Structural properties of trans‐cyclohexane‐1,2‐diamine complexes of copper(II) and zinc(II) acesulfamates

The title compounds, trans‐bis(trans‐cyclohexane‐1,2‐diamine)bis(6‐methyl‐2,2,4‐trioxo‐3,4‐dihydro‐1,2,3‐oxathiazin‐3‐ido)copper(II), [Cu(C₄H₄NO₄S)₂(C₆H₁₄N₂)₂], (I), and trans‐diaquabis(cyclohexane‐1,2‐diamine)zinc(II) 6‐methyl‐2,2,4‐trioxo‐3,4‐dihydro‐1,2,3‐oxathiazin‐3‐ide dihydrate, [Zn(C₆H₁₄N₂)₂(H₂O)₂](C₄H₄NO₄S)₂·2H₂O, (II), are two‐dimensional hydrogen‐bonded supramolecular complexes. In (I), the Cu^II ion resides on a centre of symmetry in a neutral complex, in a tetragonally distorted octahedral coordination environment comprising four amine N atoms from cyclohexane‐1,2‐diamine ligands and two N atoms of two acesulfamate ligands. Intermolecular N—H...O and C—H...O hydrogen bonds produce R₂²(12) motif rings which lead to two‐dimensional polymeric networks. In contrast, the Zn^II ion in (II) resides on a centre of symmetry in a complex dication with a less distorted octahedral coordination environment comprising four amine N atoms from cyclohexane‐1,2‐diamine ligands and two O atoms from aqua ligands. In (II), an extensive two‐dimensional network of N—H...O, O—H...O and C—H...O hydrogen bonds includes R₂¹(6) and R₄⁴(16) motif rings.     

Supramolecular architectures in metal(II) (Cd/Zn) halide/nitrate complexes of cytosine/5‐fluorocytosine

Three new metal(II)–cytosine (Cy)/5‐fluorocytosine (5FC) complexes, namely bis(4‐amino‐1,2‐dihydropyrimidin‐2‐one‐κN³)diiodidocadmium(II) or bis(cytosine)diiodidocadmium(II), [CdI₂(C₄H₅N₃O)₂], ( I ), bis(4‐amino‐1,2‐dihydropyrimidin‐2‐one‐κN³)bis(nitrato‐κ²O,O′)cadmium(II) or bis(cytosine)bis(nitrato)cadmium(II), [Cd(NO₃)₂(C₄H₅N₃O)₂], ( II ), and (6‐amino‐5‐fluoro‐1,2‐dihydropyrimidin‐2‐one‐κN³)aquadibromidozinc(II)–6‐amino‐5‐fluoro‐1,2‐dihydropyrimidin‐2‐one (1/1) or (6‐amino‐5‐fluorocytosine)aquadibromidozinc(II)–4‐amino‐5‐fluorocytosine (1/1), [ZnBr₂(C₄H₅FN₃O)(H₂O)]·C₄H₅FN₃O, ( III ), have been synthesized and characterized by single‐crystal X‐ray diffraction. In complex ( I ), the Cd^II ion is coordinated to two iodide ions and the endocyclic N atoms of the two cytosine molecules, leading to a distorted tetrahedral geometry. The structure is isotypic with [CdBr₂(C₄H₅N₃O)₂] [Muthiah et al. (2001). Acta Cryst. E 57 , m558–m560]. In compound ( II ), each of the two cytosine molecules coordinates to the Cd^II ion in a bidentate chelating mode via the endocyclic N atom and the O atom. Each of the two nitrate ions also coordinates in a bidentate chelating mode, forming a bicapped distorted octahedral geometry around cadmium. The typical interligand N—H…O hydrogen bond involving two cytosine molecules is also present. In compound ( III ), one zinc‐coordinated 5FC ligand is cocrystallized with another uncoordinated 5FC molecule. The Zn^II atom coordinates to the N(1) atom (systematic numbering) of 5FC, displacing the proton to the N(3) position. This N(3)—H tautomer of 5FC mimics N(3)‐protonated cytosine in forming a base pair (via three hydrogen bonds) with 5FC in the lattice, generating two fused R₂²(8) motifs. The distorted tetrahedral geometry around zinc is completed by two bromide ions and a water molecule. The coordinated and nonccordinated 5FCs are stacked over one another along the a‐axis direction, forming the rungs of a ladder motif, whereas Zn—Br bonds and N—H…Br hydrogen bonds form the rails of the ladder. The coordinated water molecules bridge the two types of 5FC molecules via O—H…O hydrogen bonds. The cytosine molecules are coordinated directly to the metal ion in each of the complexes and are hydrogen bonded to the bromide, iodide or nitrate ions. In compound ( III ), the uncoordinated 5FC molecule pairs with the coordinated 5FC ligand through three hydrogen bonds. The crystal structures are further stabilized by N—H…O, N—H…N, O—H…O, N—H…I and N—H…Br hydrogen bonds, and stacking interactions.     

Two nickel(II) bis[(pyridin‐2‐yl)methyl]amine complexes with homophthalic and benzene‐1,2,4,5‐tetracarboxylic acids

Two new Ni^II complexes involving the ancillary ligand bis[(pyridin‐2‐yl)methyl]amine (bpma) and two different carboxylate ligands, i.e. homophthalate [hph; systematic name: 2‐(2‐carboxylatophenyl)acetate] and benzene‐1,2,4,5‐tetracarboxylate (btc), namely catena‐poly[[aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)]‐μ‐2‐(2‐carboxylatophenyl)aceteto‐κ²O:O′], [Ni(C₉H₆O₄)(C₁₂H₁₃N₃)(H₂O)]_n, and (μ‐benzene‐1,2,4,5‐tetracarboxylato‐κ⁴O¹,O²:O⁴,O⁵)bis(aqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) bis(triaqua{bis[(pyridin‐2‐yl)methyl]amine‐κ³N,N′,N′′}nickel(II)) benzene‐1,2,4,5‐tetracarboxylate hexahydrate, [Ni₂(C₁₀H₂O₈)(C₁₂H₁₃N₃)₂(H₂O)₂]·[Ni(C₁₂H₁₃N₃)(H₂O)₃]₂(C₁₀H₂O₈)·6H₂O, (II), are presented. Compound (I) is a one‐dimensional polymer with hph acting as a bridging ligand and with the chains linked by weak C—H...O interactions. The structure of compound (II) is much more complex, with two independent Ni^II centres having different environments, one of them as part of centrosymmetric [Ni(bpma)(H₂O)]₂(btc) dinuclear complexes and the other in mononuclear [Ni(bpma)(H₂O)₃]²⁺ cations which (in a 2:1 ratio) provide charge balance for btc⁴⁻ anions. A profuse hydrogen‐bonding scheme, where both coordinated and crystal water molecules play a crucial role, provides the supramolecular linkage of the different groups.     

Two isomorphous ZnII/CoII complexes with tri‐tert‐butoxysilanethiol and histamine,and (4‐hydroxymethyl‐1H‐imidazole‐κN)bis(tri‐tert‐butoxysilanethiolato‐κ2O,S)zinc(II)

The complexes [2‐(1H‐imidazol‐4‐yl‐κN³)ethylamine‐κN]bis(tri‐tert‐butoxysilanethiolato‐κS)cobalt(II), [Co(C₁₂H₂₇O₃SSi)₂(C₅H₉N₃)], and [2‐(1H‐imidazol‐4‐yl‐κN³)ethylamine‐κN]bis(tri‐tert‐butoxysilanethiolato‐κS)zinc(II), [Zn(C₁₂H₂₇O₃SSi)₂(C₅H₉N₃)], are isomorphous. The central Zn^II/Co^II ions are surrounded by two S atoms from the tri‐tert‐butoxysilanethiolate ligand and by two N atoms from the chelating histamine ligand in a distorted tetrahedral geometry, with two intramolecular N—H...O hydrogen‐bonding interactions between the histamine NH₂ groups and tert‐butoxy O atoms. Molecules of the complexes are joined into dimers via two intermolecular bifurcated N—H...(S,O) hydrogen bonds. The Zn^II atom in [(1H‐imidazol‐4‐yl‐κN³)methanol]bis(tri‐tert‐butoxysilanethiolato‐κ²O,S)zinc(II), [Zn(C₁₂H₂₇O₃SSi)₂(C₄H₆N₂O)], is five‐coordinated by two O and two S atoms from the O,S‐chelating silanethiolate ligand and by one N atom from (1H‐imidazol‐4‐yl)methanol; the hydroxy group forms an intramolecular hydrogen bond with sulfur. Molecules of this complex pack as zigzag chains linked by N—H...O hydrogen bonds. These structures provide reference details for cysteine‐ and histidine‐ligated metal centers in proteins.     

Mononuclear and dinuclear bromide–nitrite cadmium(II) complexes with related 1,4‐diazabicyclo[2.2.2]octane ligands

The title compounds, di‐μ‐bromido‐bis[bromido(1‐carboxymethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane‐κN⁴)(nitrito‐κ²O,O′)cadmium(II)] dihydrate, [Cd₂Br₄(C₈H₁₅N₂O₂)₂(NO₂)₂]·2H₂O, (I), and aquabromido(1‐cyanomethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane‐κN⁴)bis(nitrito‐κ²O,O′)cadmium(II) monohydrate, [CdBr(C₈H₁₄N₃)(NO₂)₂(H₂O)]·H₂O, (II), are two‐dimensional hydrogen‐bonded metal–organic hybrid complexes. In (I), the complex is situated on a centre of inversion so that each symmetry‐related Cd^II atom is coordinated by two bridging Br atoms, one monodentate Br atom, one chelating nitrite ligand and one organic ligand, yielding a significantly distorted octahedral geometry. The combination of O—H...O and O—H...Br hydrogen bonds produces centrosymmetric R₆⁶(16) ring motifs, resulting in two‐dimensional layers parallel to the ab plane. In contrast, the complex molecule in (II) is mononuclear, with the Cd^II atom seven‐coordinated by two bidentate nitrite groups, one N atom from the organic ligand, one monodentate Br atom and a water O atom in a distorted pentagonal–bipyramidal environment. The combination of O—H...O and O—H...Br hydrogen bonds produces R₅⁴(14) and R₃³(8) rings which lead to two‐dimensional layers parallel to the ac plane.     

Synthesis,crystal structures and luminescence properties of seven mononuclear zinc(II), cadmium(II), cobalt(II) and nickel(II) complexes with 5‐(4‐methylphenyl)‐3‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazole

Due to their versatile coordination modes and metal‐binding conformations, triazolyl ligands can provide a wide range of possibilities for the construction of supramolecular structures. Seven mononuclear transition metal complexes with different structural forms, namely aquabis[3‐(4‐methylphenyl)‐5‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazolato‐κ²N ¹,N ⁵]zinc(II), [Zn(C₁₄H₁₁N₄)₂(H₂O)], (I), bis[5‐(4‐methylphenyl)‐3‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazole‐κ²N ³,N ⁴]bis(nitrato‐κO )zinc(II), [Zn(NO₃)₂(C₁₄H₁₂N₄)₂], (II), bis(methanol‐κO )bis[3‐(4‐methylphenyl)‐5‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazolato‐κ²N ¹,N ⁵]zinc(II), [Zn(C₁₄H₁₁N₄)₂(CH₄O)₂], (III), diiodidobis[5‐(4‐methylphenyl)‐3‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazole‐κ²N ³,N ⁴]cadmium(II), [CdI₂(C₁₄H₁₂N₄)₂], (IV), bis[5‐(4‐methylphenyl)‐3‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazole‐κ²N ³,N ⁴]bis(nitrato‐κO )cadmium(II), [Cd(NO₃)₂(C₁₄H₁₂N₄)₂], (V), aquabis[3‐(4‐methylphenyl)‐5‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazolato‐κ²N ¹,N ⁵]cobalt(II), [Co(C₁₄H₁₁N₄)₂(H₂O)], (VI), and diaquabis[3‐(4‐methylphenyl)‐5‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazolato‐κ²N ¹,N ⁵]nickel(II), [Ni(C₁₄H₁₁N₄)₂(H₂O)₂], (VII), have been prepared by the reaction of transition metal salts (Zn^II, Cd^II, Co^II and Ni^II) with 3‐(4‐methylphenyl)‐5‐(pyridin‐2‐yl)‐1H‐1,2,4‐triazole (pymphtzH) under either ambient or hydrothermal conditions. These compounds have been characterized by elemental analysis, IR spectroscopy and single‐crystal X‐ray diffraction. All the complexes form three‐dimensional supramolecular structures through hydrogen bonds or through π–π stacking interactions between the centroids of the pyridyl or arene rings. The pymphtzH and pymphtz⁻ entities act as bidentate coordinating ligands in each structure. Moreover, all the pyridyl N atoms are coordinated to metal atoms (Zn, Cd, Co or Ni). The N atom in the 4‐position of the triazole group is coordinated to the Zn and Cd atoms in the crystal structures of (II), (IV) and (V), while the N atom in the 1‐position of the triazolate group is coordinated to the Zn, Co and Ni atoms in (I), (III), (VI) and (VII).     

Copper(II) bromide and copper(II) acetate complexes of 4,4′‐(p‐phenylene)bipyridazine

4,4′‐(p‐Phenylene)bipyridazine, C₁₄H₁₀N₄, (I), and the coordination compounds catena‐poly[[dibromidocopper(II)]‐μ‐4,4′‐(p‐phenylene)bipyridazine‐κ²N²:N^2′], [CuBr₂(C₁₄H₁₀N₄)]_n, (II), and catena‐poly[[[tetrakis(μ‐acetato‐κ²O:O′)dicopper(II)]‐μ‐4,4′‐(p‐phenylene)bipyridazine‐κ²N¹:N^1′] chloroform disolvate], {[Cu₂(C₂H₃O₂)₄(C₁₄H₁₀N₄)]·2CHCl₃}_n, (III), contain a new extended bitopic ligand. The combination of the p‐phenylene spacer and the electron‐deficient pyridazine rings precludes C—H...π interactions between the lengthy aromatic molecules, which could be suited for the synthesis of open‐framework coordination polymers. In (I), the molecules are situated across a center of inversion and display a set of very weak intermolecular C—H...N hydrogen bonds [3.399 (3) and 3.608 (2) Å]. In (II) and (III), the ligand molecules are situated across a center of inversion and act as N²,N^2′‐bidentate [in (II)] and N¹,N^1′‐bidentate [in (III)] long‐distance bridges between the metal ions, leading to the formation of coordination chains [Cu—N = 2.005 (3) Å in (II) and 2.199 (2) Å in (III)]. In (II), the copper ion lies on a center of inversion and adopts CuN₂Br₄ (4+2)‐coordination involving two long axial Cu—Br bonds [3.2421 (4) Å]. In (III), the copper ion has a tetragonal pyramidal CuO₄N environment. The uncoordinated pyridazine N atom and two acetate O atoms provide a multiple acceptor site for accommodation of a chloroform solvent molecule by trifurcated hydrogen bonding [C—H...O(N) = 3.298 (5)–3.541 (4) Å].     

catena‐Poly[copper(II)‐di‐μ‐acetylacetonato‐copper(II)‐bis(μ‐4‐hydroxy‐3‐methoxybenzaldehyde picoloylhydrazonato)] and (acetylacetonato)(4‐methoxybenzaldehyde picoloylhydrazonato)copper(II)

In the two title copper(II) complexes, [CuL(C₅H₇O₂)]_n, (I), and [CuL′(C₅H₇O₂)], (II), respectively, where HL is 4‐hydroxy‐3‐methoxybenzaldehyde picoloylhydrazone, C₁₄H₁₂N₃O₃, and HL′ is 4‐methoxybenzaldehyde picoloylhydrazone, C₁₄H₁₂N₃O₂, the Cu^II ions display a highly Jahn–Teller‐distorted octahedral and a square‐planar coordination geometry, respectively. In complex (I), two neighbouring Cu^II atoms are bridged by L⁻ and acetylacetonate, alternately, giving rise to a one‐dimensional chain of CuN₂O₄ octahedra interconnected by these two ligands along the a axis. In addition, the hydroxy H atom of the vanillin group connects to the carboxyl O atom of the adjacent chain via an O—H...O hydrogen bond, giving rise to a three‐dimensional supramolecular assembly. Complex (II) displays a discrete structure.     

Cobalt(II) and nickel(II) complexes of quinoline‐2‐carboxyl­ate

The title complexes, trans‐di­aqua­bis­(quinoline‐2‐carboxyl­ato‐κ²N,O)­cobalt(II)–water–methanol (1/2/2), [Co(C₁₀H₆NO₂)₂(H₂O)₂]·2CH₄O·2H₂O, and trans‐di­aqua­bis­(quinoline‐2‐car­box­yl­ato‐κ²N,O)­nickel(II)–water–methanol (1/2/2), [Ni(C₁₀H₆NO₂)₂(H₂O)₂]·2CH₄O·2H₂O, are isomorphous and contain Co^II and Ni^II ions at centers of inversion. Both complexes have the same distorted octahedral coordination geometry, and each metal ion is coordinated by two quinoline N atoms, two carboxyl­ate O atoms and two water O atoms. The quinoline‐2‐carboxyl­ate ligands lie in trans positions with respect to one another, forming the equatorial plane, with the two water ligands occupying the axial positions. The complex mol­ecules are linked together by hydrogen bonding involving a series of ring patterns which include the uncoordinated water and methanol mol­ecules.     

Supramolecular architectures in CoII and CuII complexes with thiophene‐2‐carboxylate and 2‐amino‐4,6‐dimethoxypyrimidine ligands

The coordination chemistry of mixed‐ligand complexes continues to be an active area of research since these compounds have a wide range of applications. Many coordination polymers and metal–organic framworks are emerging as novel functional materials. Aminopyrimidine and its derivatives are flexible ligands with versatile binding and coordination modes which have been proven to be useful in the construction of organic–inorganic hybrid materials and coordination polymers. Thiophenecarboxylic acid, its derivatives and their complexes exhibit pharmacological properties. Cobalt(II) and copper(II) complexes of thiophenecarboxylate have many biological applications, for example, as antifungal and antitumor agents. Two new cobalt(II) and copper(II) complexes incorporating thiophene‐2‐carboxylate (2‐TPC) and 2‐amino‐4,6‐dimethoxypyrimidine (OMP) ligands have been synthesized and characterized by X‐ray diffraction studies, namely (2‐amino‐4,6‐dimethoxypyrimidine‐κN)aquachlorido(thiophene‐2‐carboxylato‐κO)cobalt(II) monohydrate, [Co(C₅H₃O₂S)Cl(C₆H₉N₃O₂)(H₂O)]·H₂O, (I), and catena‐poly[copper(II)‐tetrakis(μ‐thiophene‐2‐carboxylato‐κ²O:O′)‐copper(II)‐(μ‐2‐amino‐4,6‐dimethoxypyrimidine‐κ²N¹:N³)], [Cu₂(C₅H₃O₂S)₄(C₆H₉N₃O₂)]_n, (II). In (I), the Co^II ion has a distorted tetrahedral coordination environment involving one O atom from a monodentate 2‐TPC ligand, one N atom from an OMP ligand, one chloride ligand and one O atom of a water molecule. An additional water molecule is present in the asymmetric unit. The amino group of the coordinated OMP molecule and the coordinated carboxylate O atom of the 2‐TPC ligand form an interligand N—H…O hydrogen bond, generating an S(6) ring motif. The pyrimidine molecules also form a base pair [R₂²(8) motif] via a pair of N—H…N hydrogen bonds. These interactions, together with O—H…O and O—H…Cl hydrogen bonds and π–π stacking interactions, generate a three‐dimensional supramolecular architecture. The one‐dimensional coordination polymer (II) contains the classical paddle‐wheel [Cu₂(CH₃COO)₄(H₂O)₂] unit, where each carboxylate group of four 2‐TPC ligands bridges two square‐pyramidally coordinated Cu^II ions and the apically coordinated OMP ligands bridge the dinuclear copper units. Each dinuclear copper unit has a crystallographic inversion centre, whereas the bridging OMP ligand has crystallographic twofold symmetry. The one‐dimensional polymeric chains self‐assemble via N—H…O, π–π and C—H…π interactions, generating a three‐dimensional supramolecular architecture.     

The hydrogen‐bonded dimers of N,N′,N′′‐tricyclohexylphosphoric triamide in new tin(IV) and copper(II) complexes

In the new tin(IV) and copper(II) complexes, cis‐dichlorido‐trans‐dimethyl‐cis‐bis(N,N′,N′′‐tricyclohexylphosphoric triamide‐κO)tin(IV), [Sn(CH₃)₂Cl₂(C₁₈H₃₆N₃OP)₂], (I), and trans‐diaquabis(N,N′,N′′‐tricyclohexylphosphoric triamide‐κO)copper(II) dinitrate–N,N′,N′′‐tricyclohexylphosphoric triamide (1/2), [Cu(C₁₈H₃₆N₃OP)₂(H₂O)₂](NO₃)₂·2C₁₈H₃₆N₃OP, (II), the N,N′,N′′‐tricyclohexylphosphoric triamide (PTA) ligands exist as hydrogen‐bonded dimers via P=O...H—N interactions around the metal center. The asymmetric unit in (I) consists of one complete complex molecule located on a general position. The Sn^IV coordination geometry is octahedral with two cis hydrogen‐bonded PTA ligands, two cis chloride ligands and two trans methyl groups. The asymmetric unit in (II) contains one half of a [Cu(PTA)₂(H₂O)₂]²⁺ dication on a special position (site symmetry for the Cu atom), one nitrate anion and one free PTA molecule, both on general positions. The complex adopts a square‐planar trans‐[CuO₂O₂] coordination geometry, with the Cu^II ion coordinated by two PTA ligands and two water molecules. Each of the noncoordinated PTA molecules is hydrogen bonded to a neighboring coordinated PTA molecule and an adjacent water molecule; the phosphoryl O atom acts as a double‐H‐atom acceptor. The P atoms in the PTA ligands of both complexes and in the noncoordinated hydrogen‐bonded molecules in (II) adopt a slightly distorted tetrahedral environment.     

Transition metal complexes with pyrazole‐derived ligands. XI. [Zn(μ‐L)(HL)(OAc)]2 (HL is 4‐acetyl‐3‐amino‐5‐methyl­pyrazole)

The title compound, bis(μ‐4‐acetyl‐3‐amino‐5‐methyl­pyrazol­ato‐N¹:N²)­bis­[(acetato‐O)­(4‐acetyl‐3‐amino‐5‐methyl­pyraz­ole‐N²)­zinc(II)], [Zn₂(C₆H₈N₃O)₂(C₂H₃O₂)₂(C₆H₉N₃O)₂], ex‐ists as a centrosymmetric binuclear mol­ecule with two tetrahedrally coordinated Zn atoms bridged by two pyrazolate anions. The geometry of the terminal and bridging pyrazole ligands are slightly different as a consequence of their differing modes of coordination.     

Zinc(II) and cadmium(II) chloride complexes with 4,4′‐bi‐1,2,4‐triazole

New coordination compounds with the 4,4′‐bi‐1,2,4‐triazole ligand (btr), namely tetraaqua‐2κ⁴O‐di‐μ₂‐4,4′‐bi‐1,2,4‐triazole‐1:2κ²N¹:N^1′;2:3κ²N¹:N^1′‐hexachlorido‐1κ³Cl,3κ³Cl‐trizinc(II), [Zn₃Cl₆(C₄H₄N₆)₂(H₂O)₄], (I), and poly[cadmium(II)‐μ₂‐4,4′‐bi‐1,2,4‐triazole‐κ²N¹:N²‐di‐μ₂‐chlorido], [CdCl₂(C₄H₄N₆)]_n, (II), reveal an unprecedented molecular zwitterionic structure for (I) and a polymeric two‐dimensional layer structure for (II). Differences between these products, which involve the formation of either charge‐separated chlorometallate/aquametal fragments or complementary organic and inorganic bridges, are attributable to the hardness–softness characters of the metal cations. In (I), two N¹,N^1′‐bidentate btr molecules connect one [Zn(H₂O)₄]²⁺ cation and two [ZnCl₃]⁻ anions into a linear trizinc motif (the Zn atom of the cation occupies a centre of inversion in an N₂O₄ coordination octahedron, whereas the Zn atom of the anion possesses a distorted tetrahedral Cl₃N environment). In (II), the distorted vertex‐sharing CdCl₄N₂ octahedra are linked into binuclear [Cd₂(μ₂‐Cl)(μ₂‐btr)₂]³⁺ fragments by unprecedented N¹:N²‐bidentate btr double bridges and bridging chloride ligands, while the additional chloride anions are also bridging, providing further propagation of the fragments into a two‐dimensional network [Cd—Cl = 2.5869 (2)–2.6248 (7) Å].     

Two new dimeric cadmium(II) and zinc(II) sulfate complexes with 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine and 2,2:6′,2′′‐ter­pyridine

The structures of two new sulfate complexes are reported, namely di‐μ‐sulfato‐κ³O,O′:O′′‐bis{aqua­[2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine‐κ³N¹,N²,N⁶]­cadmium(II)} tetra­hydrate, [Cd₂(SO₄)₂(C₁₆H₁₂N₆)₂(H₂O)₂]·4H₂O, and di‐μ‐sulfato‐κ²O:O′‐bis­[(2,2′:6′,2′′‐ter­pyridine‐κ³N¹,N^1′,N^1′′)­zinc(II)] dihydrate, [Cd₂(SO₄)₂(C₁₅H₁₁N₃)₂]·2H₂O, the former being the first report of a Cd(tpt) complex [tpt is 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine]. Both compounds crystallize in the space group P and form centrosymmetric dimeric structures. In the cadmium complex, the metal center is heptacoordinated in the form of a pentagonal bipyramid, while in the zinc complex, the metal ion is in a fivefold environment, the coordination geometry being intermediate between square pyramidal and trigonal bipyramidal. Packing of the dimers leads to the formation of planar structures strongly linked by hydrogen bonding.     

Adducts of bis(acetylacetonato)zinc(II) with 1,10‐phenanthroline and 2,2′‐bipyridine

In each of the zinc(II) complexes bis(acetylacetonato‐κ²O,O′)(1,10‐phenanthroline‐κ²N,N′)zinc(II), [Zn(C₅H₇O₂)₂(C₁₂H₈N₂)], (I), and bis(acetylacetonato‐κ²O,O′)(2,2′‐bipyridine‐κ²N,N′)zinc(II), [Zn(C₅H₇O₂)₂(C₁₀H₈N₂)], (II), the metal center has a distorted octahedral coordination geometry. Compound (I) has crystallographically imposed twofold symmetry, with Z′ = 0.5. The presence of a rigid phenanthroline group precludes intramolecular hydrogen bonding, whereas the rather flexible bipyridyl ligand is twisted to form an intramolecular C—H...O interaction [the chelated bipyridyl ligand is nonplanar, with the pyridyl rings inclined at an angle of 13.4 (1)°]. The two metal complexes are linked by dissimilar C—H...O interactions into one‐dimensional chains. The present study demonstrates the distinct effects of two commonly used ligands, viz. 1,10‐phenanthroline and 2,2′‐bipyridine, on the structures of metal complexes and their assembly.     

Structure and Magnetic Properties of Mononuclear Copper(II) Complexes with 2,2‐Bipyrimidine, 2,3‐Bis(2‐pyridyl)pyrazine,and 4‐Terpyridone Based Ligands

Four new complexes of [Cu(bpm)(ox)(H₂O)] ( 1 ), [Cu(tpd)(dca)(H₂O)] ( 2 ), [Cu(bppz)(N₃)₂] ( 3 ), and [Cu(bpm)₂(μ_1,3‐N₃)(N₃)] ( 4 ) (bpm = 2,2′‐bipyrimidine, bppz = 2,3‐bis(2‐pyridyl)pyrazine, tpd = 4‐terpyridone, dca = dicyanamide, ox = oxalate) have been prepared and characterized by X‐ray single‐crystal analysis and variable‐temperature magnetic measurements. Compounds 1–4 are essentially mononuclear Cu(II) complexes. However, in complex 1 , Cu(II) it was found that intermolecular hydrogen bonding through between H₂O and ox formed 1‐D chain structure. In complex 2 it was found that the hydrogen bonding between H₂O and tpd of the next molecule led to for a binuclear Cu(II) complex. In complex 3 , two nitrogen atoms, one of the pyridyl group of bppz and one of N₃^? ligands, are weakly coordinated to neighbor Cu(II) ion thus leading to formation of a 1‐D chain structure. In complex 4 , one nitrogen atom of terminated N₃^? is weakly coordinated to the neighbor Cu(II) site to form a 1‐D polymeric structure. The magnetic susceptibility measurements indicate that complex 1 and 4 exhibit a weak antiferromagnetic interaction whereas a ferromagnetic coupling has been established for complexes 2 and 3 .     

Cobalt(II), nickel(II) and copper(II) complexes of iso­quinoline‐3‐carbox­ylate

The crystal structures of the title complexes, namely trans‐bis­(iso­quinoline‐3‐carboxyl­ato‐κ²N,O)­bis­(methanol‐κO)cobalt(II), [Co(C₁₀H₆NO₂)₂(CH₃OH)₂], and the corresponding nickel(II) and copper(II) complexes, [Ni(C₁₀H₆NO₂)₂(CH₃OH)₂] and [Cu(C₁₀H₆NO₂)₂(CH₃OH)₂], are isomorphous and contain metal ions at centres of inversion. The three compounds have the same distorted octahedral coordination geometry, and each metal ion is bonded by two quinoline N atoms, two carboxyl­ate O atoms and two methanol O atoms. Two iso­quinoline‐3‐carboxyl­ate ligands lie in trans positions, forming the equatorial plane, and the two methanol ligands occupy the axial positions. The complex mol­ecules are linked together by O—H⋯O hydrogen bonds between the methanol ligands and neighbouring carboxyl­ate groups.     

Complexes of nickel(II) and copper(II) with 1,2,4‐triazole‐3‐carboxylic acid and of cobalt(III) with 3‐amino‐1,2,4‐triazole‐5‐carboxylic acid

Because of their versatile coordination modes and strong coordination ability for metals, triazole ligands can provide a wide range of possibilities for the construction of metal–organic frameworks. Three transition‐metal complexes, namely bis(μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato)‐κ³N ²,O :N ¹;κ³N ¹:N ²,O‐bis[triamminenickel(II)] tetrahydrate, [Ni₂(C₃HN₃O₂)₂(NH₃)₆]·4H₂O, (I), catena‐poly[[[diamminediaquacopper(II)]‐μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato‐κ³N ¹:N ⁴,O‐[diamminecopper(II)]‐μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato‐κ³N ⁴,O :N ¹] dihydrate], {[Cu₂(C₃HN₃O₂)₂(NH₃)₄(H₂O)₂]·2H₂O}_n , (II), (μ‐5‐amino‐1,2,4‐triazol‐1‐ide‐3‐carboxylato‐κ²N ¹:N ²)di‐μ‐hydroxido‐κ⁴O :O‐bis[triamminecobalt(III)] nitrate hydroxide trihydrate, [Co₂(C₃H₂N₄O₂)(OH)₂(NH₃)₆](NO₃)(OH)·3H₂O, (III), with different structural forms have been prepared by the reaction of transition metal salts, i.e. NiCl₂, CuCl₂ and Co(NO₃)₂, with 1,2,4‐triazole‐3‐carboxylic acid or 3‐amino‐1,2,4‐triazole‐5‐carboxylic acid hemihydrate in aqueous ammonia at room temperature. Compound (I) is a dinuclear complex. Extensive O—H…O, O—H…N and N—H…O hydrogen bonds and π–π stacking interactions between the centroids of the triazole rings contribute to the formation of the three‐dimensional supramolecular structure. Compound (II) exhibits a one‐dimensional chain structure, with O—H…O hydrogen bonds and weak O—H…N, N—H…O and C—H…O hydrogen bonds linking anions and lattice water molecules into the three‐dimensional supramolecular structure. Compared with compound (I), compound (III) is a structurally different dinuclear complex. Extensive N—H…O, N—H…N, O—H…N and O—H…O hydrogen bonding occurs in the structure, leading to the formation of the three‐dimensional supramolecular structure.     

Two new cadmium(II) coordination polymers based on bis(1,2,4‐triazol‐1‐yl)alkane ligands and pyrazine‐2,3‐dicarboxylic acid

Assemblies of pyrazine‐2,3‐dicarboxylic acid and Cd^II in the presence of bis(1,2,4‐triazol‐1‐yl)butane or bis(1,2,4‐triazol‐1‐yl)ethane under ambient conditions yielded two new coordination polymers, namely poly[[tetraaqua[μ₂‐1,4‐bis(1,2,4‐triazol‐1‐yl)butane‐κ²N⁴:N^4′]bis(μ₂‐pyrazine‐2,3‐dicarboxylato‐κ³N¹,O²:O³)dicadmium(II)] dihydrate], {[Cd₂(C₆H₂N₂O₄)₂(C₈H₁₂N₆)(H₂O)₄]·2H₂O}_n, (I), and poly[[diaqua[μ₂‐1,2‐bis(1,2,4‐triazol‐1‐yl)ethane‐κ²N⁴:N^4′]bis(μ₃‐pyrazine‐2,3‐dicarboxylato‐κ⁴N¹,O²:O³:O^3′)dicadmium(II)] dihydrate], {[Cd₂(C₆H₂N₂O₄)₂(C₆H₈N₆)(H₂O)₂]·2H₂O}_n, (II). Complex (I) displays an interesting two‐dimensional wave‐like structure and forms a distinct extended three‐dimensional supramolecular structure with the help of O—H...N and O—H...O hydrogen bonds. Complex (II) has a three‐dimensional framework structure in which hydrogen bonds of the O—H...N and O—H...O types are found.     

Copper(II) and Cadmium(II) Complexes Based on N,N‐Bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine Ligand: Syntheses,Structures, Magnetic,and Luminescent Properties

The reaction of the aryl‐oxide ligand H₂L [H₂L = N,N‐bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine] with CuSO₄ · 5H₂O, CuCl₂ · 2H₂O, CuBr₂, CdCl₂ · 2.5H₂O, and Cd(OAc)₂ · 2H₂O, respectively, under hydrothermal conditions gave the complexes [Cu(H₂L¹)₂] · SO₄ · 3CH₃OH ( 1 ), [Cu₂(H₂L²)₂Cl₄] ( 2 ), [Cu₂(H₂L²)₂Br₄] ( 3 ), [Cd₂(HL)₂Cl₂] ( 4 ), and [Cd₂(L)₂(CH₃COOH)₂] · H₂L ( 5 ), where H₂L¹ [H₂L¹ = 2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenol] and H₂L² [H₂L² = 2‐(2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenoxy)‐4, 6‐dimethylphenol] were derived from the solvothermal in situ metal/ligand reactions. These complexes were characterized by IR spectroscopy, elementary analysis, and X‐ray diffraction. A low‐temperature magnetic susceptibility measurement for the solid sample of 2 revealed antiferromagnetic interactions between two central copper(II) atoms. The emission property studies for complexes 4 and 5 indicated strong luminescence emission.