na) with n. Using the calculated values of \(\Delta G_{r}^{^\circ }\) of the reactions, the mole fractions of the complexes of microsolvated Na⁺ ions with the Thy were calculated at different humidity.