Structure and magnetic properties of Ln2[Cu(opba)]3(DMSO)6(H2O) · (H2O) compounds with LnLa-Lu exhibiting ladder-like molecular motifs

The reaction of Ln(III) ions with the precursor [Cu(opba)]²⁻ in DMSO has afforded a series of isostructural compounds of general chemical formula Ln₂[Cu(opba)]₃(DMSO)₆(H₂O) · (H₂O), where Ln(III) stands for a lanthanide ion and opba stands for ortho-phenylenebis(oxamato). The crystal structure has been solved for the Gd(III) containing compound. It crystallizes in the orthorhombic system, space group Pbn2₁ (No. 33) with a = 9.4183(2) Å, b = 21.2326(4) Å, c = 37.9387(8) Å and Z = 4. The structure consists of ladder-like molecular motifs parallel to each other. To the best of our knowledge, this is the first Ln(III)Cu(II) coordination polymer family exhibiting the same crystal structure over the whole lanthanide series. The magnetic properties of the compounds have been investigated and the magnetic behavior of the Gd(III) containing compound was studied in more detail.     

Thiodiacetato-copper(II) chelates with or without N-heterocyclic donor ligands: molecular and/or crystal structures of [Cu(tda)]n, [Cu(tda)(Him)2(H2O)] and [Cu(tda)(5Mphen)] · 2H2O (Him = imidazole, 5Mphen = 5-methyl-1,10-phenanthroline)

Three new thiodiacetato-Cu(II) chelates have been synthesized and studied by X-ray crystallography and by thermal, spectral and magnetic methods. [Cu(tda)]_n (1) is a 3D-polymer with a pentadentate tda, which acts with a fac-O₂ + S(apical)-tridentate chelating conformation and as a twofold anti, syn-μ-η¹:η¹ carboxylate bridge. In its square pyramidal Cu(II) coordination (type 4 + 1) four O(carboxylate) donors define a close regular square base, but the Cu-S(apical) bond deviates 27.4° from the perpendicular to the mean basal plane. Each anti,syn-bridging carboxylate group exhibits two C-O (average 1.26(1) Å) and two Cu-O bonds (average 1.958(7) Å), which are very similar in length to each other. In contrast, the mixed-ligand complexes of [Cu(tda)(Him)₂(H₂O)] (compound 2, distorted octahedral, type 4 + 1 + 1) and [Cu(tda)(5Mphen)] · 2H₂O (compound 3, distorted square pyramidal, type 4 + 1) have molecular structures and the tda ligand displays only a fac-O₂ + S(apical)-tridentate conformation. The Cu-S(apical) bond lengths (2.570(1), 2.623(1) or 2.573(1) Å for 1, 2 or 3, respectively) are shorter than those previously reported for closely related Cu(II)-tda derivatives. The different tda ligand roles in their Cu(II) derivatives are rationalized on the basis of crystal packing forces driving in the absence or presence of auxiliary ligands (with two or three N-donor atoms).     

Hydrolytic stability of SnCl4 and GaCl3 in the formation of [cis-SnCl4(H2O)2] · 18-crown-6 · 2H2O and [[2,2,2]cryptand + 2H][GaCl4]2

The combination of anhydrous SnCl₄ with 18-crown-6 in aqueous conditions results in formation of the non-hydrolysed product [cis-SnCl₄(H₂O)₂] · 18-crown-6 · 2H₂O. The X-ray crystal structure shows extensive intermolecular hydrogen bonding involving the cis-octahedral SnCl₄(H₂O)₂ units, the uncoordinated water molecules and the crown ether. Similarly, [2,2,2]cryptand reacts with an aqueous solution formed by adding anhydrous GaCl₃ to slightly acidic water, affording [[2,2,2]cryptand + 2H⁺][GaCl₄]₂.     

3D hydrogen bonded metal-organic frameworks constructed from [M(H2O)6][M′(dipicolinate)2] · mH2O (M/M′ = Zn/Ni or Ni/Ni). Identification of intercalated acyclic (H2O)6/(H2O)10 clusters

New heterodinuclear Zn^II/Ni^II (1) and homodinuclear Ni^II/Ni^II (2) water-soluble and air stable compounds of general formula [M(H₂O)₆][M′(dipic)₂] · mH₂O have been easily prepared by self-assembly of the corresponding metal(II) nitrates with dipicolinic acid (H₂dipic) in water solution at room temperature.  The compounds have been characterized by IR, UV/Vis and atomic absorption spectroscopies, elemental and X-ray single crystal diffraction (for 1 · 4H₂O and 2 · 5H₂O) analyses.  3D infinite polymeric networks are formed via extensive hydrogen bonding interactions involving all coordinated and crystallization water molecules, and all dipicolinate oxygens, thus contributing to additional stabilization of dimeric units, metal-organic chains and 2D layers.  In 1 · 4H₂O, the latter represent a rectangular-grid 2D framework with multiple channels if viewed along the c crystallographic axis, while in 2 · 5H₂O intercalated crystallization water molecules are associated to form acyclic nonplanar hexameric water clusters and water dimers which occupy voids in the host metal-organic matrix, with a structure stabilizing effect via host-guest interactions.  The hexameric cluster extends to the larger (H₂O)₁₀ one with an unusual geometry (acyclic helical octamer with two pendent water molecules) by taking into account the hydrogen bonds to water ligands in [Ni(H₂O)₆]²⁺.  The obtained Zn/Ni compound 1 relates to the recently reported family of heterodimetallic complexes [M(H₂O)₅M′(dipic)₂] · mH₂O (M/M′ = Cu/Co, Cu/Ni, Cu/Zn, Zn/Co, Ni/Co, m = 2, 3), what now allows to establish the orders of the metal affinity towards the formation of chelates with dipicolinic acid (Co^II > Ni^II > Zn^II > Cu^II) or aqua species (Co^II < Ni^II < Zn^II < Cu^II).     

Hydrothermal synthesis and structural investigation of silver magnesium complex of benzenehexacarboxylic acid (mellitic acid), Ag2Mg2[C6(COO)6] · 8H2O with two-dimensional layered structure

Crystal and molecular structure of silver magnesium mellitate, Ag₂Mg₂[C₆(COO)₆] · 8H₂O, was synthesized hydrothermally and characterized by X-ray structure analysis. The complex crystallizes in the monoclinic system, space group P2/n, with unit cell dimensions of a=7.4347(2), b=9.9858(2), c=14.4248(3) Å, β=99.2429(5)°, V=1055.01(4) ų, and Z=2. The structure was solved and refined to R=0.036 (R_w=0.045) for 1707 independent reflections [I_o>2σ(I_o)]. The Ag cations are coordinated by six carboxylic oxygen atoms of mellitate anions with composition of [C₆(COO)₆]⁶⁻ on the (1 0 1) plane; each mellitate anion linking three neighboring Ag distorted trigonal prisms produces a two-dimensional layered structure parallel to (1 0 1). The Mg cations, which are coordinated by four water molecules and two carboxylic oxygen atoms, are intercalated between the two-dimensional layer stacks. The carboxylate group coordinated to Mg and Ag cations serve as a tridentate ligand in that structure. The number of water molecules incorporated into the mellitate compound is controlled mainly by ionic radii of metal cation in the structure. Furthermore, the ionic radii of metal cations in the mellitate compound play an essential role in arrangement of mellitate anions in the structure, whether as a one-dimensional infinite chain, a two-dimensional layered structure, or a three-dimensional framework structure.     

Zinc complexes of 6-methyl-2-pyridinecarboxylic acid. Crystal structure of [Zn(MeC5H3NCOO)2(H2O)] · H2O

Reaction of Zn(AcO)₂ · 2H₂O with 6-methyl-2-pyridinecarboxylic acid (L) yielded a new compound [Zn(MeC₅H₃NCOO)₂(H₂O)] · H₂O. This complex was characterised by elemental analyses, conductivity measurements, infrared, ¹H and ¹³C{¹H} NMR spectroscopies and single-crystal X-ray diffraction. The crystal structure consists of discrete molecules involving a pentacoordinated Zn atom with a geometry intermediate between a trigonal bipyramid and a square pyramid and with the two N_py atoms occupying the apical sites. Treatment of the complex [Zn(MeC₅H₃NCOO)₂(H₂O)] · H₂O with 2,2^′-bipyridine (bpy) produced [Zn(MeC₅H₃NCOO)₂(bpy)]. The metallic atom in this complex displays a distorted octahedral geometry and is coordinated to two ligands (L) via the pyridine nitrogen and the carbonyl oxygen atoms and to one 2,2^′-bypyridine (bpy).     

Synthesis, characterization, crystal structures and magnetic properties of dissymmetrical double schiff base heterotrinuclear complexes: [CuL(H2O)CoCuL] · H2O · CH3OH and [(CuL)2Ni] · 2H2O

A dissymmetrical double Schiff base Cu(II) mononuclear complex: CuHL (1) (where H₃L is N-3-carboxylsalicylidene-N^′-salicylaldehyde-1,2-diaminoethane) and two trinuclear complexes: [CuL(H₂O)CoCuL] · H₂O · CH₃OH (2) and [(CuL)₂Ni] · 2H₂O (3) have been synthesized and characterized by means of elemental analyses, IR and electronic spectra. The crystal structures of two heterotrinucler complexes were determined by X-ray analysis. Each dissymmetrical cell unit of the complex 2 contains two heterotrinucler neutral molecules. In each neutral molecule, the central Co²⁺ ion is located at the site of O₆ with a distorted octahedral geometry and one terminal Cu²⁺ ion at the four-coordination site of N₂O₂, but the other one at the square-pyramidal environment of N₂O₃. Each dissymmetrical unit of the complex 3 contains a heterotrinucler neutral molecule, whose structure is similar to that of 2 except two terminal Cu²⁺ ions both at the inner site of N₂O₂. The magnetic properties of two heterotrinucler complexes have been determined in the temperature range of 5-300 K, which indicate that the interaction between the central Co²⁺ ion or Ni²⁺ ion and the outer Cu²⁺ ions is antiferromagnetic. The exchange integrals are equal to −26.2 cm⁻¹ for 2 and −50.6 cm⁻¹ for 3.     

Synthesis, characterization and bioactivity of a novel 18-metallacrown-6: [Mn(pcshz)(CH3OH)]6 · 4CH3OH · 4H2O

The reaction of N-propionyl-5-chlorosalicylhydrazide (H₃pcshz) with Mn(OAc)₂ · 4H₂O in methanol solution gives a novel 18-metallacrown-6 [Mn(pcshz)(CH₃OH)]₆ · 4CH₃OH · 4H₂O (1). The structure of 1 has been determined by X-ray diffraction and it crystallizes in the monoclinic system and space group P2(1)/n. The ring of the metallacrown is consisted of six interlink [Mn-N-N] repeated units through hydrazide N-N group bridging the ring manganese ions. And the ligand enforces the metal ions to form the stereochemistry as a propeller configuration with alternation Λ/Δ form. The largest diameters of the disc-shaped hexanuclear ring are about 8.82 Å at entrance, 9.83 Å at the central of the cavity, respectively. The solution integrity and stability of the metallacrown was studied by electrospray ionization (ESI)-MS and UV-Vis spectroscopy. The results show it is soluble and stable in methanol. Antibacterial screening data indicate the forming of the complex weakens dramatically the antibacterial activity of the ligand H₃pcshz except for Eschericha coli.     

Synthesis and crystal structure of the low-spin iron(II) complex [Fe(bpz)3](ClO4)2 · H2O (bpz=2,2-bipyrazine)

The crystal structure of the title compound [Fe(bpz)₃](ClO₄)₂ · H₂O (bpz=2,2^′-bipyrazine) has been determined by a single crystal X-ray diffraction study at 293(2) K. The complex is monoclinic, P2₁/c, a=17.263(3), b=9.983(2), c=17.921(4) Å, β=107.94(3)°, V=2938.3(10) ų, Z=4, R=0.073 and R_w=0.118. The structure is made up of tris-chelated [Fe(bpz)₃]²⁺ cations, uncoordinated perchlorate anions and crystallization water molecules. The iron atom exhibits a FeN₆ distorted octahedral geometry with average Fe-N bond length and N-Fe-N bidentate angle of 1.962(5) Å and 81.6(2)°. The value of the Fe-N bond distance and that of the room temperature magnetic moment are in agreement with a singlet ¹A₁ ground state. The structure of 1 is compared to those of other tris-chelated iron(II) complexes with bidentate nitrogen heterocycles.     

Synthesis, crystal structure and magnetic properties of a chain coordination polymer {[Cu4L2(H2O)] · H2O}n

A chain coordination polymer with the chemical formula {[Cu₄L₂(H₂O)] · H₂O}_n, has been synthesized by the assembly reaction of K₂CuL · 1.5H₂O and Cu(OAC)₂ · H₂O with a 1:1 mole ratio in methanol, where H₄L = 2-hydroxy-3-[(E)-({2-[(2-hydroxybenzoyl)imino]ethyl}imino)methyl] benzoic acid, OAC⁻ = CH₃COO⁻. The crystal structure was determined by single-crystal X-ray diffraction analysis, the compound has chain molecular structure formed by dissymmetrical tetranuclear units. The magnetic measurements showed that Cu-Cu of the complex exhibit antiferromagnetic interactions, and satisfactory fittings to the observed magnetic susceptibility data were obtained by assuming a binuclear system, and further using molecular field approximation to deal with magnetic exchange interactions between binuclear systems.     

K2[Zn(CV)2(H2O)2] · 2H2O: The first Zn(II) complex structurally characterized containing the pseudo-oxocarbon Croconate Violet (CV)

The synthesis, thermal behavior, spectroscopic characterization and crystal and molecular structure of a Zn(II) complex containing the pseudo-oxocarbon Croconate Violet (CV²⁻) dianion, namely K₂[Zn(CV)₂(H₂O)₂] · 2H₂O are reported. Thermal analysis has shown that the complex structure presents coordination and lattice water molecules. According to vibrational spectroscopy the Croconate Violet dianion is coordinated to Zn(II) center through the vicinal oxygen atoms in a chelating fashion with no involvement of CN moieties. The complex structure has been confirmed by single crystal X-ray diffraction analysis. The dianionic units [Zn(CV)₂(H₂O)₂]²⁻ adopt an slight distorted octahedral geometry in which the metallic center is surrounded by six oxygen atoms. These discrete dianionic units are connected through intermolecular hydrogen bonding giving rise to a supramolecular array extended along the crystallographic a axis.     

Hydrothermal synthesis and characterization of a zinc-substituted gallium phosphite, [H3N(CH2)2NH3]1/2 · [GaZn(HPO3)3(H2O)2]

An organically templated zinc-substituted gallium phosphite, [H₃N(CH₂)₂NH₃]_1/2 · [GaZn(HPO₃)₃(H₂O)₂] was synthesized under mild hydrothermal conditions in the presence of ethylenediamine (en) as structure-directing agent and characterized by single-crystal X-ray diffraction analysis. It crystallizes in the orthorhombic space group Pbcn with unit cell parameters: a = 18.6146(10) Å, b = 11.0454(6) Å, c = 10.9074(4) Å, V = 2242.62(19) Å³ and Z = 8. This compound has a three-dimensional framework built up from secondary building units (SBU) of Ga(III) (or Zn(II)) and HPO₃ pseudopyramid by sharing vertices. The structure displays a two-dimensional channel system running along the [0 0 1] and [0 1 0] direction with 5-, 8- and 10-membered rings. The diprotonated ethylenediamine template molecules are located in the channels. In this structure, some of the Ga(III) sites are occupied by Zn(II) atoms. The compound was also characterized by IR spectroscopy, inductively coupled plasma (ICP), X-ray photoelectron spectra (XPS), differential thermal and thermogravimetric analyses.     

Synthesis and characterisation of palladium(II) iodo complexes containing water soluble phosphine ligands. Crystal structures of [PdI2(PTA-H)2][PtI3(PTA)]2 · 2H2O and trans-[PdI2(PTA)2]

The aqueous solution behaviour of the equilibrium related cis-[PdCl₂(PTA)₂] and [PdCl(PTA)₃]Cl complexes has been investigated in the presence of acid and iodide ions. Several of the resulting species were identified and a reaction scheme accounting for identified complexes is proposed. The crystal structures of trans-[PdI₂(PTA-H)₂][PdI₃(PTA)]₂ · 2H₂O (1) (PTA-H⁺ = protonated form of PTA) and trans-[PdI₂(PTA)₂] (2) are reported. The geometry around the Pd(II) metal centre in 1 (for both the cation and anion) and 2 is distorted square planar. The PTA ligands occupy a trans orientation in the cation of 1 and in complex 2. Compound 1 represents a rare example of a Pd(II) system wherein the cation:anion pair, in a 1:2 ratio, are both coordination complexes. It is the first d⁸ Ni-triad square planar complex containing only one PTA ligand and only the second platinum group metal complex. For the cation in 1, the bond distances and angles are Pd(1)-P(1) = 2.2864(16) Å, Pd(1)-I(1) = 2.6216(7) Å, P(1)-Pd(1)-P(1)′ = 180.00(7)° and P(1)-Pd(1)-I(1) = 87.62(4)°, while in the anion the bond distances are Pd(2)-P(2) = 2.2377(15) Å, Pd(2)-I(4) = 2.5961(13) Å, Pd(2)-I(2) = 2.6328(13) Å, Pd(2)-I(3) = 2.6513(8) Å, while the angles are P(2)-Pd(2)-I(4) = 90.00(5)°, P(2)-Pd(2)-I(2) = 89.69(5)°, I(4)-Pd(2)-I(2) = 179.57(2)°, P(2)-Pd(2)-I(3) = 175.19(4)°, I(4)-Pd(2)-I(3) = 90.29(4)° and I(2)-Pd(2)-I(3) = 90.05(4)°. Bond distances and angles of the coordination polyhedron in 2 are Pd-P = 2.327(3) Å, Pd-I = 2.5916(10) Å, P-Pd-I = 89.13(7)° and P-Pd-P = 180.00(13)°. The average effective- and Tolman cone angles for the two ligands, calculated from the crystallographic data, are 115° and 117° for PTA and PTA-H, respectively.     

Microwave synthesis, spectroscopy, thermal analysis and crystal structure of an one-dimensional polymeric {[Cu(4,4′-bipy)(H2O)3(SO4)] · 2H2O}n complex

A metal organic-inorganic coordination framework formulated as {[Cu(4,4′-bipy)(H₂O)₃(SO₄)] · 2H₂O}_n (1) (where 4,4′-bipy = 4,4′-bipyridine) has been successfully prepared by microwave synthesis. The title complex has been characterized by single crystal X-ray crystallography, FT-IR spectroscopy and thermal analysis. Complex (1) is an one-dimensional (1D) polymer in which 4,4′-bipy acts as a bridging ligand supporting the formation of infinite [Cu(4,4′-bipy)(H₂O)₃(SO₄)] chains. The packing diagram shows that a 3D network is formed via hydrogen bonds. The infrared spectra and thermographic data are consistent with the chemical formula.     

Preparation and structural characterisation of the compound [MeC5H4NCOOH][ZnCl3(H2O)] · [MeC5H4NCOO]H2O

The reaction of the ZnCl₂ with 6-methyl-2-pyridinecarboxylic acid, with a 1:2 metal-to-ligand molar ratio, affords optimum yields for the synthesis of [MeC₅H₄NCOOH][ZnCl₃(H₂O)] · [MeC₅H₄NCOO]H₂O. The new complex has been characterised by elemental analyses, IR, ¹H and ¹³C{¹H} NMR, and single crystal X-ray diffraction methods. The X-ray structure analysis revealed that this structure consists of [ZnCl₃(H₂O)]⁻ anions, [MeC₅H₄NCOOH]⁺ cations, [MeC₅H₄NCOO] zwitterions, and solvent molecules (H₂O) by means of hydrogen bonds.     

Structures and excitation energies of ozone-water clusters O3(H2O)n (n = 1-4)

Hybrid density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations have been carried out for ozone-water clusters O₃(H₂O)_n (n = 1-4) in order to obtain hydration effects on the absorption spectrum of ozone. The first water molecule in n = 1 is bound to the ozone molecule by an oxygen orientation form in which the oxygen atom of H₂O orients the central oxygen atom of O₃. In n = 2, the water dimer is bound to O₃ and then the cyclic structure is formed as the most stable structure. For n = 3 (or n = 4), the cyclic water trimer (or tetramer) is bound by a hydrogen bond to the ozone molecule. The TD-DFT calculations of O₃(H₂O)_n (n = 0-4) show that the first and second excitation energies of O₃ are blue-shifted by the interaction with the water clusters. The magnitude of the spectral shift is largest in n = 2, and the shifts of the excitation energies are +0.07 eV for S₁ and +0.13 eV for S₂ states. In addition to the spectral shifts (S₁ and S₂ states), it is suggested that a charge-transfer band is appeared as a low-lying excited state above the S₁ and S₂ states. The origin of the spectrum shifts was discussed on the basis of theoretical results.     

Ln2(O2CCH2PO3)2(H2O)3 · H2O (Ln = La, Pr, Nd, Sm): Layered lanthanide phosphonoacetates containing two-dimensional -Ln-O- linkages

Four novel isostructural lanthanide phosphonate compounds with formula Ln₂(O₂CCH₂PO₃)₂(H₂O)₃ · H₂O [Ln = La (1), Pr (2), Nd (3), Sm (4)] have been prepared through hydrothermal reactions of phosphonoacetate acid and lanthanide nitrates. All show layered structures made up of {LnO₉} polyhedra and {CPO₃} tetrahedra with the lattice water molecules locating between the layers. Within the layer, chains of edge-sharing {LnO₉} polyhedra are connected via corner-sharing by phosphonate oxygens forming a two-dimensional -Ln-O- linkage. Thermal analyses and XRD measurements reveal that the framework structures can be maintained up to 400 °C.     

Photocatalytical decomposition of hydrazine in K4[Mo(CN)8] solution: X-ray crystal structure of (PPh4)2[Mo(CN)4O(NH3)] · 2H2O

Ligand-field photolysis of K₄[Mo(CN)₈] · 2H₂O in 98% N₂H₄ · H₂O yields the catalytical decomposition of N₂H₄ into NH₃ and N₂. From irradiated solutions of octacyanomolybdate(IV) both in NH₃(aq) and 98% N₂H₄ · H₂O(l) as solvents, the salt of the formula (PPh₄)₂[Mo(CN)₄O(NH₃)] · 2H₂O was isolated. The salt is not formed by direct ligand replacement in tetracyanooxomolybdate(IV) ions derived from K₃Na[Mo(CN)₄O₂] · 6H₂O as the solute in similar conditions. The X-ray crystal structure and spectral properties of (PPh₄)₂[Mo(CN)₄O(NH₃)] · 2H₂O are described. The improved method of the synthesis of K₄[Mo(CN)₈] · 2H₂O is also presented.     

Preparation and crystal structure of two novel cadmium (II)-trimesates, Cd(HTMA)(NC5H5)2 · 0.5CH3OH · 0.5DMF and Cd(HTMA) · 2H2O

Two novel complexes, Cd(HTMA)(NC₅H₅)₂ · 0.5CH₃OH · 0.5DMF (1) and Cd(HTMA) · 2H₂O (2), of cadmium (II)-trimesates are obtained from slow vapor diffusion and urea hydrolysis, respectively. The Cd(II) centers in the two complexes are bridged by three separate HTMA³⁻ ligands using a same coordination fashion, which contains one monodentate and two chelating bidentate carboxyl groups to form the herringbone-like motif. The herringbone-like motif is further interlinked to construct the two-dimensional Cd(II)-HTMA layer, which is stacked by mutual π-stacking of pyridines for 1 and by hydrogen bond of waters for 2. Thermal stabilities of the two complexes were investigated and the results indicated that Cd(II)-TMA layers in the two complexes are stable still upon 190 °C.     

Crystal structure, neutron vibrational spectroscopy, and DFT calculations of Li2B12H12 · 4H2O

The crystal structure of Li₂B₁₂H₁₂ · 4H₂O has been determined by X-ray powder diffraction and confirmed by a combination of neutron vibrational spectroscopy and first-principles calculations. The solvent-free analog of this compound (Li₂B₁₂H₁₂) has recently attracted interest as a putative intermediate in the decomposition of LiBH₄. Li₂B₁₂H₁₂ · 4H₂O appears in the initial stages of Li₂B₁₂H₁₂ synthesis from LiBH₄ and B₁₀H₁₄