Study of the reaction Fe(CN)5(4‐CNpy)3− + S2O82− in aqueous salt and micellar solutions

The reaction Fe(CN)₅(4‐CNpy)³⁻ + S₂O₈²⁻ (4‐CNpy=4‐cyanopyridine) was studied in aqueous salt solutions in the presence of several electrolytes as well as in anionic, cationic, and nonionic surfactant solutions. In aqueous salt solutions the noncoulombic interactions seem to be important in determining the positive salt effects observed. The salting effects are influencing the activity coefficients of any participant in the reaction, including those ion pairs which can be formed between the anionic reagents and the cations which come from the added salts. The changes in surfactant concentration in anionic and nonionic surfactant solutions do not affect the reaction rate, which is similar to that in pure water at the same ionic strength. In cationic micellar solutions an increase in the rate constant compared to that in pure water is found; the reaction rate decreasing when the surfactant concentration increases. The kinetic trends can be explained assuming that the reagents are totally bound to the micelles and, therefore, an increase in the surfactant concentration results in a decrease in the reagent concentrations at the micellar phase and thus in a decrease in the observed rate constant. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet: 31: 229–235, 1999     

Study of the bromide oxidation by bromate in zwitterionic micellar solutions

The redox reaction Br⁻ + BrO₃⁻ has been studied in aqueous zwitterionic micellar solutions of N‐tetradecyl‐N, N‐dimethyl‐3‐ammonio‐1‐propanesulfonate, SB3‐14, and N‐hexadecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propanesulfonate, SB3‐16. A simple expression for the observed rate constant, k_obs, based on the pseudophase model, could explain the influences of changes in the surfactant concentration on k_obs. The kinetic effect of added NaClO₄ on the reaction rate in SB3‐14 micellar solutions has also been studied. They were rationalized by considering the binding of the perchlorate anions to the sulfobetaine micelles and their competition with the reactive bromide ions for the micellar surface. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 388–394, 2000     

Atom Exchange Versus Reconstruction: (GexAs4−x)x− (x=2, 3) as Building Blocks for the Supertetrahedral Zintl Cluster [Au6(Ge3As)(Ge2As2)3]3−

The Zintl anion (Ge₂As₂)^2? represents an isostructural and isoelectronic binary counterpart of yellow arsenic, yet without being studied with the same intensity so far. Upon introducing [(PPh₃)AuMe] into the 1,2‐diaminoethane (en) solution of (Ge₂As₂)^2?, the heterometallic cluster anion [Au₆(Ge₃As)(Ge₂As₂)₃]^3? is obtained as its salt [K(crypt‐222)]₃[Au₆(Ge₃As)(Ge₂As₂)₃]?en?2 tol ( 1 ). The anion represents a rare example of a superpolyhedral Zintl cluster, and it comprises the largest number of Au atoms relative to main group (semi)metal atoms in such clusters. The overall supertetrahedral structure is based on a (non‐bonding) octahedron of six Au atoms that is face‐capped by four (Ge_xAs_4?x)^x? (x=2, 3) units. The Au atoms bind to four main group atoms in a rectangular manner, and this way hold the four units together to form this unprecedented architecture. The presence of one (Ge₃As)^3? unit besides three (Ge₂As₂)^2? units as a consequence of an exchange reaction in solution was verified by detailed quantum chemical (DFT) calculations, which ruled out all other compositions besides [Au₆(Ge₃As)(Ge₂As₂)₃]^3?. Reactions of the heavier homologues (Tt₂Pn₂)^2? (Tt=Sn, Pb; Pn=Sb, Bi) did not yield clusters corresponding to that in 1 , but dimers of ternary nine‐vertex clusters, {[AuTt₅Pn₃]₂}^4? (in 2 – 4 ; Tt/Pn=Sn/Sb, Sn/Bi, Pb/Sb), since the underlying pseudo‐tetrahedral units comprising heavier atoms do not tend to undergo the said exchange reactions as readily as (Ge₂As₂)^2?, according to the DFT calculations.     

A ruthenium(II) complex with p‐cymene and (S)‐2‐(anilinomethyl)pyrrolidine

The title compound, [(S)‐2‐(anilino­methyl)­pyrrolidine‐N,N′]‐chloro(η⁶‐para‐cymene)­ruthenium(II) chloride, [RuCl‐(C₁₀H₁₄)(C₁₁H₁₆N₂)]Cl, has been synthesized by the reaction of [RuCl₂(p‐cymene)]₂ (p‐cymene is para‐iso­propyl­toluene) with (S)‐2‐(anilinomethyl)­pyrrolidine in triethyl­amine/2‐propanol. The Ru atom is in a pseudo‐tetrahedral environment coordinated by a chloride ligand, the aromatic hydro­carbon is linked in a η⁶ manner and the amine is linked via its two N atoms. The chloride anion is involved in hydrogen bonding with the di­amine moieties through N—H?Cl interactions, with N?Cl distances of 3.273 (4) and 3.352 (4) Å.     

Detection of Cyclo‐N5− in THF Solution

Compelling evidence has been found for the formation and direct detection of the cyclopentazole anion (cyclo‐N₅^?) in solution. The anion was prepared from phenylpentazole in two steps: reduction by an alkali metal to form the phenylpentazole radical anion, followed by thermal dissociation to yield cyclo‐N₅^?. The reaction solution was analyzed by HPLC coupled with negative mode mass spectrometry. A signal with m/z 70 was eluted about 2.1 min after injection of the sample. Its identification as N₅ was supported by single and double labeling with ¹⁵N, which yielded signals at m/z=71 and 72, respectively, with identical retention times in the HPLC column. MS/MS analysis of the m/z=70 signal revealed a dissociation product with m/z=42, which can be assigned to N₃^?. To our knowledge this is the first preparation of cyclo‐N₅^? in the bulk. The compound is indefinitely stable at temperatures below ?40 °C, and has a half‐life of a few minutes at room temperature.     

Aqueous Sulfate Separation by Sequestration of [(SO4)2(H2O)4]4− Clusters within Highly Insoluble Imine‐Linked Bis‐Guanidinium Crystals

Selective crystallization of sulfate with a simple bis‐guanidinium ligand, self‐assembled in situ from terephthalaldehyde and aminoguanidinium chloride, was employed as an effective way to separate the highly hydrophilic sulfate anion from aqueous solutions. The resulting bis‐iminoguanidinium sulfate salt has exceptionally low aqueous solubility (K_sp=2.4×10^?10), comparable to that of BaSO₄. Single‐crystal X‐ray diffraction analysis showed the sulfate anions are sequestered as [(SO₄)₂(H₂O)₄]^4? clusters within the crystals. Variable‐temperature solubility measurements indicated the sulfate crystallization is slightly endothermic (ΔH_cryst=3.7 kJ mol^?1), thus entropy driven. The real‐world utility of this crystallization‐based approach for sulfate separation was demonstrated by removing up to 99 % of sulfate from seawater in a single step.     

1‐Oxa‐nido‐dodecaborate [OB11H12]− from the Controlled Oxidation of the closo‐Borates [B11H11]2− and [B12H12]2−

The closo‐dodecaborate [B₁₂H₁₂]^2? is degraded at room temperature by oxygen in an acidic aqueous solution in the course of several weeks to give B(OH)₃. The degradation is induced by Ag²⁺ ions, generated from Ag⁺ by the action of H₂S₂O₈. Oxa‐nido‐dodecaborate(1?) is an intermediate anion, that can be separated from the reaction mixture as [NBzlEt₃][OB₁₁H₁₂] after five days in a yield of 18 %. The action of FeCl₃ on the closo‐undecaborate [B₁₁H₁₁]^2? in an aqueous solution gives either [B₂₂H₂₂]^2? (by fusion) or nido‐B₁₁H₁₃(OH)^? (by protonation and hydration), depending on the concentration of FeCl₃. In acetonitrile, however, [B₁₁H₁₁]^2? is transformed into [OB₁₁H₁₂]^? by Fe³⁺ and oxygen. The radical anions [B₁₂H₁₂] ^{˙ ?} and [B₁₁H₁₁] ^{˙ ?} are assumed to be the primary products of the oxidation with the one‐electron oxidants Ag²⁺ and Fe³⁺, respectively. These radical anions are subsequently transformed into [OB₁₁H₁₂]^? by oxygen. The crystal structure analysis shows that the structure of [OB₁₁H₁₂]^? is derived from the hypothetical closo‐oxaborane OB₁₂H₁₂ by removal of the B3 vertex, leaving a non‐planar pentagonal aperture with a three‐coordinate O vertex, as predicted by NMR spectra and theory.     

Poly[[sesqui[μ2‐1,4‐bis(imidazol‐1‐ylmethyl)benzene‐κ2N:N′](carbonato‐κ2O,O′)copper(II)] 1,4‐bis(imidazol‐1‐ylmethyl)benzene hemisolvate pentahydrate]

The asymmetric unit of the title compound, {[Cu(CO₃)(C₁₄H₁₄N₄)_1.5]·0.5C₁₄H₁₄N₄·5H₂O}_n, contains one Cu^II cation in a slightly distorted square‐pyramidal coordination environment, one CO₃²⁻ anion, one full and two half 1,4‐bis(imidazol‐1‐ylmethyl)benzene (bix) ligands, one half‐molecule of which is uncoordinated, and five uncoordinated water molecules. One of the coordinated bix ligands and the uncoordinated bix molecule are situated about centers of symmetry, located at the centers of the benzene rings. The coordinated bix ligands link the copper(II) ions into a [Cu(bix)_1.5]_n molecular ladder. These molecular ladders do not form interpenetrated ladders but are arranged in an ABAB parallel terrace, i.e. with the ladders arranged one above another, with sequence A translated with respect to B by 8 Å. To best of our knowledge, this arrangement has not been observed in any of the molecular ladder frameworks synthesized to date. The coordination environment of the Cu^II atom is completed by two O atoms of the CO₃²⁻ anion. The framework is further strengthened by extensive O—H...O and O—H...N hydrogen bonds involving the water molecules, the O atoms of the CO₃²⁻ anion and the N atoms of the bix ligands. This study describes the first example of a molecular ladder coordination polymer based on bix and therefore demonstrates further the usefulness of bix as a versatile multidentate ligand for constructing coordination polymers with interesting architectures.     

Two transition metal coordination polymers of the 7,7,8,8‐tetracyanoquinodimethane dianion (TCNQ2−)

Each of the two novel title transition metal coordination polymers, namely catena‐poly[[bis{[tris(2‐pyridylmethyl)amine]cobalt(II)}‐μ₄‐7,7,8,8‐tetracyanoquinodimethanide(2−)] bis[7,7,8,8‐tetracyanoquinodimethanide(1−)] methanol disolvate], {[Co₂(C₁₂H₄N₄)(C₁₈H₁₈N₄)₂](C₁₂H₄N₄)₂·2CH₃OH}_n, (I), and catena‐poly[[[[tris(2‐pyridylmethyl)amine]iron(II)]‐μ₂‐7,7,8,8‐tetracyanoquinodimethanide(2−)] methanol solvate], {[Fe(C₁₂H₄N₄)(C₁₈H₁₈N₄)]·CH₃OH}_n, (II), contains η⁴‐TPA and cis‐bridging TCNQ²⁻ ligands [TPA is tris(2‐pyridylmethyl)amine and TCNQ is 7,7,8,8‐tetracyanoquinodimethane], but the two compounds adopt entirely different structural motifs. Compound (I) consists of a ribbon coordination polymer featuring μ₄‐TCNQ²⁻ radical anion ligands bridging four different octahedral Co^II centers. Each formula unit of the polymer is flanked by two uncoordinated TCNQ⁻ anions and two methanol solvent molecules. All three TCNQ anions have crystallographic inversion symmetry. In (II), the 2₁ symmetry operator generates a one‐dimensional zigzag chain of octahedral Fe^II centers with μ₂‐TCNQ²⁻ bridges. A methanol solvent molecule forms hydrogen bonds to one of the terminal N atoms of the bridging TCNQ²⁻ dianion. To the best of our knowledge, these are the first examples of one‐dimensional coordination polymers forming from cis coordination of two TCNQ ligands to octahedral metal centers.     

catena‐Poly[[(2,2′‐diamino‐4,4′‐bithiazole){μ3‐cis‐N‐(2‐carboxylatophenyl)‐N′‐[3‐(dimethylamino)propyl]oxamidato(3−)}dicopper(II)] nitrate 0.6‐hydrate]

The title complex, {[Cu₂(C₁₄H₁₆N₃O₄)(C₆H₆N₄S₂)]NO₃·0.6H₂O}_n, is a one‐dimensional copper(II) coordination polymer bridged by cis‐oxamide and carboxylate groups. The asymmetric unit is composed of a dinuclear copper(II) cation, [Cu₂(dmapob)(dabt)]⁺ {dmapob is N‐(2‐carboxylatophenyl)‐N′‐[3‐(dimethylamino)propyl]oxamidate and dabt is 2,2′‐diamino‐4,4′‐bithiazole}, one nitrate anion and one partially occupied site for a solvent water molecule. The two Cu^II ions are located in square‐planar and square‐pyramidal coordination environments, respectively. The separations of the Cu atoms bridged by oxamide and carboxylate groups are 5.2053 (3) and 5.0971 (4) Å, respectively. The complex chains are linked by classical hydrogen bonds to form a layer and then assembled by π–π stacking interactions into a three‐dimensional network. The influence of the terminal ligand on the structure of the complex is discussed.     

Piperazine‐1,4‐diium–2,4‐dinitrophenolate–water (1/2/2)

In the title 1/2/2 adduct, C₄H₁₂N₂²⁺·2C₆H₃N₂O₅^?·2H₂O, the dication lies on a crystallographic inversion centre and the asymmetric unit also has one anion and one water mol­ecule in general positions. The 2,4‐di­nitro­phenolate anions and the water mol­ecules are linked by two O—H?O and two C—H?O hydrogen bonds to form molecular ribbons, which extend along the b direction. The piperazine dication acts as a donor for bifurcated N—H?O hydrogen bonds with the phenolate O atom and with the O atom of the o‐nitro group. Six symmetry‐related molecular ribbons are linked to a piperazine dication by N—H?O and C—H?O hydrogen bonds.     

Bis(3,5‐di­methyl­pyrazole‐κN2)silver(I) nitrate

The two independent bis(3,5‐di­methyl­pyrazole)silver(I) cations in crystalline [Ag(C₅H₇N₂)₂]NO₃ display N—Ag—N angles of 175.51 (14) and 174.44 (13)°, and an average Ag—N distance of 2.124 (5) Å. The nitrate anion is situated between [Ag(C₅H₇N₂)₂]⁺ units and interacts via hydrogen bonds with the NH groups. The two 3,5‐di­methyl­pyrazole ligands are trans about the silver center. Only a small deviation from linearity is observed in the coordination around silver.     

Kinetics and Mechanism of the Reaction of a Ruthenium(VI) Nitrido Complex with HSO3− and SO32− in Aqueous Solution

The kinetics and mechanism of the reaction of S^IV (SO₃^2?+HSO₃^?) with a ruthenium(VI) nitrido complex, [(L)Ru^VI(N)(OH₂)]⁺ (Ru^VIN, L=N,N′‐bis(salicylidene)‐o‐cyclohexyldiamine dianion), in aqueous acidic solutions are reported. The kinetic results are consistent with parallel pathways involving oxidation of HSO₃^? and SO₃^2? by Ru^VIN. A deuterium isotope effect of 4.7 is observed in the HSO₃^? pathway. Based on experimental results and DFT calculations the proposed mechanism involves concerted N?S bond formation (partial N‐atom transfer) between Ru^VIN and HSO₃^? and H⁺ transfer from HSO₃^? to a H₂O molecule.     

Dianionic Titanyl and Vanadyl (Cation+)2[MIVO(Pc4−)]2− Phthalocyanine Salts Containing Pc4− Macrocycles

In this study, the titanyl and vanadyl phthalocyanine (Pc) salts (Bu₄N⁺)₂[M^IVO(Pc^4?)]^2? (M=Ti, V) and (Bu₃MeP⁺)₂[M^IVO(Pc^4?)]^2? (M=Ti, V) with [M^IVO(Pc^4?)]^2? dianions were synthesized and characterized. Reduction of M^IVO(Pc^2?) carried out with an excess of sodium fluorenone ketyl in the presence of Bu₄N⁺ or Bu₃MeP⁺ is exclusive to the phthalocyanine centers, forming Pc^4? species. During reduction, the metal +4 charge did not change, implying that Pc is an non‐innocent ligand. The Pc negative charge increase caused the C?N(pyr) bonds to elongate and the C?N(imine) bonds to alternate, thus increasing the distortion of Pc. Jahn–Teller effects are significant in the [eg(π*)]² dianion ground state and can additionally distort the Pc macrocycles. Blueshifts of the Soret and Q‐bands were observed in the UV/Vis/NIR when M^IVO(Pc^2?) was reduced to [M^IVO(Pc ^{. 3?})] ^{. ?} and [M^IVO(Pc^4?)]^2?. From magnetic measurements, [Ti^IVO(Pc^4?)]^2? was found to be diamagnetic and (Bu₄N⁺)₂[V^IVO(Pc^4?)]^2? and (Bu₃MeP⁺)₂[V^IVO(Pc^4?)]^2? were found to have magnetic moments of 1.72–1.78 μ_B corresponding to an S=1/2 spin state owing to V^IV electron spin. As a result, two latter salts show EPR signals with V^IV hyperfine coupling.     

Bis[N,N′‐(2‐chlorobenzylidene)ethylenediamine‐κ2N,N′]copper(I) dichloridocuprate(I) acetonitrile solvate

The 1:1 adduct of N,N′‐bis(2‐chlorobenzylidene)ethylenediamine (cb₂en) with copper(I) chloride proves to be an ionic compound with Cu^I‐centred cations and anions, [Cu(C₁₆H₁₄Cl₂N₂)₂][CuCl₂]·CH₃CN. In the cation, the Cu^I atom has a flattened tetrahedral coordination geometry, with a small bite angle for the chelating ligands, which form a double‐helical arrangement around the metal centre. The anion is almost linear, as expected. The packing of the cations involves intermolecular π–π interactions, which lead to columns of translationally related cations along the shortest unit‐cell axis, with anions and solvent molecules in channels between them.     

Retention of the Zn−Zn bond in [Ge9Zn−ZnGe9]6− and Formation of [(Ge9Zn)−(Ge9)−(ZnGe9)]8− and Polymeric [−(Ge9Zn)2−−]

Reactions of Zn^I₂L₂ (where L=[HC(PPh₂NPh)]⁻) with solutions of the Zintl phase K₄Ge₉ in liquid ammonia lead to retention of the Zn−Zn bond and formation of the anion [(η⁴‐Ge₉)Zn−Zn(η⁴‐Ge₉)]⁶⁻, representing the first complex with a Zn−Zn unit carrying two cluster entities. The trimeric anion [(η⁴‐Ge₉)Zn{μ₂(η¹:η¹Ge₉)}Zn(η⁴‐Ge₉)]⁸⁻ forms as a side product, indicating that oxidation reactions also take place. The reaction of Zn₂Cp*₂ (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) with K₄Ge₉ in ethylenediamine yielded the linear polymeric unit {[Zn[μ₂(η⁴:η¹Ge₉)]}²⁻ with the first head‐to‐tail arrangement of ten‐atom closo ‐clusters. All anions were obtained and structurally characterized as [A (2.2.2‐crypt)]⁺ salts (A =K, Rb). Copious computational analyses at a DFT‐PBE0/def2‐TZVPP/PCM level of theory confirm the experimental structures and support the stability of the two hypothetical ten vertex cluster fragments closo ‐[Ge₉Zn]²⁻ and (paramagnetic) [Ge₉Zn]³⁻.     

(8‐Dimethylamino‐1‐naphthyl)dimethylammonium 3‐carboxy‐1,4,5,‐6,7,7‐hexachlorobicyclo[2.2.1]hept‐5‐ene‐2‐carboxylate hydrate

The structure of the title compound, C₁₄H₁₉N₂⁺·C₉H₃Cl₆O₄^?·H₂O, consists of singly ionized 1,4,5,6,7,7‐hexachlorobicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboxylic acid anions and protonated 1,8‐bis(dimethylamino)naphthalene cations. In the (8‐dimethylamino‐1‐napthyl)dimethylammonium cat­ion, a strong disordered intramolecular hydrogen bond is formed with N?N = 2.589 (3) Å. The geometry and occupancy obtained in the final restrained refinement suggest that the disordered hydrogen bond may be asymmetric. Water mol­ecules link the anion dimers into infinite chains via hydrogen bonding.     

Structural studies of (prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine hetero‐scorpionate copper complexes

The structures of five compounds consisting of (prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine complexed with copper in both the Cu^I and Cu^II oxidation states are presented, namely chlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(I) 0.18‐hydrate, [CuCl(C₁₅H₁₇N₃)]·0.18H₂O, (1), catena‐poly[[copper(I)‐μ₂‐(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ⁵N,N′,N′′:C²,C³] perchlorate acetonitrile monosolvate], {[Cu(C₁₅H₁₇N₃)]ClO₄·CH₃CN}_n, (2), dichlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II) dichloromethane monosolvate, [CuCl₂(C₁₅H₁₇N₃)]·CH₂Cl₂, (3), chlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II) perchlorate, [CuCl(C₁₅H₁₇N₃)]ClO₄, (4), and di‐μ‐chlorido‐bis({(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II)) bis(tetraphenylborate), [Cu₂Cl₂(C₁₅H₁₇N₃)₂][(C₆H₅)₄B]₂, (5). Systematic variation of the anion from a coordinating chloride to a noncoordinating perchlorate for two Cu^I complexes results in either a discrete molecular species, as in (1), or a one‐dimensional chain structure, as in (2). In complex (1), there are two crystallographically independent molecules in the asymmetric unit. Complex (2) consists of the Cu^I atom coordinated by the amine and pyridyl N atoms of one ligand and by the vinyl moiety of another unit related by the crystallographic screw axis, yielding a one‐dimensional chain parallel to the crystallographic b axis. Three complexes with Cu^II show that varying the anion composition from two chlorides, to a chloride and a perchlorate to a chloride and a tetraphenylborate results in discrete molecular species, as in (3) and (4), or a bridged bis‐μ‐chlorido complex, as in (5). Complex (3) shows two strongly bound Cl atoms, while complex (4) has one strongly bound Cl atom and a weaker coordination by one perchlorate O atom. The large noncoordinating tetraphenylborate anion in complex (5) results in the core‐bridged Cu₂Cl₂ moiety.     

A mixed‐valence manganese(III)–manganese(IV) di‐μ‐oxo complex, [(cyclam)MnO]2(ClO4)2(NO3)

The title dinuclear di‐μ‐oxo‐bis­[(1,4,8,11‐tetra­aza­cyclo­tetra­decane‐κ⁴N)­manganese(III,IV)] diperchlorate nitrate complex, [Mn₂O₂(C₁₀H₂₄N₄)₂](ClO₄)₂(NO₃) or [(cyclam)Mn­O]₂(ClO₄)₂(NO₃), was self‐assembled by the reaction of Mn²⁺ with 1,4,8,11‐tetra­aza­cyclo­tetra­decane in aqueous media. The structure of this compound consists of a centrosymmetric binuclear [(cyclam)MnO]³⁺ unit, two perchlorate anions and one nitrate anion. While the low‐temperature electron paramagnetic resonance spectra show a typical 16‐line signal for a di‐μ‐oxo Mn^III/Mn^IV dimer, the magnetic susceptibility studies also confirm a characteristic antiferromagnetic coupling between the electronic spins of the Mn^IV and Mn^III ions.     

catena‐Poly[[bis(μ‐2‐sulfonatobenzoato)bis[triaquagadolinium(III)]]‐μ‐oxalato]

The asymmetric unit of the title coordination polymer, [Gd₂(C₇H₄O₅S)₂(C₂O₄)(H₂O)₆]_n or [Gd(2‐SB)(ox)_0.5(H₂O)₃]_2n (2‐SB is 2‐sulfonatobenzoate and ox is oxalate), (I), consists of one Gd^III ion, one 2‐SB anion, three coordinated water molecules and one half of an ox ligand. The ox ligand is located on a crystallographic inversion centre. The Gd^III centre shows a distorted tricapped trigonal–prismatic coordination formed by nine O atoms from two 2‐SB anions, one ox ligand and three coordinated water molecules. The carboxylate and sulfonate groups of the 2‐SB anions adopt μ₂‐η¹:η² and μ₁‐η⁰:η⁰:η¹ coordination modes to link two Gd^III ions, generating a centrosymmetric binuclear [Gd₂(2‐SB)₂(H₂O)₆]²⁻ subunit. The ox ligand acts as a bridge, linking the binuclear [Gd₂(2‐SB)₂(H₂O)₆]²⁻ subunits into a one‐dimensional chain structure parallel to the b axis. Furthermore, extensive O—H...O hydrogen bonds connect the chains into a three‐dimensional supramolecular architecture.