1,4‐Di­methyl­pyridinium hexakis­(di­methyl­form­amide‐κO)­calcium(II) dodecamolybdophosphate

In the title compound, (C₇H₁₀N)[Ca(C₃H₇NO)₆][PMo₁₂O₄₀], two types of cations {viz. 1,4‐di­methyl­pyridinium and a [Ca(DMF)₆]²⁺ complex cation (DMF is di­methyl­form­amide)} and dodecamolybdophosphate (tetra­conta­oxo­phos­phido­dodeca­molybdate) anions form an infinite three‐dimensional assembly via electrostatic forces.     

A three‐dimensional manganese(II) metal–organic framework based on 5‐methoxybenzene‐1,3‐dicarboxylic acid and exhibiting a pts net

The solvothermal reaction of MnCl₂·H₂O and 5‐methoxybenzene‐1,3‐dicarboxylic acid (MeO‐m‐H₂BDC) led to a three‐dimensional Mn^II metal–organic framework, namely poly[(dimethylformamide‐κO)(μ₄‐5‐methoxybenzene‐1,3‐dicarboxylato‐κ⁴O¹:O^1′:O³,O^3′:O³)manganese(II)], [Mn(C₉H₆O₅)(C₃H₇NO)]_n or [Mn(MeO‐m‐BDC)(DMF)]_n (DMF is dimethylformamide). The Mn^II atom is six‐coordinated and exhibits a distorted octahedral geometry formed by five carboxylate O atoms from four different MeO‐m‐BDC²⁻ anionic ligands and by one DMF O atom. The three‐dimensional framework of (I) formed by the bridging MeO‐m‐BDC²⁻ ligands and the Mn^II atoms exhibits a pts topological network when MeO‐m‐BDC²⁻ and Mn^II are viewed as four‐connected nodes.     

1:1 Adducts of 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid with dimethylammonium and 4,4′‐bipyridine

The title compounds, dimethylammonium 2‐{4‐[1‐(4‐carboxymethoxyphenyl)‐1‐methylethyl]phenoxy}acetate, C₂H₈N⁺·C₁₉H₁₉O₆⁻, (I), and 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid–4,4′‐bipyridine (1/1), C₁₉H₂₀O₆·C₁₀H₈N₂, (II), are 1:1 adducts of 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid (H₂L) with dimethylammonium or 4,4′‐bipyridine. The component ions in (I) are linked by N—H...O, O—H...O and C—H...O hydrogen bonds into continuous two‐dimensional layers parallel to the (001) plane. Adjacent layers are stacked via C—H...O hydrogen bonds into a three‐dimensional network with an –ABAB– alternation of the two‐dimensional layers. In (II), two H₂L molecules, one bipy molecule and two half bipy molecules are linked by O—H...N hydrogen bonds into one‐dimensional chains and rectanglar‐shaped rings. They are assembled viaπ–π stacking interactions and C—H...O hydrogen bonds into an intriguing zero‐dimensional plus one‐dimensional poly(pseudo)rotaxane motif.     

Probing the supramolecular interaction synthons of 1‐benzofuran‐2,3‐dicarboxylic acid in its monoanionic form

1‐Benzofuran‐2,3‐dicarboxylic acid (C₁₀H₆O₅) is a dicarboxylic acid ligand which can readily engage in organometallic complexes with various metal ions. This ligand is characterized by an intramolecular hydrogen bond between the two carboxyl residues, and, as a monoanionic species, readily forms supramolecular adducts with different organic and inorganic cations. These are a 1:1 adduct with the dimethylammonium cation, namely dimethylammonium 3‐carboxy‐1‐benzofuran‐2‐carboxylate, C₂H₈N⁺·C₁₀H₅O₅⁻, (I), a 2:1 complex with Cu²⁺ ions in which four neutral imidazole molecules also coordinate the metal atom, namely bis(3‐carboxy‐1‐benzofuran‐2‐carboxylato‐κO³)tetrakis(1H‐imidazole‐κN³)copper(II), [Cu(C₁₀H₅O₅)₂(C₃H₄N₂)₄], (II), and a 4:1 adduct with [La(H₂O)₇]³⁺ ions, namely heptaaquabis(3‐carboxy‐1‐benzofuran‐2‐carboxylato‐κO³)lanthanum 3‐carboxy‐1‐benzofuran‐2‐carboxylate 1‐benzofuran‐2,3‐dicarboxylic acid solvate tetrahydrate, [La(C₁₀H₅O₅)₂(H₂O)₇](C₁₀H₅O₅)·C₁₀H₆O₅·4H₂O, (III). In the crystal structure, complex (II) resides on inversion centres, while complex (III) resides on axes of twofold rotation. The crystal packing in all three structures reveals π–π stacking interactions between the planar aromatic benzofuran residues, as well as hydrogen bonding between the components. The significance of this study lies in the first crystallographic characterization of the title framework, which consistently exhibits the presence of an intramolecular hydrogen bond and a consequent monoanionic‐only nature. It shows further that the anion can coordinate readily to metal cations as a ligand, as well as acting as a monovalent counter‐ion. Finally, the aromaticity of the flat benzofuran residue provides an additional supramolecular synthon that directs and facilitates the crystal packing of compounds (I)–(III).     

Cationic,neutral and anionic metal(II) complexes derived from 4‐oxo‐4H‐pyran‐2,6‐dicarboxylic acid (chelidonic acid)

The structures of five metal complexes containing the 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate dianion illustrate the remarkable coordinating versatility of this ligand and the great structural diversity of its complexes. In tetraaquaberyllium 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate, [Be(H₂O)₄](C₇H₂O₆), (I), the ions are linked by eight independent O—H...O hydrogen bonds to form a three‐dimensional hydrogen‐bonded framework structure. Each of the ions in hydrazinium(2+) diaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)calcate, (N₂H₆)[Ca(C₇H₂O₆)₂(H₂O)₂], (II), lies on a twofold rotation axis in the space group P2/c; the anions form hydrogen‐bonded sheets which are linked into a three‐dimensional framework by the cations. In bis(μ‐4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)bis[tetraaquamanganese(II)] tetrahydrate, [Mn₂(C₇H₂O₆)₂(H₂O)₈]·4H₂O, (III), the metal ions and the organic ligands form a cyclic centrosymmetric Mn₂(C₇H₂O₆)₂ unit, and these units are linked into a complex three‐dimensional framework structure containing 12 independent O—H...O hydrogen bonds. There are two independent Cu^II ions in tetraaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)copper(II), [Cu(C₇H₂O₆)(H₂O)₄], (IV), and both lie on centres of inversion in the space group P; the metal ions and the organic ligands form a one‐dimensional coordination polymer, and the polymer chains are linked into a three‐dimensional framework containing eight independent O—H...O hydrogen bonds. Diaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)cadmium monohydrate, [Cd(C₇H₂O₆)(H₂O)₂]·H₂O, (V), forms a three‐dimensional coordination polymer in which the organic ligand is coordinated to four different Cd sites, and this polymer is interwoven with a complex three‐dimensional framework built from O—H...O hydrogen bonds.     

[H3N(CH2)5NH3]·AlP2O8H,a one‐dimensional aluminophosphate

The structure of the title compound, pentane‐1,5‐di­ammonium aluminium(III) hydrogen bis(phosphate), (C₅H₁₆N₂)[AlP₂O₈H], obtained solvothermally at 473 K, has been determined by single‐crystal X‐ray diffraction. It consists of one‐dimensional [AlP₂O₈H]^2? macroanions, connected to each other by pentane­di­ammonium cations. Contrary to similar compounds with P/Al = 2, the three‐dimensional structure is mainly obtained via a network of hydrogen bonds.     

Controlled Reactivity Tuning of Metal‐Functionalized Vanadium Oxide Clusters

Controlling the assembly and functionalization of molecular metal oxides [M_xO_y]^n? (M=Mo, W, V) allows the targeted design of functional molecular materials. While general methods exist that enable the predetermined functionalization of tungstates and molybdates, no such routes are available for molecular vanadium oxides. Controlled design of polyoxovanadates, however, would provide highly active materials for energy conversion, (photo‐) catalysis, molecular magnetism, and materials science. To this end, a new approach has been developed that allows the reactivity tuning of vanadium oxide clusters by selective metal functionalization. Organic, hydrogen‐bonding cations, for example, dimethylammonium are used as molecular placeholders to block metal binding sites within vanadate cluster shells. Stepwise replacement of the placeholder cations with reactive metal cations gives mono‐ and difunctionalized clusters. Initial reactivity studies illustrate the tunability of the magnetic, redox, and catalytic activity.     

Three‐Dimensional MOF‐Type Architectures with Tetravalent Uranium Hexanuclear Motifs (U6O8)

Four metal–organic frameworks (MOF) with tetravalent uranium have been solvothermally synthesized by treating UCl₄ with rigid dicarboxylate linkers in N,N‐dimethylfomamide (DMF). The use of the ditopic ligands 4,4′‐biphenyldicarboxylate ( 1 ), 2,6‐naphthalenedicarboxylate ( 2 ), terephthalate ( 3 ), and fumarate ( 4 ) resulted in the formation of three‐dimensional networks based on the hexanuclear uranium‐centered motif [U₆O₄(OH)₄(H₂O)₆]. This motif corresponds to an octahedral configuration of uranium nodes and is also known for thorium in crystalline solids. The atomic arrangement of this specific building unit with organic linkers is similar to that found in the zirconium‐based porous compounds of the UiO‐66/67 series. The structure of [U₆O₄(OH)₄(H₂O)₆(L)₆] ? X (L=dicarboxylate ligand; X=DMF) shows the inorganic hexamers connected in a face‐centered cubic manner through the ditopic linkers to build up a three‐dimensional framework that delimits octahedral (from 5.4 Å for 4 up to 14.0 Å for 1 ) and tetrahedral cavities. The four compounds have been characterized by using single‐crystal X‐ray diffraction analysis (or powder diffraction analysis for 4 ). The tetravalent state of uranium has been examined by using XPS and solid‐state UV/Vis analyses. The measurement of the Brunauer–Emmett–Teller surface area indicated very low values (Langmuir <300 m² g^?1 for 1 , <7 m² g^?1 for 2 – 4 ) and showed that the structures are quite unstable upon removal of the encapsulated DMF solvent.     

Poly[μ7‐sulfanediyldiacetato‐disilver(I)]

In the title coordination polymer, [Ag₂(C₄H₄O₄S)], each Ag^I cation is four‐coordinated by three of the four carboxylate O atoms and the S atom from symmetry‐related sulfanediyldiacetate ligands, thus defining a distorted tetrahedral geometry at the metal centre. The Ag^I cations are bridged by sulfanediyldiacetate groups, leading to a two‐dimensional layer structure. These layers are interconnected via Ag—S bonds to form a three‐dimensional coordination polymer network overall.     

Poly[[tetrachlorido{μ4‐tetrakis[(pyridin‐4‐yl)oxymethyl]methane‐κ4N:N′:N′′:N′′′}dizinc(II)] dimethylformamide tetrasolvate]

A novel metal–organic framework, {[Zn₂Cl₄(C₂₅H₂₄N₄O₄)]·4C₃H₇NO}_n, has been synthesized solvothermally by assembling the semi‐rigid tetrahedral ligand tetrakis[(pyridin‐4‐yl)oxymethyl]methane (tpom) and zinc nitrate in dimethylformamide (DMF). The crystal structure is noncentrosymmetric (P2₁c). Each Zn^II cation has a tetrahedral coordination environment (C₂ symmetry), which is formed by two chloride ligands and two pyridine N atoms from two tpom ligands. The tetrahedral tetradentate tpom linker has a quaternary C atom located on the crystallographic axis. This linker utilizes all the peripheral pyridine N atoms to connect four Zn^II cations, thereby forming a wave‐like two‐dimensional sheet along the c axis. The two‐dimensional layer can be topologically simplified as a typical uninodal 4‐connected sql/Shubnikov net, which is represented by the Schläfli symbol {4⁴,6²}. Adjacent layers are further packed into a three‐dimensional structure by C—H...Cl hydrogen bonds.     

A three‐dimensional ZnII coordination polymer constructed from 1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands exhibiting photoluminescence

Ligands based on polycarboxylic acids are excellent building blocks for the construction of coordination polymers; they may bind to a variety of metal ions and form clusters, as well as extended chain or network structures. Among these building blocks, biphenyltetracarboxylic acids (H₄bpta) with C ₂ symmetry have recently attracted attention because of their variable bridging and multidentate chelating modes. The new luminescent three‐dimensional coordination polymer poly[(μ₅‐1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylato)bis[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene]dizinc(II)], [Zn₂(C₁₆H₆O₈)(C₁₂H₁₀N₄)]_n , was synthesized solvothermally and characterized by single‐crystal X‐ray diffraction, elemental analysis and IR spectroscopy. The crystal structure contains two crystallographically independent Zn^II cations. Both metal cations are located on twofold axes and display distorted tetrahedral coordination geometries. Neighbouring Zn^II centres are bridged by carboxylate groups in the syn –anti mode to form one‐dimensional chains. Adjacent chains are linked through 1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands to form a three‐dimensional network. In the solid state, the compound exhibits blue photoluminescence and represents a promising candidate for a thermally stable and solvent‐resistant blue fluorescent material.     

A new ZnII coordination polymer based on 4‐(pyridin‐4‐yl)benzoic and formic acids: in‐situ synthesis,crystal structure and luminescence properties

The title compound, poly[(μ₂‐formato‐κ³O,O′:O)[μ₂‐4‐(pyridin‐4‐yl)benzoato‐κ³N:O,O′]zinc(II)], [Zn(C₁₂H₈NO₂)(HCOO)]_n, has been synthesized in situ and characterized by thermogravimetric analysis (TGA) and single‐crystal and powder X‐ray diffraction analyses. The polymer contains two independent structural units in the asymmetric unit. These are constructed from Zn²⁺ ions, 4‐(pyridin‐4‐yl)benzoate (4‐pbc) bridges and in‐situ‐generated formate ligands, forming two similar two‐dimensional (2D) layer structures. These similar 2D layers are arranged alternately and are linked with each other by dense C—H…O hydrogen bonds to generate a three‐dimensional (3D) supramolecular framework. The crystal is pseudomerohedrally twinned about [201]. Compared with free 4‐Hpbc, the polymer exhibits a red shift and significantly enhanced solid‐state luminescence properties.     

[μ3‐cis‐N‐(2‐Aminoethyl)‐N′‐(2‐carboxylatophenyl)oxamidato(3−)]bis(2,2′‐diamino‐4,4′‐bi‐1,3‐thiazole)tetracopper(II) bis(2,4,6‐trinitrophenolate)

The title complex, [Cu₄(C₁₁H₁₀N₃O₄)₂(C₆H₆N₄S₂)₂](C₆H₂N₃O₇)₂, consists of a circular tetracopper(II) cation with an embedded inversion centre and two uncoordinated picrate (2,4,6‐trinitrophenolate) anions. The Cu^II cations at the inner sites of N‐(2‐aminoethyl)‐N′‐(2‐carboxylatophenyl)oxamidate(3−) (oxbe) have square‐planar environments and those at the outer sites are in square‐pyramidal geometries. The separations of pairs of Cu^II cations bridged by cis‐oxamide and carboxylate groups are 5.2217 (5) and 5.2871 (5) Å, respectively. The tetracopper(II) cations and picrate anions are connected by N—H...O hydrogen bonds into a two‐dimensional network parallel to the (010) plane, and these two‐dimensional networks are assembled by two types of π–π stacking interactions into a three‐dimensional supramolecular structure.     

Metal‐directed supramolecular architectures based on the bifunctional ligand 2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalic acid

By the solvothermal reactions of 2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalic acid (H₂L) with transition‐metal ions, two novel polymeric complexes, namely, poly[diaqua[μ₄‐2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalato]cobalt(II)], [Co(C₁₂H₆N₆O₄)(H₂O)₂]_n, ( 1 ), and poly[[diaqua[μ₄‐2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalato]nickel(II)] dihydrate], {[Ni(C₁₂H₆N₆O₄)(H₂O)₂]·2H₂O}_n, ( 2 ), were isolated. Both polymers have been characterized by FT–IR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction analysis. The complexes have similar two‐dimensional layered structures and coordination modes. Furthermore, the two‐dimensional layered structures bear distinct intermolecular hydrogen‐bonding interactions and π–π stacking interactions to form two different three‐dimensional supramolecular networks based on 4⁴‐subnets. The structural variation depends on the nature of the metal cations. The results of variable‐temperature magnetization measurements (χ_MT?T and χ_M^?1?T) show that complexes ( 1 ) and ( 2 ) display antiferromagnetic behaviour.     

A novel LaIII‐based metal–organic framework (MOF) with a new topology: poly[diaquabis(μ5‐2,5‐dioxopiperazine‐1,4‐diacetato)(μ2‐oxalato)dilanthanum(III)]

In the title metal–organic framework (MOF), [La(C₈H₈N₂O₆)(C₂O₄)_0.5(H₂O)]_n, the La^III cation is coordinated by eight O atoms in a square antiprismatic configuration. Each La^III cation is connected to adjacent La^III cations by bridging 2,5‐dioxopiperazine‐1,4‐diacetate (PODC²⁻) and oxalate (lying about an inversion centre) ligands, generating two‐dimensional grid layers. The layers are further linked via the carboxylate groups of the PODC²⁻ ligands in syn–syn and syn–anti modes, resulting in a three‐dimensional framework with a short Schläfli vertex notation of {4⁷.6³}{4⁷.6⁷.8}.     

New organic–inorganic frameworks incorporating iso‐ and heteropolymolybdate units and a 3,3′,5,5′‐tetramethyl‐4,4′‐bi‐1H‐pyrazole‐2,2′‐diium multiple hydrogen‐bond donor

Poly[bis(3,3′,5,5′‐tetramethyl‐4,4′‐bi‐1H‐pyrazole‐2,2′‐diium) γ‐octamolybdate(VI) dihydrate], {(C₁₀H₁₆N₄)₂[Mo₈O₂₆]·2H₂O}_n, (I), and bis(3,3′,5,5′‐tetramethyl‐4,4′‐bi‐1H‐pyrazole‐2,2′‐diium) α‐dodecamolybdo(VI)silicate tetrahydrate, (C₁₀H₁₆N₄)₂[SiMo₁₂O₄₀]·4H₂O, (II), display intense hydrogen bonding between the cationic pyrazolium species and the metal oxide anions. In (I), the asymmetric unit contains half a centrosymmetric γ‐type [Mo₈O₂₆]⁴⁻ anion, which produces a one‐dimensional polymeric chain by corner‐sharing, one cation and one water molecule. Three‐centre bonding with 3,3′,5,5′‐tetramethyl‐4,4′‐bi‐1H‐pyrazole‐2,2′‐diium, denoted [H₂Me₄bpz]²⁺ [N...O = 2.770 (4)–3.146 (4) Å], generates two‐dimensional layers that are further linked by hydrogen bonds involving water molecules [O...O = 2.902 (4) and 3.010 (4) Å]. In (II), each of the four independent [H₂Me₄bpz]²⁺ cations lies across a twofold axis. They link layers of [SiMo₁₂O₄₀]⁴⁻ anions into a three‐dimensional framework, and the preferred sites for pyrazolium/anion hydrogen bonding are the terminal oxide atoms [N...O = 2.866 (6)–2.999 (6) Å], while anion/aqua interactions occur preferentially viaμ₂‐O sites [O...O = 2.910 (6)–3.151 (6) Å].     

The coordination polymer poly[(μ3‐3‐aminocarbonylpyrazine‐2‐carboxylato‐κ3N1:O2:O2′)silver(I)]

The title compound, [Ag(C₆H₄N₃O₃)]_n or [Ag(pyzca)]_n (where pyzca is 3‐aminocarbonylpyrazine‐2‐carboxylate), (I), was obtained by silver‐catalysed partial hydrolysis of pyrazine‐2,3‐dicarbonitrile in aqueous solution. The compound has a distorted trigonal–planar coordination geometry around the Ag^I ion, with each ligand bridging three Ag^I ions to form a one‐dimensional strand of molecules parallel to the b axis. An extensive hydrogen‐bond pattern connects these strands to form a three‐dimensional network of mog topology.     

A novel three‐dimensional SrII coordination polymer based on benzene‐1,2,4,5‐tetracarboxylate: hydrothermal synthesis,crystal structure and spectroscopic and thermal studies

Coordination of the anions of benzenecarboxylic acids with metal cations leads to coordination polymers with various structural features. Very few examples of strontium‐based structures have been reported. A new three‐dimensional coordination polymer, namely poly[aqua(μ₁₂‐benzene‐1,2,4,5‐tetracarboxylato)distrontium(II)], [Sr₂(C₁₀H₂O₈)(H₂O)]_n , has been synthesized under hydrothermal conditions and characterized by thermal analysis, vibrational spectroscopy (Raman and IR), single‐crystal X‐ray diffraction and powder X‐ray diffraction. The coordination geometries around the two independent Sr^II ions can be described as a distorted dodecahedron and a distorted monocapped square antiprism. The compound features a three‐dimensional structure containing inorganic motifs, with two‐dimensional layers connected through organic linkers, and possesses a topologic structure of a binodal (6,12) connected alb net with the Schläfli symbol {4¹⁵}₂{4⁴⁸.6¹⁸}. The final product of thermal decomposition is strontium oxide (SrO).     

A new three‐dimensional cobalt(II) coordination polymer with a 4‐connected CdSO4‐like topology

The title cobalt(II) coordination polymer, poly[[diaquacobalt(II)]‐μ₄‐3,3′‐(p‐phenylene)diacrylato], [Co(C₁₂H₈O₄)(H₂O)₂]_n, was obtained by reaction of Co(NO₃)₂·6H₂O and 3,3′‐(p‐phenylene)diacrylic acid (H₂L) under hydrothermal conditions. Each Co^II cation sits on a centre of inversion and is hexacoordinated by six O‐atom donors in an octahedral geometry. The Co^II centres are connected by four centrosymmetric L²⁻ anions, resulting in a three‐dimensional framework structure. The coordinated water molecules and carboxylate O atoms form hydrogen‐bond interactions, stabilizing the structure of the three‐dimensional framework. Topologically, the framework represents a rare example of the three‐dimensional 4‐connected CdSO₄ network type. The metal cations and the organic ligand both show in‐plane coordination with respect to the extended structure.     

Two different one‐dimensional CdII halide coordination polymers constructed through bridging carboxylate ligands

Two cadmium halide complexes, catena‐poly[[chloridocadmium(II)]‐di‐μ‐chlorido‐[chloridocadmium(II)]‐bis[μ₂‐4‐(dimethylamino)pyridin‐1‐ium‐1‐acetate]‐κ³O:O,O′;κ³O,O′:O], [CdCl₂(C₉H₁₂N₂O₂)]_n, (I), and catena‐poly[1‐cyanomethyl‐1,4‐diazoniabicyclo[2.2.2]octane [[dichloridocadmium(II)]‐μ‐oxalato‐κ⁴O¹,O²:O^1′,O^2′] monohydrate], {(C₈H₁₅N₃)[CdCl₂(C₂O₄)]·H₂O}_n, (II), were synthesized in aqueous solution. In (I), the Cd^II cation is octahedrally coordinated by three O atoms from two carboxylate groups and by one terminal and two bridging chloride ligands. Neighbouring Cd^II cations are linked together by chloride anions and bridging O atoms to form a one‐dimensional zigzag chain. Hydrogen‐bond interactions are involved in the formation of the two‐dimensional network. In (II), each Cd^II cation is octahedrally coordinated by four O atoms from two oxalic acid ligands and two terminal Cl⁻ ligands. Neighbouring Cd^II cations are linked together by oxalate groups to form a one‐dimensional anionic chain, and the water molecules and organic cations are connected to this one‐dimensional zigzag chain through hydrogen‐bond interactions.