Hydrate isomerism in [Cu(en)2(H2O)1.935]2[Fe(CN)6]·4H2O

The title compound, bis[di­aqua­bis­(ethyl­enedi­amine‐κ²N,N′)copper(II)­] hexa­cyano­iron(II) tetrahydrate, [Cu(C₂H₈N₂)₂(H₂O)_1.935]₂[Fe(CN)₆]·4H₂O, was crystallized from an aqueous reaction mixture initially containing CuSO₄, K₃[Fe(CN)₆] and ethyl­enedi­amine (en) in a 3:2:6 molar ratio. Its structure is ionic and is built up of two crystallographically different cations, viz. [Cu(en)₂(H₂O)₂]²⁺ and [Cu(en)₂(H₂O)_1.87]²⁺, there being a deficiency of aqua ligands in the latter, [Fe(CN)₆]⁴⁻ anions and disordered solvent water mol­ecules. All the metal atoms lie on centres of inversion. The Cu atom is octahedrally coordinated by two chelate‐bonded en mol­ecules [mean Cu—N = 2.016 (2) Å] in the equatorial plane, and by axial aqua ligands, showing very long distances due to the Jahn–Teller effect [mean Cu—O = 2.611 (2) Å]. In one of the cations, significant underoccupation of the O‐atom site is observed, correlated with the appearance of a non‐coordinated water mol­ecule. This is interpreted as the partial contribution of a hydrate isomer. The [Fe(CN)₆]⁴⁻ anions form quite regular octahedra, with a mean Fe—C distance of 1.913 (2) Å. The dominant intermolecular interactions are cation–anion O—H⋯N hydrogen bonds and these inter­actions form layers parallel to (001).     

Low‐dimensional compounds containing cyano groups. XVI. (Dicyanamido‐κN1)bis(1,10‐phenanthroline‐κ2N,N′)copper(II) tetrafluoridoborate

The title compound, [Cu{N(CN)₂}(C₁₂H₈N₂)₂]BF₄, was prepared as part of our study of the shape of coordination polyhedra in five‐coordinated copper(II) complexes. Single‐crystal X‐ray analysis reveals that the structure consists of [Cu{N(CN)₂}(phen)₂]⁺ cations (phen is 1,10‐phenanthroline) and BF₄⁻ anions. The Cu centre is five‐coordinated in a distorted trigonal bipyramidal manner by four N atoms of two phen ligands and one N atom of a dicyanamide anion, which is coordinated in the equatorial plane at a distance of 1.996 (2) Å. The two axial Cu—N_phen distances have similar values [average 1.994 (6) Å] and are shorter than the two equatorial Cu—N_phen bonds [average 2.09 (6) Å]. This work demonstrates the effect of ligand rigidity on the shape of coordination polyhedra in five‐coordinated copper(II) complexes.     

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.     

The three‐dimensional coordination polymer tetra­ethyl­ammonium (ethyl­ene­di­amine)­cadmium(II) hexa­cyano­ferrate(III), (Et4N){[Cd(en)]4[Fe(CN)6]3}

The title compound, tetra­ethyl­ammonium dodeca‐μ‐cyano‐hexa­cyano­tetrakis­(ethyl­ene­di­amine)­tetra­cadmium(II)­tri­fer­rate(III), (C₈H₂₀N)[Cd₄Fe₃(CN)₁₈(C₂H₈N₂)₄], was pre­pared from a reaction mixture containing CdCl₂, K₃[Fe(CN)₆], ethyl­ene­di­amine (en) and [Et₄N]Br in a 1:1:3:1 molar ratio. The crystal structure consists of a negatively charged three‐dimensional framework of {[Cd(en)]₄[Fe(CN)₆]₃} anions, with [Et₄N]⁺ cations located in the cavities of the framework. The Cd atom is octahedrally coordinated by one disordered chelating en mol­ecule [mean Cd—N = 2.35 (3) Å] and four N‐­bonded bridging cyano groups [Cd—N distances are in the range 2.283 (2)–2.441 (2) Å]. There are two crystallographically independent [Fe(CN)₆]³⁻ anions in the structure and in each the Fe atom lies on a twofold axis. In the first [mean Fe—C = 1.941 (5) Å], all the cyano groups are bridging ligands, while in the second [mean Fe—C = 1.945 (2) Å], there are two terminal cyano ligands in trans positions. The Cd—N—C angles range from 128.6 (2) to 172.8 (2)°.     

Low‐dimensional compounds containing cyano groups. X. (Dicyan­amido‐κN1)­bis(1,10‐phenanthroline‐κ2N,N′)copper(II) perchlorate

The title compound, [Cu(C₂N₃)(C₁₂H₈N₂)₂]ClO₄, represents a relatively rare class of compounds with dicyan­amide coordinated in a monodentate manner. The structure is formed by the [Cu{N(CN)₂}(phen)₂]⁺ complex cation (phen is 1,10‐phenanthroline) and an uncoordinated ClO₄⁻ anion. The Cu atom is five‐coordinate, with a slightly distorted trigonal–bipyramidal environment. The dicyan­amide ligand is coordinated through one nitrile N atom in the equatorial plane, at a distance of 2.033 (6) Å from the metal. The two axial Cu—N distances are similar [mean 1.999 (4) Å] and are substantially shorter than the remaining two equatorial Cu—N bonds [mean 2.087 (1) Å].     

Acetato(N‐phenylpyridine‐2‐carboxamidato‐κ2N,N)(N‐phenylpyridine‐2‐carboxamide‐κ2N1,O)copper(II)

The title complex, [Cu(C₁₂H₉N₂O)(C₂H₃O₂)(C₁₂H₁₀N₂O)], is a neutral Cu^II complex with a primary N₃O₂ coordination sphere. The Cu centre coordinates to both a deprotonated and a neutral molecule of N‐phenylpyridine‐2‐carboxamide and also to an acetate anion. The coordination around the metal centre is asymmetric, the deprotonated ligand providing two N donor atoms [Cu—N = 1.995 (2) and 2.013 (2) Å] and the neutral ligand providing one N and one O donor atom to the coordination environment [Cu—N = 2.042 (2) Å and Cu—O = 2.2557 (19) Å], the fifth donor being an O atom of the acetate ion [Cu—O = 1.9534 (19) Å]. The remaining O atom from the acetate ion can be considered as a weak donor atom [Cu—O = 2.789 (2) Å], conferring to the Cu complex an asymmetric octahedral geometry. The crystal structure is stabilized by intermolecular N—H...O, C—H...O and C—H...π interactions.     

阴离子导向组装：两个具有不同阳离子的多维Ag(I)配合物的晶体结构

Assembly of [Ag（CN）2]^- units with M（Ⅱ）-diamine complex cations [Cu（LN-N）2]^2＋, where LN-N represents L2-diaminopropane （pn） and ethylenediamine （en）, afforded two complexes, [Cu（pn）2][Ag2（CN）4] （1） and [Cu（en）2][Ag3（CN）5] （2）, which were characterized by elemental analysis, IR, UV-Vis and ESR spectra. Single crystal X-ray analyses show that these complexes have 2D and 3D architectures through silver-silver interactions and other weak interactions. The luminescence behaviors of the two complexes were also studied by means of emission spectra.     

The one‐dimensional structure of Cu(dmen)2Pd(CN)4 (dmen is N,N‐di­methyl­ethyl­enedi­amine)

The title compound, catena‐poly­[[μ‐cyano‐1:2κ²C:N‐dicyano‐1κ²C‐bis(N,N‐di­methyl­ethyl­enedi­amine‐2κ²N,N′)­pallad­ium(II)­copper(II)]‐μ‐cyano‐1:2′κ²C:N], [CuPd(CN)₄(C₄H₁₂N₂)₂]_n, consists of infinite quasi‐linear chains with all metal positions on centers of symmetry. The paramagnetic [Cu(dmen)₂]²⁺ cations are linked by diamagnetic [Pd(CN)₄]²⁻ anions via bridging cyano groups, which occupy trans positions in both cation and anion, giving rise to 2,2‐TT‐type chains. The coordination polyhedron of the paramagnetic Cu atom is an octahedron exhibiting typical elongation due to the Jahn–Teller effect, with two longer Cu—N([triple‐bond]C) bonds in the axial positions [2.5528 (13) Å] and four shorter Cu—N_dmen bonds (dmen is N,N‐dimethylethylenediamine) in the equatorial plane [1.9926 (11) and 2.1149 (12) Å]. The Cu—N[triple‐bond]C angle is 138.03 (12)°. Neighboring chains form weak N—H⋯NC hydrogen bonds.     

Low‐dimensional compounds containing cyano groups. II. catena‐Poly[[(2,2′‐bipyridine‐κ2N:N′)(dicyanamido‐κN)copper(II)]‐μ‐dicyanamido‐κ2N:N′]

The crystal structure of the title compound, [Cu(C₂N₃)₂(C₁₀H₈N₂)]_n, is formed by neutral zigzag chains of the [–NC–N–CN–Cu{(bpy)N(CN)₂}–NC–N–CN–] type run­ning along the c axis (bpy is 2,2′‐bi­pyridine). The Cu atoms in the chains are pentacoordinated in the form of a distorted tetragonal pyramid, with a CuN₅ chromophore. The coordination sites are occupied by two N atoms of one bpy mol­ecule in the basal plane [Cu—N 2.018 (4) and 2.025 (2) Å] and by three terminal N atoms of two dicyan­amide ligands. One of the dicyan­amide ligands is coordinated in a monodentate fashion through a nitrile N atom in the basal plane [Cu—N 1.963 (4) Å]. The second acts as an end‐to‐end bridging ligand to a neighbouring Cu atom and is coordinated by one nitrile N atom in the basal plane [Cu—N 2.001 (2) Å], while the second nitrile N atom occupies the apical position [Cu—N 2.159 (2) Å] and originates from the bridge connecting another Cu atom. The shortest intrachain Cu?Cu distance is 8.212 (1) Å, as a consequence of the large bridging ligand, whereas the minimum interchain distance between Cu atoms is only 5.77 (7) Å, because of the interdigitation of the chains.     

Low‐dimensional compounds containing cyano groups. I. catena‐Poly[[[dicyanoargentato(I)‐κN]bis(4‐methylpyridine‐κN)copper(II)]‐μ‐dicyanoargentato(I)‐κ2N:N′]

The structure of the title compound, [Cu(C₆H₇N)₂{Ag(CN)₂}₂]_n, is made up of neutral zigzag chains of [–NC–Ag–CN–Cu(4‐Mepy)₂{Ag(CN)₂}–NC–Ag–CN–] (4‐Mepy is 4‐methyl­pyridine). Neighbouring chains are linked by weak argentophilic interactions, with Ag?Ag distances of 3.2322 (12) Å. The Cu atom, which lies on a twofold rotation axis, is pentacoordinated by one monodentate Ag(CN)₂^? anion [Cu—N 1.985 (3) Å], the atoms of which lie on the same rotation axis, and by bridging di­cyano­argentate anions [2 × Cu—N 2.0827 (19) Å], with Ag atoms on inversion centres. The coordination polyhedron is completed by two 4‐Mepy mol­ecules [2 × Cu—N 2.038 (2) Å], which occupy the axial positions of a distorted trigonal bipyramid.     

Low‐dimensional compounds containing cyano groups. XII.)copper(II) perchlorate

The title compound, [Cu(C₂N₃)(C₃H₁₀N₂)₂]ClO₄, is made up of [Cu(tn)₂{N(CN)₂}]⁺ complex cations (tn is 1,3‐diamino­propane) and ClO₄⁻ anions. The Cu^II atom is coordinated by four N atoms of two equatorial tn ligands, with an average distance of 2.041 (7) Å, and one nitrile N atom of the dicyanamide anion in an axial position, at a distance of 2.236 (3) Å, in a manner approaching square‐planar coordination geometry. The complex has C_s symmetry, with the mirror plane lying through the central C atoms of both tn ligands and the dca ligand. The ClO₄⁻ anion might be considered as very weakly coordinated in the opposite axial position [Cu—O = 2.705 (3) Å], thus completing the Cu^II coordination to asymmetric elongated octa­hedral (4+1+1*). The Cu atom and the perchlorate anion both lie on mirror planes.     

Cu2(dien)2Ag5(CN)9 containing the one‐dimensional polymeric cation [Cu(dien)Ag(CN)2]nn+ and the unusual [Ag2(CN)3]− anion (dien is diethylenetriamine)

From the 1:1 system of [Cu(dien)₂](NO₃)₂ and K[Ag(CN)₂] in water (dien is diethyl­enetri­amine, C₄H₁₃N₃), the novel compound catena‐poly­[bis­[[μ‐cyano‐1:2κ²C:N‐diethyl­enetri­amine‐2κ³N‐copper(II)silver(I)]‐μ‐cyano‐1:2′κ²C:N] di­cyano­silver(I) tri­cyanodisilver(I)], [CuAg(CN)₂(dien)]₂[Ag(CN)₂][Ag₂(CN)₃], has been isolated. The structure is formed from positively charged [–Cu(dien)–NC–Ag–CN–]_nⁿ⁺ chains and two isolated centrosymmetric [Ag(CN)₂]^? and [Ag₂(CN)₃]^? anions. In the cationic chains, the Cu atoms are linked by bridging di­cyano­argentate groups, and the deformed square‐pyramidal coordination polyhedron of the Cu^II cation is formed from a tridentate chelate‐like bonded dien ligand and two N‐bonded bridging cyano groups. One of the bridging cyano groups occupies the apical (ap) position [mean Cu—­N_eq = 2.02 (2) Å, and Cu—N_ap = 2.170 (3) Å; eq is equatorial]. Short argentophilic interactions in the range 3.16–­3.30 Å are present in the crystal structure.     

A three‐dimensional heterometallic CuI/VIV 1,2‐bis(1,2,4‐triazol‐4‐yl)ethane framework: a new insight into the structure of vanadium oxyfluoride coordination hybrids

The bitopic ligand 1,2‐bis(1,2,4‐triazol‐4‐yl)ethane (tr₂eth) provides an unprecedented short‐distance N¹:N²‐triazole bridging of Cu^I and V^IV ions in poly[bis[μ₄‐1,2‐bis(1,2,4‐triazol‐4‐yl)ethane]di‐μ₂‐fluorido‐tetrafluoridodi‐μ₂‐oxido‐dicopper(I)divanadium(IV)], [Cu₂V₂F₆O₂(C₆H₈N₆)₂]_n. The Cu^I ions and tr₂eth linkers afford a two‐dimensional square‐grid topology involving centrosymmetric (tr)Cu(μ‐tr)₂Cu(tr) [tr is triazole; Cu—N = 1.9525 (16)–2.0768 (18) Å] binuclear net nodes, which are expanded in a third dimension by centrosymmetric [V₂O₂F₆]²⁻ pillars. The concerted μ‐tr and μ‐O bridging between the Cu^I and V^IV ions allows a multi‐centre accommodation of the vanadium oxyfluoride moiety on a cationic Cu/tr₂eth matrix [Cu—O = 2.1979 (15) Å and V—N = 2.1929 (17) Å]. The distorted octahedral coordination of [VONF₄] is completed by two terminal and two bridging F⁻ ions [V—F = 1.8874 (14)–1.8928 (13) and 2.0017 (13)–2.1192 (12) Å, respectively]. The resulting three‐dimensional framework has a primitive cubic net topology and adopts a threefold interpenetration.     

Bis­[bis­(pyrimidin‐2‐yl‐κN)­amine](dicyan­amido‐κN1)(tri­fluoro­methanesulfonato‐κO)copper(II) ethanol hemisolvate forms a hydrogen‐bonded chain

In the crystal structure of [Cu(CF₃SO₃)(C₂N₃)(C₈H₇N₅)₂]·0.5C₂H₆O, the Cu^II atom adopts a distorted octahedral geometry, with the basal plane formed by two N atoms of one dipyrimidinyl­amine ligand, one N atom of the second pyrimidine ligand and a nitrile N atom of the dicyan­amide anion [Cu—N = 1.972 (2)–2.021 (2) Å]. The apical positions are occupied by an N atom of the second ligand [Cu—N = 2.208 (2) Å], and an O atom of the tri­fluoro­methane­sulfonate anion [Cu—O = 2.747 (2) Å] at a semi‐coordination distance. Pairs of inversion‐related N—H⋯N hydrogen bonds of the so‐called Watson–Crick type, augmented by two C—H⋯N contacts, link adjacent complexes into an infinite one‐dimensional chain running in the [101] direction.     

Poly[tetraamminecopper(II) bis[tris(μ2‐cyanido‐κ2C,N)dicuprate(I)]]: a unique CuI–CuII mixed‐valence complex containing anionic cuprous cyanide layers and [Cu(NH3)4]2+ cations

The title compound, {[Cu(NH₃)₄][Cu(CN)₃]₂}_n, features a Cu^I–Cu^II mixed‐valence CuCN framework based on {[Cu₂(CN)₃]⁻}_n anionic layers and [Cu(NH₃)₄]²⁺ cations. The asymmetric unit contains two different Cu^I ions and one Cu^II ion which lies on a centre of inversion. Each Cu^I ion is coordinated to three cyanide ligands with a distorted trigonal–planar geometry, while the Cu^II ion is ligated by four ammine ligands, with a distorted square‐planar coordination geometry. The interlinkage between Cu^I ions and cyanide bridges produces a honeycomb‐like {[Cu₂(CN)₃]⁻}_n anionic layer containing 18‐membered planar [Cu(CN)]₆ metallocycles. A [Cu(NH₃)₄]²⁺ cation fills each metallocyclic cavity within pairs of exactly superimposed {[Cu₂(CN)₃]⁻}_n anionic layers, but there are no cations between the layers of adjacent pairs, which are offset. Pairs of N—H...N hydrogen‐bonding interactions link the N—H groups of the ammine ligands to the N atoms of cyanide ligands.     

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].     

Bis(4‐aminopyridine)silver(I) nitrate and tris(2,6‐diaminopyridine)silver(I) nitrate

The bis(4‐aminopyridine)silver(I) cation in [Ag(C₅H₆N₂)₂]NO₃ has the Ag atom on a twofold axis and displays an N—Ag—N angle of 174.43 (15)° and an Ag—N distance of 2.122 (3) Å. The two ligands are planar and the angle between the two ligand planes is 79.45 (9)°. The pyridine rings are stacked in piles with an interplanar distance of 3.614 (5) Å, a distance that strongly suggests that pyridine π–π interactions have an appreciable importance with respect to the non‐bonded crystal organization. The tris(2,6‐diaminopyridine)­silver(I) cation in [Ag(C₅H₇N₃)₃]NO₃ has Ag—N distances of 2.243 (2), 2.2613 (17) and 2.4278 (18) Å, and N—Ag—N angles of 114.33 (7), 134.91 (7) and 114.33 (7)°. The Ag⁺ ion is situated 0.1531 (2) Å from the plane defined by the three pyridine N atoms.     

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.     

Low‐dimensional compounds containing cyano groups. VI.

The title compound, [Cu₂(C₄H₁₂N₂)₂{Ag(CN)₂}₄(NH₃)]·2H₂O or [Ag₄Cu₂(CN)₈(C₄H₁₂N₂)₂(NH₃)]·2H₂O, contains two crystallographically different Cu^II atoms lying on twofold axes. The first Cu atom is hexacoordinated in the form of an elongated tetragonal bipyramid and is part of a plane in which Cu atoms are connected by two bridging di­amino­butane mol­ecules [Cu—N = 2.033 (4) Å] and two di­cyano­argentate anions [Cu—N = 2.622 (6) Å]. The ammine ligand stands perpendicular to this plane [Cu—N = 2.011 (6) Å] in a trans position to it. Another [Ag(CN)₂]⁻ anion connects the hexacoordinated Cu atom [Cu—N = 1.997 (8) Å] with the second Cu atom [Cu—N = 2.026 (7) Å], which is pentacoordinated in the form of a slightly distorted trigonal bipyramid by two monodentate di­cyano­argetate anions [Cu—N = 2.040 (5) Å]. The axial positions are occupied by two bridging di­amino­butane mol­ecules [Cu—N = 2.011 (4) Å] that connect the Cu atoms into chains parallel to the above plane. The water mol­ecules remain uncoordinated and thus a unique combination of two‐ and one‐dimensional structures is formed.     

A mixed‐valence iron complex of the antitumour drug 6‐mercaptopurine: tris(6‐mercaptopurine)iron(II) tetrachloroferrate(III) chloride

Single crystals of the title complex, tris(1,6‐di­hydro‐9H‐purine‐6‐thione‐N⁷,S)­iron(II) tetra­chloro­ferrate(III) chloride, [Fe(C₅H₄N₄S)₃][FeCl₄]Cl, were grown on the surface of solid 6‐mercaptopurine monohydrate pellets in a solution of iron(III) chloride. The solution of the hexagonal structure required the application of twin refinement techniques. All the component ions lie on threefold rotation axes. The complex contains distorted octahedral [Fe(C₅H₄N₄S)₃]²⁺ cations with three N7/S6‐chelating neutral 6‐mercaptopurine ligands, tetrahedral [FeCl₄]^? anions with a mean Fe—Cl distance of 2.189 (1) Å, and free chloride ions.