A dihydroxidotetracopper(II) framework supported by 4,4′‐(adamantane‐1,3‐diyl)bis(1,2,4‐triazole) and benzene‐1,3,5‐tricarboxylate bridges

The new bifunctional ligand 4,4′‐(adamantane‐1,3‐diyl)bis(1,2,4‐triazole) (tr₂ad) and benzene‐1,3,5‐tricarboxylate sustain complementary coordination bridging for the three‐dimensional framework of poly[[bis[μ₃‐4,4′‐(adamantane‐1,3‐diyl)bis(1,2,4‐triazole)‐κ³N¹:N²:N^1′]bis(μ₄‐benzene‐1,3,5‐tricarboxylato‐κ⁴O¹:O^1′:O³:O⁵)di‐μ₃‐hydroxido‐κ⁶O:O:O‐tetracopper(II)] dihydrate], {[Cu₄(C₉H₃O₆)₂(OH)₂(C₁₄H₁₈N₆)₂]·2H₂O}_n. The net node is a centrosymmetric (μ₃‐OH)₂Cu₄ cluster [Cu—O = 1.9525 (14)–2.0770 (15) Å and Cu...Cu = 3.0536 (5) Å] involving two independent copper ions in tetragonal pyramidal CuO₄N and trigonal bipyramidal CuO₃N₂ environments. One carboxylate group of the anion is bridging and the other two are monodentate, leading to the connection of three hydroxide clusters and the generation of neutral coordination layers separated by 9.3583 (5) Å. The interlayer linkage is effected by μ₃‐tr₂ad ligands, with one triazole group N¹:N²‐bridging and the second monodentate [Cu—N = 1.9893 (19), 2.010 (2) and 2.411 (2) Å]. In total, the hydroxide clusters are linked to six close neighbors within the carboxylate layer and to four neighbors via tr₂ad bridges. Hydrogen bonding of solvent water molecules to noncoordinated triazole N atoms and carboxylate groups provides two additional links for the net, which adopts a 12‐connected topology corresponding to hexagonal closest packing. The study also introduces a new type of bis(triazole) ligand, which may find wider applications for supramolecular synthesis.     

Ionothermal synthesis and crystal structure of a new organic–inorganic hybrid compound: catena‐poly[bis(1‐ethyl‐3‐methylimidazolium) [hepta‐μ‐bromido‐pentacuprate(I)]]

A new organic–inorganic hybrid compound, catena‐poly[bis(1‐ethyl‐3‐methylimidazolium) [μ₅‐bromido‐tri‐μ₃‐bromido‐tri‐μ₂‐bromido‐pentacuprate(I)]], {(C₆H₁₁N₂)₂[Cu₅Br₇]}_n, has been obtained under ionothermal conditions from a reaction mixture containing Ba(OH)₂·8H₂O, Cu(OH)₂·2H₂O, As₂O₅, 1‐ethyl‐3‐methylimidazolium bromide and distilled water. The crystal structure consists of complex [Cu₅Br₇]²⁻ anions arranged in sinusoidal {[Cu₅Br₇]²⁻}_n chains running along the a axis, which are surrounded by 1‐ethyl‐3‐methylimidazolium cations. Three of the five unique Br atoms and one of the three Cu^I atoms occupy special positions with half‐occupancy (a mirror plane perpendicular to the b axis, site symmetry m). The Cu^I ions are in a distorted tetrahedral coordination environment, with four Br atoms at distances ranging from 2.3667 (10) to 2.6197 (13) Å, and an outlier at 3.0283 (12) Å, exceptionally elongated and with a small contribution to the bond‐valence sum of only 6.7%. Short C—H...Br contacts build up a three‐dimensional network. The Cu...Cu distances within the chain range from 2.8390 (12) to 3.0805 (17) Å, indicating the existence of weak Cu^I...Cu^I cuprophilic interactions.     

Crystal Structures,Magnetic Properties and Catecholase‐Like Activities of μ‐Alkoxo‐μ‐Carboxylato Double Bridged Dinuclear and Tetranuclear Copper(II) Complexes

One μ‐alkoxo‐μ‐carboxylato bridged dinuclear copper(II) complex, [Cu₂(L¹)(μ‐C₆H₅CO₂)] ( 1 )(H₃L¹ = 1,3‐bis(salicylideneamino)‐2‐propanol)), and two μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear copper(II) complexes, [Cu₄(L¹)₂(μ‐C₈H₁₀O₄)(DMF)₂]·H₂O ( 2 ) and [Cu₄(L²)₂(μ‐C₅H₆O₄]·2H₂O·2CH₃CN ( 3 ) (H₃L² = 1,3‐bis(5‐bromo‐salicylideneamino)‐2‐propanol)) have been prepared and characterized. The single crystal X‐ray analysis shows that the structure of complex 1 is dimeric with two adjacent copper(II) atoms bridged by μ‐alkoxo‐μ‐carboxylato ligands where the Cu···Cu distances and Cu‐O(alkoxo)‐Cu angles are 3.5 11 Å and 132.8°, respectively. Complexes 2 and 3 consist of a μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear Cu(II) complex with mean Cu‐Cu distances and Cu‐O‐Cu angles of 3.092 Å and 104.2° for 2 and 3.486 Å and 129.9° for 3 , respectively. Magnetic measurements reveal that 1 is strong antiferromagnetically coupled with 2J =‐210 cm^?1 while 2 and 3 exhibit ferromagnetic coupling with 2J = 126 cm^?1 and 82 cm^?1 (averaged), respectively. The 2J values of 1–3 are correlated to dihedral angles and the Cu‐O‐Cu angles. Dependence of the pH at 25 °C on the reaction rate of oxidation of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) to the corresponding quinone (3,5‐DTBQ) catalyzed by 1–3 was studied. Complexes 1–3 exhibit catecholase‐like active at above pH 8 and 25 °C for oxidation of 3,5‐di‐tert‐butylcatechol.     

Di‐μ‐hydroxido‐bis{[bis(6‐methyl‐2‐pyridylmethyl)(2‐phenylethyl)amine‐κ3N′,N′′,N′′′]copper(II)} bis(perchlorate)

The title compund, [Cu₂(OH)₂(C₂₂H₂₅N₃)₂](ClO₄)₂, is a copper(II) dimer, with two [CuL]²⁺ units [L is bis(6‐methyl‐2‐pyridylmethyl)(2‐phenylethyl)amine] bridged by hydroxide groups to define the {[CuL](μ‐OH)₂[CuL]}²⁺ cation. Charge balance is provided by perchlorate counter‐anions. The cation has a crystallographic inversion centre halfway between the Cu^II ions, which are separated by 3.0161 (8) Å. The central core of the cation is an almost regular Cu₂O₂ parallelogram of sides 1.931 (2) and 1.935 (2) Å, with a Cu—O—Cu angle of 102.55 (11)°. The coordination geometry around each Cu^II centre can be best described as a square‐based pyramid, with three N atoms from L ligands and two hydroxide O atoms completing the coordination environment. Each cationic unit is hydrogen bonded to two perchlorate anions by means of hydroxide–perchlorate O—H...O interactions.     

catena‐Poly­[[[1,8‐bis(2‐hydroxy­ethyl)‐1,3,6,8,10,13‐hexa­aza­cyclo­tetra­decane]copper(II)]‐μ‐cyano‐[tri­cyano­nitro­soiron(III)]‐μ‐cyano]

The bimetallic title complex, [CuFe(CN)₅(C₁₂H₃₀N₆O₂)(NO)] or [Cu(L)Fe(CN)₅(NO)] [where L is 1,8‐bis(2‐hydroxy­ethyl)‐1,3,6,8,10,13‐hexa­aza­cyclo­tetra­decane], has a one‐dimensional zigzag polymeric –Cu(L)–NC–Fe(NO)(CN)₃–CN–Cu(L)– chain, in which the Cu^II and Fe^II centres are linked by two CN groups. In the complex, the Cu^II ion is coordinated by four N atoms from the L ligand [Cu—N(L) = 1.999 (2)–2.016 (2) Å] and two cyanide N atoms [Cu—N = 2.383 (2) and 2.902 (3) Å], and has an elongated octahedral geometry. The Fe^II centre is in a distorted octahedral environment, with Fe—N(nitroso) = 1.656 (2) Å and Fe—C(CN) = 1.938 (3)–1.948 (3) Å. The one‐dimensional zigzag chains are linked to form a three‐dimensional network via N—H⋯N and O—H⋯N hydrogen bonds.     

A novel three‐dimensional copper(II) coordination polymer with 1,4‐bis(1,2,4‐triazol‐1‐ylmeth­yl)benzene and thio­cyanate

In the title complex, poly[copper(II)‐di‐μ₂‐thio­cyanato‐μ₂‐1,4‐bis­(1,2,4‐triazol‐1‐ylmeth­yl)benzene], [Cu(NCS)₂(C₁₂H₁₂N₆)]_n, the Cu^II atom lies on an inversion centre in a tetra­gonally distorted octa­hedral environment. Four N atoms from thio­cyanate and 1,4‐bis­(1,2,4‐triazol‐1‐ylmeth­yl)benzene (bbtz) ligands fill the equatorial positions, and S atoms from symmetry‐related thio­cyanate ligands fill the axial positions. The benzene ring of the bbtz ligand lies about an inversion centre. Single thio­cyanate bridges link the Cu^II atoms into two‐dimensional sheets containing an unprecedented 16‐membered [Cu₄(μ‐NCS‐N:S)₄] ring. The bbtz ligands further link the two‐dimensional sheets into a three‐dimensional network.     

Bis{μ‐6,6′‐dimethoxy‐2,2′‐[propane‐1,2‐diylbis(iminomethylene)]diphenolato}bis[aquacopper(II)] dihydrate

In the title compound, [Cu₂(C₁₉H₂₄N₂O₄)₂(H₂O)₂]·2H₂O, the asymmetric unit consists of one half of the bis{μ‐6,6′‐dimethoxy‐2,2′‐[propane‐1,2‐diylbis(iminomethylene)]diphenolato}bis[aquacopper(II)] complex and two water molecules. Two Cu^II centres are bridged through a pair of phenolate groups, resulting in a complex with a centrosymmetric structure, with the centre of inversion at the middle of the Cu₂O₂ plane. The Cu atoms are in a slightly distorted square‐pyramidal coordination environment (τ = 0.07). The average equatorial Cu—O bond length and the axial Cu—O bond length are 1.928 (3) and 2.486 (3) Å, respectively. The Cu—O(water) bond length is 2.865 (4) Å, so the compound could be described as having a weakly coordinating water molecule at each Cu^II ion and two solvent water molecules per dimetallic unit. The Cu...Cu distance and Cu—O—Cu angle are 3.0901 (10) Å and 87.56 (10)°, respectively. The molecules are linked into a sheet by O—H...O and C—H...O hydrogen bonds parallel to the [001] plane.     

catena‐Poly[potassium [copper(II)‐μ‐isothiocyanato‐μ‐N‐salicylidene‐β‐alaninato(2–)]]

The title polymeric compound, catena‐poly­[dipotassium [bis­[μ‐N‐salicyl­idene‐β‐alaninato(2−)]‐κ⁴O,N,O′:O′′;κ⁴O′′:O,N,O′‐dicopper(II)]‐di‐μ‐iso­thio­cyanato‐κ²N:S;κ²S:N], {K[Cu(NCS)(C₁₀H₉NO₃)]}_n, consists of [iso­thio­cyanato(N‐salicyl­idene‐β‐alaninato)copper(II)]⁻ anions connected through the two three‐atom thio­cyanate (μ‐NCS) and the two anti,anti‐μ‐­carboxyl­ate bridges into infinite one‐dimensional polymeric anions, with coulombically interacting K⁺ counter‐ions with coordination number 7 constrained between the chains. The Cu^II atoms adopt a distorted tetragonal–bipyramidal coordination, with three donor atoms of the tridentate Schiff base and one N atom of the bridging μ‐NCS ligand in the basal plane. The first axial position is occupied by a thio­cyanate S atom of a symmetry‐related μ‐NCS ligand at an apical distance of 2.9770 (8) Å, and the second position is occupied by an O atom of a bridging carboxyl­ate group from an adjacent coordination unit at a distance of 2.639 (2) Å.     

μ‐Oxo‐bis{[(6‐hydroxy­methyl‐2‐pyridyl­methyl)­bis(2‐pyridyl­methyl)­amine‐κ5N,N′,N′′,N′′′,O]­iron(III)} tetrakis­(perchlorate)

The novel μ‐oxo‐diiron complex [Fe₂O(BPHPA)₂](ClO₄)₄ [BPHPA is (6‐hydroxy­methyl‐2‐pyridyl­methyl)­bis(2‐pyridyl­methyl)­amine, C₁₉H₂₀N₄O], contains a binuclear centrosymmetric [Fe₂O(BPHPA)₂]⁴⁺ cation (the bridging O atom lies on an inversion centre) and four perchlorate anions. Each iron ion is coordinated by four N atoms [Fe—N = 2.117 (5)–2.196 (5) Å] and one O atom [Fe—O = 2.052 (5) Å] from a BPHPA ligand, and by one bridging oxo atom [Fe—O = 1.7896 (9) Å], forming a distorted octahedron. There are hydrogen bonds between the hydroxy group and perchlorate O atoms [O—H·O = 2.654 (7) Å].     

catena‐Poly[[[pyridinecopper(II)]bis[μ3‐4‐(2‐oxidobenzylideneamino)benzoato]] dimethylformamide disolvate], a polymer composed of dimeric dicopper building units

The title compound, {[Cu(C₁₄H₉NO₃)(C₅H₅N)]·C₃H₇NO}_n or {[Cu₂L₂(py)₂]·2DMF}_n [py is pyridine, L is 4‐(salicylideneamino)benzoate and DMF is dimethylformamide], is composed of dimeric dicopper [CuL(py)]₂ building units, which are interlinked into a one‐dimensional chain through the formation of Cu—O_COO bonds. The dimeric unit is centrosymmetric, containing two Cu^II atoms linked by bridging phenolate O atoms into a Cu₂O₂ plane with a chelating Cu—O bond length of 1.927 (2) Å and a bridging Cu—O bond length of 2.440 (2) Å. Interchain C—H...O and π–π stacking interactions are responsible for an extensive three‐dimensional structure in which the resulting channels are filled by DMF solvent molecules.     

A twofold interwoven two‐dimensional→two‐dimensional (2‐D→2‐D) cluster–organic network based on the [Cu2I2] cluster and the 4,4′‐(diazenediyl)dipyridine ligand: poly[[μ2‐4,4′‐(diazenediyl)dipyridine]‐μ2‐iodido‐copper(I)]

In the polymeric title compound, [CuI(C₁₀H₈N₄)]_n, the Cu^I atom is in a four‐coordinated tetrahedral geometry, formed by two I atoms and two pyridine N atoms from two different 4,4′‐(diazenediyl)dipyridine (4,4′‐azpy) ligands. Two μ₂‐I atoms link two Cu^I atoms to form a planar rhomboid [Cu₂I₂] cluster located on an inversion centre, where the distance between two Cu^I atoms is 2.7781 (15) Å and the Cu—I bond lengths are 2.6290 (13) and 2.7495 (15) Å. The bridging 4,4′‐azpy ligands connect the [Cu₂I₂] clusters into a two‐dimensional (2‐D) double‐layered grid‐like network [parallel to the (10) plane], with a (4,4)‐connected topology. Two 2‐D grid‐like networks interweave each other by long 4,4′‐azpy bridging ligands to form a dense 2‐D double‐layered network. To the best of our knowledge, this interwoven 2‐D→2‐D network is observed for the first time in [Cu₂I₂]–organic compounds.     

The diselanylbis(1,3‐dimethyl‐1H‐imidazol‐3‐ium) dication stabilized by the polymeric catena‐pentachloridotricuprate(I) anion

In the title compound, catena‐poly[diselanylbis(1,3‐dimethyl‐1H‐imidazol‐3‐ium) [μ₃‐chlorido‐tetra‐μ₂‐chlorido‐tricuprate(I)]], {(C₁₀H₁₆N₄Se₂)[Cu₃Cl₅]}_n, the diselenide dication is stabilized by catena‐[Cu₃Cl₅]²⁻ anions which associate through strong Cu—Cl bonds [average length = 2.3525 (13) Å] to form polymeric chains. The polymeric [Cu₃Cl₅]²⁻ anion contains crystallographically imposed twofold rotation symmetry, with distorted trigonal‐planar and tetrahedral geometries around the two symmetry‐independent Cu atoms. Likewise, the Se—Se bond of the cation is centered on a twofold rotation axis.     

trans‐Bis(dimethyl sulfoxide‐κO)bis(3‐oxo‐3,4‐dihydroquinoxaline‐2‐carboxylato‐κ2N1,O2)copper(II)

The title compound, [Cu(C₉H₅N₂O₃)₂(C₂H₆OS)₂], consists of octahedrally coordinated Cu^II ions, with the 3‐oxo‐3,4‐dihydroquinoxaline‐2‐carboxylate ligands acting in a bidentate manner [Cu—O = 1.9116 (14) Å and Cu—N = 2.1191 (16) Å] and a dimethyl sulfoxide (DMSO) molecule coordinated axially via the O atom [Cu—O = 2.336 (5) and 2.418 (7) Å for the major and minor disorder components, respectively]. The whole DMSO molecule exhibits positional disorder [0.62 (1):0.38 (1)]. The octahedron around the Cu^II atom, which lies on an inversion centre, is elongated in the axial direction, exhibiting a Jahn–Teller effect. The ligand exhibits tautomerization by H‐atom transfer from the hydroxyl group at position 3 to the N atom at position 4 of the quinoxaline ring of the ligand. The complex molecules are linked through an intermolecular N—H...O hydrogen bond [N...O = 2.838 (2) Å] formed between the quinoxaline NH group and a carboxylate O atom, and by a weak intermolecular C—H...O hydrogen bond [3.392 (11) Å] formed between a carboxylate O atom and a methyl C atom of the DMSO ligand. There is a weak intramolecular C—H...O hydrogen bond [3.065 (3) Å] formed between a benzene CH group and a carboxylate O atom.     

A novel three‐dimensional heterometallic coordination polymer: poly[[diaquadi‐μ3‐chlorido‐μ2‐chlorido‐tri‐μ3‐nicotinato‐tricopper(I)gadolinium(III)] hemihydrate]

In the title polymeric heterometallic compound, {[Cu₃Gd(C₆H₄NO₂)₃Cl₃(H₂O)₂]·0.5H₂O}_n, comprising copper(I) and gadolinium(III) cations bridged by nicotinate (nic) ligands and chloride anions, the Gd^III centers display a bicapped trigonal prismatic geometry, defined by six carboxylate O atoms and two water molecules. For copper(I), one Cu center is three‐coordinated by three chloride ions and displays a trigonal–planar geometry; the other two Cu centers are four‐coordinated and display a very distorted tetrahedral geometry. The chloride anions act in μ₂‐ and μ₃‐bridging modes, linking the Cu^I ions into an infinite chain. The nic ligand exhibits a tridentate coordination mode, with the carboxylate O atoms linking to two Gd^III ions and the N atom linking to one Cu^I ion. Thus, a novel three‐dimensional heterometallic coordination polymer is constructed from Gd–carboxylate subunits and Cu—Cl chains. In addition, intra‐ and intermolecular O—H...O and O—H...Cl hydrogen bonds are also observed within the three‐dimensional structure. Topologically, the framework represents an unusual 3,6‐connected (4.8²)₃(4¹⁰.6⁵) net.     

Di‐μ‐methoxo‐bis({N,N′‐bis­[2‐(3,5‐di­methyl­pyrazol‐1‐yl)­ethyl]­amine‐κ3N}copper(II)) bis­(hexa­fluoro­phosphate)

The title compound, [Cu₂(C₁₄H₂₃N₅)₂(CH₃O)₂](PF₆)₂, has a doubly methoxo‐bridged centrosymmetric copper dimer cation involving two tridentate bis­(pyrazolyl)­amine ligands. The geometry of each Cu^II atom is a distorted square pyramid with two N atoms of the pyrazole in bis­[2‐(3,5‐di­methyl‐1‐pyrazolyl)­ethyl]­amine (bpea) and two μ₂‐bridging O atoms of the methoxo ligands forming the basal plane, and the amine N atom occupying the axial position. In the bridging plane, the Cu—O bond lengths are 1.940 (4) and 1.942 (4) Å, and the bond angles for O—Cu—O and Cu—O—Cu are 76.1 (2) and 103.9 (2)°, respectively. The Cu?Cu distance is 3.058 (1) Å. The central four‐membered ring lies on an inversion centre.     

2,6‐Bis(1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)pyridine and its octahedral copper complex

In the tridentate ligand 2,6‐bis(1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)pyridine, C₂₃H₁₉N₇, both sets of triazole N atoms are anti with respect to the pyridine N atom, while in the copper complex aqua[2,6‐bis(1‐benzyl‐1H‐1,2,3‐triazol‐4‐yl)pyridine](pyridine)(tetrafluoroborato)copper(II) tetrafluoroborate, [Cu(BF₄)(C₅H₅N)(C₂₃H₁₉N₇)(H₂O)]BF₄, the triazole N atoms are in the syn–syn conformation. The coordination of the Cu^II atom is distorted octahedral. The ligand structure is stabilized through intermolecular C—H...N interactions, while the crystal structure of the Cu complex is stabilized through water‐ and BF₄‐mediated hydrogen bonds. Photoluminiscence studies of the ligand and complex show that the ligand is fluorescent due to triazole–pyridine conjugation, but that the fluorescence is quenched on complexation.     

Bis[N‐(2‐hydroxy­ethyl)‐β‐alaninato]copper(II)

The Cu^II ion in the title complex, [Cu(C₅H₁₀NO₃)₂] or [Cu(He‐ala)₂] [He‐ala = N‐(2‐hydroxy­ethyl)‐β‐alaninate], resides at the inversion centre of a square bipyramid comprised of two facially arranged tridentate He‐ala ligands. Each He‐ala ligand binds to a Cu^II ion by forming one six‐membered β‐alaninate chelate ring in a twist conformation and one five‐membered ethanol­amine ring in an envelope conformation, with Cu—N = 2.017 (2) Å, Cu—O_COO = 1.968 (1) Å and Cu—O_OH = 2.473 (2) Å. The [Cu(He‐ala)₂] mol­ecules are involved in a network of O—H⋯O and N—H⋯O hydrogen bonds, forming layers parallel to the (10) plane. The layers are connected into a three‐dimensional structure by van der Waals inter­actions, so that the mol­ecular centres form pseudo‐face‐centered close packing.     

(2‐Methyl­quinolin‐8‐olato)­iron(III) and ‐copper(II) complexes

The crystal structures of tris(2‐methyl­quinolin‐8‐olato‐N,O)­iron(III), [Fe­(C₁₀­H₈­NO)₃], (I), and aqua­bis(2‐methyl­quinolin‐8‐olato‐N,O)­copper(II), [Cu­(C₁₀­H₈NO)₂­(H₂O)], (II), have been determined. Compound (I) has a distorted octahedral configuration, in which the central Fe atom is coordinated by three N atoms and three O atoms from three 2‐methylquinolin‐8‐olate ligands. The three Fe—O bond distances are in the range 1.934 (2)–1.947 (2) Å, while the three Fe—N bond distances range from 2.204 (2) to 2.405 (2) Å. In compound (II), the central Cu^II atom and H₂O group lie on the crystallographic twofold axis and the coordination geometry of the Cu^II atom is close to trigonal bipyramidal, with the three O atoms in the basal plane and the two N atoms in apical positions. The Cu—N bond length is 2.018 (5) Å. The Cu—O bond length in the basal positions is 1.991 (4) Å, while the Cu—O bond length in the apical position is 2.273 (6) Å. There is an intermolecular OW—H?O hydrogen bond which links the mol­ecules into a linear chain along the b axis.     

The heterobifunctional ligand 5‐[4‐(1,2,4‐triazol‐4‐yl)phenyl]‐1H‐tetrazole and its role in the construction of a CdII metal–organic chain structure

5‐[4‐(1,2,4‐Triazol‐4‐yl)phenyl]‐1H‐tetrazole, C₉H₇N₇, (I), an asymmetric heterobifunctional organic ligand containing triazole (tr) and tetrazole (tz) termini linked directly through a 1,4‐phenylene spacer, crystallizes in the polar space group Pc. The heterocyclic functions, serving as single hydrogen‐bond donor (tz) or acceptor (tr) units, afford hydrogen‐bonded zigzag chains with no crystallographic centre of inversion. In the structure of catena‐poly[[diaquacadmium(II)]bis{μ₂‐5‐[4‐(1,2,4‐triazol‐4‐yl)phenyl]tetrazol‐1‐ido‐κ²N¹:N^1′}], [Cd(C₉H₆N₇)₂(H₂O)₂]_n, (II), the Cd^II dication resides on a centre of inversion in an octahedral {N₄O₂} environment. In the equatorial plane, the Cd^II polyhedron is built up from four N atoms of two kinds, namely of trans‐coordinating tr and tz fragments [Cd—N = 2.2926 (17) and 2.3603 (18) Å], and the coordinating aqua ligands occupy the two apical sites. The metal centres are separated at a distance of 11.1006 (7) Å by means of the double‐bridging tetrazolate anion, L⁻, forming a chain structure. The water ligands and tz fragments interact with one another, like a double hydrogen‐bond donor–acceptor synthon, leading to a hydrogen‐bonded three‐dimensional array.     

Silver(I) sulfate coordination polymers with 4,4′‐bipyridazine and pyridazino[4,5‐d]pyridazine

Poly[[μ₄‐4,4′‐bipyridazine‐μ₅‐sulfato‐disilver(I)] monohydrate], {[Ag₂(SO₄)(C₈H₆N₄)]·H₂O}_n, (I), and poly[[aqua‐μ₄‐pyridazino[4,5‐d]pyridazine‐μ₃‐sulfato‐disilver(I)] monohydrate], {[Ag₂(SO₄)(C₆H₄N₄)(H₂O)]·H₂O}_n, (II), possess three‐ and two‐dimensional polymeric structures, respectively, supported by N‐tetradentate coordination of the organic ligands [Ag—N = 2.208 (3)–2.384 (3) Å] and O‐pentadentate coordination of the sulfate anions [Ag—O = 2.284 (3)–2.700 (2) Å]. Compound (I) is the first structurally examined complex of the new ligand 4,4′‐bipyridazine; it is based upon unprecedented centrosymmetric silver–pyridazine tetramers with tetrahedral AgN₂O₂ and trigonal–bipyramidal AgN₂O₃ coordination of two independent Ag^I ions. Compound (II) adopts a typical dimeric silver–pyridazine motif incorporating two kinds of square‐pyramidal AgN₂O₃ Ag^I ions. The structure exhibits short anion–π interactions involving noncoordinated sulfate O atoms [O...π = 3.041 (3) Å].