Hydrothermal synthesis and structure of a Cu(I) bromide coordination polymer, [(tpyprz)3Cu10Br10] (tpyprz = tetra-2-pyridylpyrazine)

The hydrothermal reaction of CuBr₂ and tpyprz in the presence of NH₄VO₃ and HF for 72 h at 170 °C provided [(tpyprz)₃Cu₁₀Br₁₀] (1) in 20% yield. The two-dimensional structure of 1 may be described as Cu(I)-tpyprz chains, linked through {Cu₄Br₅}⁻ clusters in the ac-plane and decorated with {Cu₃Br₅}²⁻ clusters projecting from one face of the layer in the b-direction. The Cu(I) sites exhibit distorted trigonal coordination {CuBr₃} and distorted tetrahedral geometries, {CuBr₂N₂} and {CuN₄}. Crystal data for 1: monoclinic space group C2, a = 12.7561(8) Å, b = 19.359(1) Å, c = 15.860(1) Å, β = 97.178(1)°, V = 3885.8(4) Å³, Z = 2, D_calc = 2.222 g cm⁻³, μ(Mo Kα) = 78.75 cm⁻¹.     

A ferromagnetically coupled tetranuclear pseudo-cubane copper(II) cluster: magnetic and ESR studies

A tetranuclear copper(II) complex [Cu₄(NSI)₄] · 2C₂H₅OH · 2H₂O (NSI=hydroxethylsalicydeneimine) has been synthesized and characterized by X-ray diffraction analysis. The compound crystallizes in the monoclinic system, space group P2(1), a=9.494(3) Å, b=18.687(5) Å, c=13.149(4) Å, β=110.162(5)°, Z=2, R₁=0.0482 and wR₂=0.0978. The crystal structure contains a tetranuclear pseudo-cubane core based on an approximately cubane array of alternating copper and oxygen atoms. Each copper atom resides in a distorted square planar coordination environment with one nitrogen and three oxygen atoms from two NSI ligands. The tetranuclear units are linked in the crystal by O-H?O hydrogen bonds and weak Cu?O co-ordination bonds into one-dimensional structure. Variable temperature (5-300 K) magnetic measurements indicate the existence of ferromagnetic interactions among copper atoms. The IR and ESR spectra have also been investigated.     

Coordination modes of N-(2-hydroxyphenyl)methyl-bis-(2-pyridylmethyl)amine with copper (I) and (II) halides

The title ligand, N-(2-hydroxyphenyl)methyl-bis-(2-pyridylmethyl)amine, was prepared via a condensation-reduction synthetic route. The compounds, CuCl(C₁₉H₁₉N₃O) and [CuBr(C₁₉H₁₉N₃O)]⁺Br⁻ · 3H₂O, were readily synthesized from the reaction of CuCl or CuBr₂ and the ligand in acetonitrile. The title copper(I) compound is an O-H ? Cl hydrogen-bonded linear chain of tetrahedrally coordinated copper centers, and the title copper(II) compound exists as two strongly tetragonally distorted dibromide bridged metal cations in a dimer with the phenol hydroxyl groups weakly bound in a trans-fashion to one of the bridging bromides. In the copper(I) complex the phenoxy group acts only as a hydrogen bond donor, whereas in the copper(II) complex it acts both as a ligand and a hydrogen bond donor.     

Polymorphism and weak antiferromagnetic interactions in dibromo[(−)-sparteine-N,N]copper(II)

Two polymorphic crystal structures of the title compound, dibromo[(−)-sparteine-N,N^′]copper(II), 1, were determined. The structures of two isomorphs of 1, 1a [orthorhombic, P2₁2₁2₁, a=11.0463(9) Å, b=11.9839(15) Å and c=12.7835(19) Å] and 1b [orthorhombic, P2₁2₁2₁, a=7.6779(9) Å, b=12.0927(14) Å and c=18.090(2) Å], are composed of the same basic structural unit, Cu(C₁₅H₂₆N₂)Br₂. The bond distances in the molecular structures of 1a and 1b are identical to each other within the esds. However, there are slight differences in the bond angles around the Cu(II) center and considerable differences in their packing structure. Crystal 1a exhibits weak anti-ferromagnetism (J=−1.89 cm⁻¹) as opposed to the magnetically isolated paramagnetism observed for the analogous dichloro[(−)-sparteine]copper(II), 2. The results of a magneto-structural investigation of 1a and 2, and other supporting evidence, suggest that the pathway for the weak antiferromagnetic super-exchange in 1a might be through a Cu-Br ? Br-Cu contact.     

Synthesis, crystal structure, magnetic properties and electrochemical behaviour of the mixed valence compound [Cu(CN)3Cu(C3H10N2)2]

The binuclear mixed valence copper(I/II) compound [Cu^I(CN)₃Cu^II(tn)₂] (1) (tn = propane-1,3-diamine) and its acetonitrile adduct [Cu^I(CN)₃Cu^II(tn)₂] · 2MeCN (2) have been synthesized. Complex 1 crystallizes triclinic, space group , a = 8.117(2) Å, b = 8.389(2) Å, c = 11.920(2) Å, α = 108.728(3)°, β = 100.024(3)°, γ = 104.888(4)°, Z = 2, and compound 2 monoclinic, space group P2₁/m, a = 8.752(2) Å, b = 13.243(3) Å, c = 9.549(2) Å, β = 114.678(4)°, Z = 2. In both crystal structures, the binuclear [Cu^I(CN)₃Cu^II(tn)₂] complex with slightly different bonding geometries is formed. One of the three nitrogen atoms of a Cu^I(CN)₃ moiety is coordinated to Cu(II) at the apex of a square-pyramid with two chelating ligands tn on its base. The shortest intramolecular Cu^II?Cu^II distance in 1 is 5.640(7) Å. The EPR behaviour of 1 has been investigated at room temperature and at 77 K. The magnetic properties were measured in the temperature range 1.8-300 K.     

Synthesis, crystal structure, magnetic properties and EPR spectra of copper(II) acetate derivatives: tetra-(μ-acetato)bis(2-methylaminopyridine)copper(II) and catena-poly(aquadiacetato-μ-3-aminomethylpyridine)copper(II). Sheets formed by chains connected through hydrogen-bonds

The derivatives of Cu(OAc)₂ · H₂O with 2-methylaminopyridine and 3-aminomethylpyridine, [Cu₂(μ-OAc)₄(MeNHpy)₂] (1) and [Cu(OAc)₂(μ-NH₂CH₂py)(H₂O)]_n (2), respectively, have been synthesized and characterized. Compound 1 shows the dimer structure of [Cu₂(μ-OAc)₄(H₂O)₂], with four syn-syn bridging acetate groups and the MeNHpy ligand coordinated in the axial positions. It is antiferromagnetic (2J=−285 cm⁻¹). Signals of the triplet state are observed in its EPR spectrum and the zero-field splitting parameter has been calculated (D=0.36 cm⁻¹; g_∥=2.35; g_⊥=2.07). Otherwise, the ligand 3-aminomethylpyridine acts as bridging bidentate ligand in compound 2, forming infinite zig-zag chains. Each copper atom lies in a square-planar pyramidal coordination, determined by two nitrogen atoms of two bridge ligands, two oxygen atoms of two monodentate terminal acetate groups and a water molecule. The parallel chains form a sheet because of the hydrogen bonds between them. The shortest Cu-Cu distances are: 5.1270, 6.0952 and 6.2163 Å (inter-chains) and 7.875 Å (intra-chain). Compound 2 shows a slight antiferromagnetic effect below 30 K. The EPR spectra show an orthorhombic signal (g₁=2.26; g₂=2.08; g₃=2.06).     

Structures and magnetic properties of dicopper(II) and dinickel(II) complexes with end-on azido bridges

An asymmetric single EO azido bridged dinuclear copper(II) complex, [Cu₂(dmterpy)₂(μ-1,1-N₃)(N₃)₂] · NO₃ · (H₂O)₂1 [dmterpy = 5,5″-dimethyl-2,2′:6′,2″-terpyridine], and a double EO azido bridged dinuclear nickel(II) complex, [Ni₂(pbdiim)₄(μ-1,1-N₃)₂] · 2(N₃) · 6(H₂O) 2 [pbdiim = 2-(2′-pyridyl)benzo[1,2-d:4,5-d′]diimidazole], have been synthesized and characterized structurally and magnetically. Compound 1 consists of a single EO azido bridged Cu^II dimer in which each Cu^II ion is five-coordinated in the form of a distorted square-based pyramid. The N_(μ−1,1) atom holds on the apical position of one Cu^II pyramid with an elongated bond length of 2.305 Å and on the basal plane of another distorted Cu^II pyramid with a bond length of 1.991 Å. The Cu-N_(μ−1,1)-Cu angle is 117.4 (2)°. The copper(II) dimer forms a 1 D zig-zag chain via hydrogen bondings between azide ions, water molecules and the nitrate anion. Compound 2 consists of a double EO azido bridged Ni^II dimer with the Ni-N_(μ−1,1)-Ni bond angle of 102.96 (13)°. The coordination geometry of Ni^II is octahedral. Their magnetic properties have been measured in the range from 300 to 2 K and correlated with the molecular structures. Compound 1 shows weak ferromagnetic interactions within the copper(II) dimer (J = 2.88 cm⁻¹), despite the large EO azide bridge angle (117.4 (2)°). The intramolecular coupling between the Ni^II (S = 1) ions in compound 2 was found to be ferromagnetic (J = 27.87 cm⁻¹).     

Ferromagnetic trinuclear carbonato-bridged and tetranuclear hydroxo-bridged Cu(II) compounds with 4,4′-dimethyl-2,2′-bipyridine as ligand. X-ray structure, spectroscopy and magnetism

A controlled synthesis, characterisation and single-crystal X-ray analysis of two novel copper(II) compounds with the ligand 4,4′-dimethyl-2,2′-bipyridine (abbreviated dmbipy) is described. In a CO₂ atmosphere, with sodium hydroxide added, the carbonato-bridged triangular trinuclear compound [Cu₃(dmbipy)₆(μ₃-CO₃)](BF₄)₄(C₂H₅OH)(H₂O) (1) is obtained. Compound 1 crystallises in the monoclinic space group P2₁/n with a=16.169(6), b=23.351(11), c=21.312(7) Å, β=91.26(3), Z=4. The three copper ions are connected via the oxygen atoms from the symmetrically bridging carbonato group, resulting in a triangular array of copper atoms. Each copper has a distorted square-pyramidal environment with a basal plane formed by three nitrogen atoms of the two chelating bipyridine groups and the oxygen atom of the bridging carbonato group (Cu-N/O distances about 2.0 Å). The apical position at each copper is occupied by the fourth nitrogen atom of the bipyridines with distances varying from 2.100(11) to 2.146(11) Å. In all other experimental conditions the tetranuclear hydroxo-bridged compound [Cu₄(dmbipy)₄(μ₃-OH)₂(μ-OH)₂(H₂O)₂](BF₄)₄(H₂O)₄ (2) is obtained. Compound 2 crystallises in the monoclinic space group P2₁/c with a=13.274(8), b=21.685(7), c=11.266(7) Å, β=107.71(4), Z=2. The structure consists of two bis(hydroxo)-bridged dinuclear planar units which are connected with long Cu-O bonds to form a tetranuclear unit. Each Cu ion has a similar square-pyramidal coordination geometry: the equatorial plane of each Cu ion consists of two nitrogen atoms of the dmbipy ligand (Cu-N distances 1.945-2.003 Å), and two bridging hydroxo oxygen atoms (Cu-O distances 1.945-1.973 Å). The apical position of Cu1 is occupied by an oxygen atom of a water molecule with a distance of 2.262 Å. The second copper atom, Cu2, has the apical position occupied by an oxygen atom of a bridging hydroxo group at a distance of 2.349 Å; this bond is responsible for the formation of the tetranuclear unity. Compound 1 exhibits a ferromagnetic interaction between the copper ions with a J=29.3 cm⁻¹ and a very weak ferromagnetic intercluster interaction with zj′=2.4 cm⁻¹. Compound 2 also exhibits a ferromagnetic interaction between the copper ions with a J=31.1 cm⁻¹ and an overall magnetic interaction between the two dimeric units J′=8.76 cm⁻¹     

Complexation properties of a new macrocyclic polyaminic ligand (L) containing amidic pendant arms: crystal structure of [PbL](ClO4)2

Synthesis and characterisation of the new macrocyclic ligand 1,7-dimethyl-4,10-di(methylcarbamoylmethy)-1,4,7,10-tetraazacyclododecane (L) are reported. The ligand, based on cyclen (1,4,7,10-tetraazacyclododecane), has been functionalised by the insertion of two methyl groups and two amidic pendant arms linked to the amine nitrogens. The interaction of L with H⁺, Na(I), Ca(II), Cu(II), Zn(II), Pb(II), and Gd(III) ions has been studied by potentiometric titrations, microcalorimetric and ¹H NMR measurements in 0.1 mol dm⁻³ Me₄NCl aqueous solution at 298.1±0.1 K. The thermodynamic data suggest that the N₄ moiety is the binding site for Cu(II) and Zn(II), while in the case of Pb(II) also the pendant arms are coordinated to the metal ion. The crystal structure of [PbL](ClO₄)₂ (space group P2₁/a, a=12.883(2) Å, b=12.259(3) Å, c=17.275(5) Å, β=108.65(2)°, V=2585.0(11) ų, Z=4, R=0.0660, R_W ²=0.1467) shows the metal ion hexa-coordinated by the four nitrogen atoms of the cyclic tetra-amine and by the two amidic oxygens of the pendant arms.     

Hydrothermal syntheses and structures of a novel zincophosphite, [C6N2H18] · [Zn3(HPO3)4]

A novel three-dimensional organically templated zincophosphite, [C₆N₂H₁₈] · [Zn₃(HPO₃)₄], was synthesized under milder hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction, differential thermal-thermogravimetric analysis, powder X-ray diffraction, ³¹P MAS NMR spectrum, and IR spectroscopy. It crystallizes in the monoclinic system, space group C2/c with cell parameters: a = 8.7820(4) Å, b = 14.9417(7) Å, c = 15.4943(5) Å, β = 92.940(2)°, and Z = 4. The structure consists of a network of strictly alternating ZnO₄ tetrahedra and pseudo-pyramid, forming 4-membered ring chains. The structure has a 4.8.16-net and 8- and 16-membered ring channels where completely protonated N,N,N′,N′-tetramethylenediamine cations are encapsulated. The structure is stabilized by template-to-framework hydrogen bonding. In phosphites system, this compound possesses extra-large-pores.     

Effect of outer sphere anions on the structure and color of nitrosylpentaamminechromium complex

Three kinds of crystalline compounds containing the nitrosylpentaamminechromium complexes [Cr(NO)(NH₃)₅]²⁺(A) were obtained: chloride ACl₂ (red-orange), chloride perchlorate ACl(ClO₄) (brown), and perchlorate A(ClO₄)₂ (green). The cause of the color change of the complex A with the change of outer sphere anions was sought using X-ray structural data of ACl₂, ACl(ClO₄), and A(ClO₄)₂. Crystal data: ACl₂, orthorhombic, space group Cmcm, a=10.0236 (9) Å, b=9.098 (3) Å, c=10.357(1) Å, V=944.5 (5) ų, Z=4; ACl(ClO₄), tetragonal, space group P4/nmm, a=7.6986 (8) Å, c=9.9566(8) Å, V=590.1 (1) Å^3,Z=2; A(ClO₄)₂, orthorhombic, space group Pnma, a=15.760 (2) Å, b=11.480(2) Å, c=7.920 (2) Å, V=1432.9 (4) ų, Z=4. The complex cation in ACl₂ has a distorted octahedral structure with a linear CrNO moiety. The short CrN (nitrosyl) distance of 1.692 (7) Å indicates the presence of multiple bonding between the chromium atom and the nitrogen atom in the nitrosyl group. The interatomic distances and angles within the complex cations hardly change with the change of the counter anions, while the distances between the complex cations in each crystal increase in the order ACl₂<ACl(ClO₄)<A(ClO₄)₂. The bulky perchlorate anions seems to separate the complex cations, while smaller chloride anions are not large enough to separate them. The distance (3.213(5) Å) between O(NO) and N(NH₃ in the adjacent complex cation) is rather short in the crystal of ACl₂, and there are six hydrogen bonds, where the NO group is surrounded by four NH₃ ligands. The distance (4.002(5) Å) between O(NO) and N(NH₃) is much longer in the crystal of A(ClO₄)₂, indicating the presence of no hydrogen bonding. In the crystal of ACl(ClO₄) the distance (3.452(4) Å) between O(NO) and N(NH₃) is in between those of ACl₂ and A(ClO₄)₂. The presence of hydrogen bonding between O(NO) and N(NH₃ in the adjacent complex cation) seems to cause the color change with the change of outer sphere anions.     

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.     

Hydrothermal synthesis and characterization of a new inorganic-organic hybrid compound AMP[ZnCl3] (AMP = 2-aminomethylpyridinium)

A novel organic-inorganic hybrid complex [(2-NH₂CH₂C₅H₄N)ZnCl₃] has been hydrothermally synthesized and characterized by single crystal X-ray diffraction, thermal analysis and spectroscopic studies. The compound crystallizes in the triclinic system, space group , a = 7.5339(9), b = 7.589(2), c = 9.365(2) Å, α = 104.55(2)°, β = 97.22(1)°, γ = 87.88(2)°, V = 513.6(2), Z = 2. In the title compound the 2-aminomethylpyridine acts as a ligand covalently linked to Zn(II) cation to form a slightly distorted ZnCl₃N tetrahedral environment. Each [Zn(C₆H₈N₂)Cl₃] unit is connected to one neighbor by a pair of hydrogen bonds between the apical chlorides and amine hydrogen atoms and to the other by a couple of π-π stacking interactions between the aromatic rings of the coordinated ligands forming a novel one-dimensional chain-like arrangement. The title complex is the first one that contains both coordinated and hydrogen bonded 2-aminomethylpyridine. Solid state ¹³C and ¹⁵N CP-MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of carbons and nitrogen to the independent crystallographic sites. The Raman spectroscopy confirmed the presence of Zn-Cl and Zn-N bonds.     

Synthesis, characterisation and crystal structure of hydroxylamido-κN,O(iodo)[tris(3,5-dimethylpyrazol-1-yl)borato]nitrosylmolybdenum(II)

The unusual 18e seven-coordinate Mo(II) complex [Mo(NO)(H₂NO-κ²N,O)(Tp^Me2)I] (1; [Tp^Me2]⁻ is hydrotris(3,5-dimethylpyrazol-1-yl)borate) has been synthesised and characterised by IR, ¹H NMR and ESI-MS spectroscopies and by a single crystal X-ray diffraction study. The complex has a distorted pentagonal bipyramid structure with equatorial κ²-NH₂O⁻ ligand (d_N-O = 1.387 Å, d_Mo-N and d_Mo-O equal 2.049 and 2.092 Å, respectively). In the solid state 1 exists as a dimer (the point group C_i) due to the formation of two NH?O hydrogen bonds (d_N-H?O = 2.064 Å) between the adjacent NH₂O⁻ ligands, whilst in solution at/or above RT it resolves itself giving a monomer, which readily isomerises to more thermodynamically stable diastereoisomer.     

Macrocyclic dinuclear Zn(II) complexes: synthesis, structure and hydrolysis of tris(p-nitrophenyl) phosphate

A series of mono- and dinuclear zinc complexes of 3,6,9,17,20,23-hexaaza-29,30-dihydroxy-13,27-dimethyl-tricyclo[23,3,1^11,15]triaconta-1(28),11,13,15(30),25,26-hexaene (H₂L or BDBPH) have been defined in solution by potentiometry. The crystal structure of [Zn₂C₂₆H₄₀N₆O₂(CH₃OH)₂]·Br₂ has been determined by X-ray. Each zinc ion is coordinated to three nitrogen atoms, a bridged-phenolic oxygen atom, and a methanolic oxygen atom, which define a six-coordinated octahedron. Bond lengths of ZnN are in the range of 2.104(3)-2.120(3) Å and distances between Zn and O (bridged-phenolic oxygen) are 2.052(2), 2.062(2) Å, respectively. The dinuclear complexes: [Zn₂L]²⁺ and [Zn₂L(OH)]⁺ play crucial roles in hydrolytic reaction of tris(4-nitrophenyl)phosphate. A possible mechanism showed that [Zn₂L(OH)]⁺ acts as a nucleophile and [Zn₂L]²⁺ stabilizes the formation of the intermediate: [Zn₂L-BNP].     

Synthesis of copper(II) complexes with 3,5-bis(4,6-dimethylpyrimidin-2-yl)-4H-1,2,4-triazol-4-amine (L). Molecular and crystal structures of L and [Cu2L2Cl4]·2MeCN

A series of copper(II) complexes, i.e. Cu₂LCl₄, CuLCl₂·H₂O and [Cu₂L₂Cl₄]·2MeCN (8), based on a new potentially polytopic ligand, 3,5-bis(4,6-dimethylpyrimidin-2-yl)-4H-1,2,4-triazol-4-amine (3b, L), have been synthesized. The crystal structures of L and [Cu₂L₂Cl₄]·2MeCN were studied by X-ray single crystal analysis. The dinuclear compound [Cu₂L₂Cl₄]·2MeCN represents the first example of structurally characterized metal complexes with 3,5-di(pyrimidin-2-yl)-4H-1,2,4-triazol-4-amines. Both copper atoms have distorted tetragonal-pyramidal 3N + 2Cl environment. Surprisingly, in contrast to the complexes based on 3,5-di(pyridin-2-yl)-4H-1,2,4-triazol-4-amine (pyridinyl analog of L), the compound [Cu₂L₂Cl₄]·2MeCN adopts a dinuclear trans-(N′,N¹,N²)₂ double bridging binding mode which is due to tridentate coordination of two L molecules linking two copper atoms through N¹,N²-triazole and N′-pyrimidine atoms. It seems to be reasonable that it is methyl groups in pyrimidinyl moiety that obstruct the expected dinuclear (N′,N¹,N²,N″)₂ double bridging coordination being one of the most common for 4-substituted 3,5-di(pyridin-2-yl)-4H-1,2,4-triazoles and 3,5-di(pyridin-2-yl)-1,2,4-triazolates. Due to π-π stacking interactions, molecules of Cu₂L₂Cl₄ in the structure of [Cu₂L₂Cl₄]·2MeCN form 1D chains.     

Layered copper bromide coordination polymers from bis(pyridyl)piperazine-type precursors: Ligand dependent valence tuning and in situ hydrothermal reaction chemistry

Hydrothermal reaction of copper(II) bromide with either bis(4-pyridylmethyl)piperazine (bpmp) or bis(4-pyridylformyl)piperazine (bpfp) afforded layered coordination polymer solids. The racemic S,S and R,R stereochemistry dped ligands in [Cu₂Br₂(dped)]_n (1, dped = 1,2-di(4-pyridyl)ethanediol) were formed by the in situ transformation of bpmp via putative 4-pyridylmethanol intermediates, along with concomitant reduction to monovalent copper. The structure of 1 contains [Cu₂Br₂]_n chains comprising edge-shared [Cu₃Br₃] boat-conformation six-membered rings, linked into layer motifs by dped tethers with alternating stereochemistry. Lack of benzylic hydrogen atoms in bpfp causes that ligand to stay intact under the reaction conditions, generating the 2-D layered divalent copper phase [CuBr₂(bpfp)]_n (2).     

Synthesis, characterization, and magnetic properties of new binuclear CuCu bis(oxamato) complexes

Two new neutral, binuclear Cu^IICu^II bis(oxamato) complexes with the formula [Cu₂(opba)(pmdta)(MeOH)] · 1/2MeOH · dmf (3) and [Cu₂(nabo)(pmdta)(MeOH)] (4), with opba = o-phenylene-bis(oxamato), nabo = 2,3-naphthalene-bis(oxamato), pmdta = N,N,N′,N″,N″-pentamethyldiethylenetriamine and dmf = dimethylformamide have been synthesized and their crystal structures have been determined. The structure of 3 consists of dimeric [Cu₂(opba)(pmdta)(MeOH)] entities, joined together by mutual intermolecular Cu?O contacts of the Cu²⁺ ion of one [Cu(opba)]²⁻ complex fragment and one carboxylate atom of the oxamato group of a second [Cu(opba)]²⁻ complex fragment. The structure of 4 consists of neutral binuclear complexes joined together by hydrogen bonds and π-π interactions, giving rise to an unique supramolecular 1D-chain. The magnetic properties of 3 and 4 were studied by susceptibility measurements versus temperature. For the intramolecular J parameter, identical values of (−114 ± 2) cm⁻¹ (3) and (−112 ± 2) cm⁻¹ (4) were obtained.     

Unsupported intermolecular argentophilic interaction in the dimer of trinuclear silver(I) 3,5-diphenylpyrazolates

The reaction of a solution of sodium 3,5-diphenylpyrazolate, Na[Ph₂pz], with Ag(tht)NO₃ in dichloromethane affords thin needles of unsolvated and light-stable dimer of trimers [Ag₃(μ-3,5-Ph₂pz)₃]₂. The complex is characterized by X-ray crystallography and elemental analysis. The two trimers are rotated anti to each other. Three silver atoms bridged through exobidentate pyrazolate groups form a slightly puckered nine-membered ring with the shortest Ag?Ag intramolecular interaction in the metallocycle of 3.3571(8) Å. The other two silver centers are weakly interacting, Ag(3)?Ag(1) = 3.49 Å and Ag(3)?Ag(2) = 3.52 Å. The intermolecular interaction between the two trimers is Ag?Ag = 2.9712(14) Å. Packing diagram shows the dimer of trimer units are independent. Density Functional Theory calculations show that the M?M interaction is due to dispersion forces. [Ag₃(μ-3,5-Ph₂pz)₃]₂ crystallizes in the monoclinic space group C2/c with a = 22.169(4), b = 15.269(3), c = 22.482(5) Å, β = 103.69(3)° and V = 7394(3) ų.     

Synthesis of copper-zinc bimetallic imidazolate framework compounds and the structure of Cu(I)-containing Cu2Zn(N2C3H3)4

Copper(II)-zinc(II) bimetallic imidazolate metal-organic framework compounds of composition Cu_aZn_bIm_2(a + b) (Im = C₃H₃N₂), including Cu₂ZnIm₆ (1), were prepared in high yields from the metal oxides under mild aqueous conditions using a novel acid catalysis method. Mild acidic hydrothermal treatment of paramagnetic 1 (≥120 °C) gave diamagnetic Cu(I)-containing Cu₂ZnIm₄ (2) in high yield. The formation mechanism of 2 involves electron transfer from Im⁻ to Cu(II), with concomitant formation of the unusual cyclotriimidazole, C₉H₆N₆. Air-stable 2, characterized by single-crystal X-ray diffraction, crystallized in the tetragonal space group , with a = b = 10.9623(3), c = 6.3231(4) Å, α = β = γ = 90°, V = 759.86(6) Å³, and Z = 1.