Potassium carbamoyldi­cyano­methanide

The crystal structure of the title compound, K[(CN)₂CC(O)NH₂)] or K⁺·C₄H₂N₃O⁻, conventionally abbreviated as Kcdm, where cdm is carbamoyldi­cyano­methanide, is described. The bond lengths and angles of the cdm cation are comparable to those reported previously for [M(cdm)₂(H₂O)₄]·2H₂O (M = Ni, Mn and Co). The K atoms are coordinated to four nitrile N atoms and two carbonyl O atoms in a distorted trigonal prismatic fashion, with two further N atoms semicoordinated through the centers of two prism side faces. This coordination leads to the formation of mixed anion–cation sheets parallel to the ab plane, which are joined together via hydrogen‐bonding interactions. The cdm anion is potentially useful for the formation of transition metal coordination polymers, in which magnetic superexchange could occur through a bidentate cdm bridge. Kcdm provides a model compound by which the molecular geometry of the cdm anion can be analyzed.     

Di­aqua­bis(1,10‐phenanthroline‐κ2N,N′)­manganese(II) thiodiglycolate bis(1,10‐phenanthroline‐κ2N,N′)(thiodiglycolato‐κ2O,O′)­manganese(II) tridecahydrate

The title compound, [Mn(C₁₂H₈N₂)₂(H₂O)₂](C₄H₄O₄S)·[Mn(C₄H₄O₄S)(C₁₂H₈N₂)₂]·13H₂O, contains one dianion of thio­diglycolic acid (tdga²⁻) and two independent man­ganese(II) moieties, viz. [Mn(phen)₂(H₂O)₂]²⁺ and [Mn(tdga)(phen)₂], where phen is 1,10‐phenanthroline. The Mn^II atoms are octahedrally coordinated by four N atoms of two bidentate phen ligands [Mn—N = 2.240 (2)–2.3222 (19) Å] and either two water O atoms or two tdga carboxyl O atoms [Mn—O = 2.1214 (17)–2.1512 (17) Å]. The tdga ligand chelates as an O,O′‐bidentate ligand, forming an eight‐membered ring with one Mn atom. The free tdga²⁻ dianion is hydrogen bonded to an [Mn(phen)₂(H₂O)₂]²⁺ ion, with O⋯O distances of 2.606 (2) and 2.649 (2) Å. The crystal structure is further stabilized by an extensive network of hydrogen bonds involving 13 water mol­ecules.     

Two furo­pyridine complexes of nickel(II) iso­thio­cyanate

Pyridine fused with a furan ring (fupy), and its di­methyl derivative, have been used for the first time as ligands to synthesize potentially new Werner clathrates. The extended aromatic system of pyridine‐like ligands influences considerably the molecular structure of prepared nickel complexes. The molecular structure of tetrakis­(furo­[3,2‐c]­pyridine)­bis(iso­thio­cyanato)­nickel(II) tetra­hydro­furan (THF) solvate, [Ni(NCS)₂(C₇H₅NO)₄]·C₄H₈O or [Ni(NCS)₂(fupy)₄]·THF, (I), reveals a `four‐blade propeller' arrangement of ligands, with the angles between the fupy planes and the basal octahedron plane spanning the range 38.7–55.3°. These angles are much larger (69.9–78.8°) in the centrosymmetric complex tetrakis(2,3‐di­methyl­furo­[3,2‐c]­pyridine)­bis­(iso­thio­cyanato)nickel(II) 6.6‐hydrate, [Ni(NCS)₂(C₉H₉NO)₄]·6.6H₂O or [Ni(NCS)₂(Me₂fupy)₄]·6.6H₂O, (II), in which crystallographically imposed inversion symmetry is present.     

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.     

Cobalt(II) and nickel(II) complexes of isoquinoline‐1‐carboxylate

trans‐Di­aqua­bis­(iso­quinoline‐1‐carboxyl­ato‐κ²N,O)­cobalt(II) dihydrate, [Co(C₁₀H₆NO₂)₂(H₂O)₂]·2H₂O, and trans‐di­aqua­bis­(iso­quinoline‐1‐carboxyl­ato‐κ²N,O)­nickel(II) dihydrate, [Ni(C₁₀H₆NO₂)₂(H₂O)₂]·2H₂O, contain the same isoquinoline ligand, with both metal atoms residing on a centre of symmetry and having the same distorted octahedral coordination. In the former complex, the Co—O(water) bond length in the axial direction is 2.167 (2) Å, which is longer than the Co—O(carboxylate) and Co—N bond lengths in the equatorial plane [2.055 (2) and 2.096 (2) Å, respectively]. In the latter complex, the corresponding bond lengths for Ni—O(water), Ni—O(carboxylate) and Ni—N are 2.127 (2), 2.036 (2) and 2.039 (3) Å, respectively. Both crystals are stabilized by similar stacking interactions of the ligand, and also by hydrogen bonds between the hydrate and coordinated water molecules.     

Copper(II) and zinc(II) complexes of pyridine‐2,6‐di­carboxyl­ic acid

The title compounds, bis­(pyridine‐2,6‐di­carboxyl­ato‐N,O,O′)copper(II) monohydrate, [Cu(C₇H₄NO₄)₂]·H₂O, andbis(pyridine‐2,6‐dicarboxylato‐N,O,O′)zinc(II) trihydrate, [Zn(C₇H₄NO₄)₂]·3H₂O, have distorted octahedral geometries about the metal centres. Both metal ions are bonded to four O atoms and two pyridyl‐N atoms from the two terdentate ligand mol­ecules, which are nearly perpendicular to each other. The copper(II) complex has twofold crystallographic symmetry and contains two different ligand mol­ecules, one of which is neutral and another doubly ionized. In contrast, the zinc(II) complex contains two identical singly ionized ligand mol­ecules. Both crystal structures are stabilized by O—H?O intermolecular hydrogen bonds between the complex and the water mol­ecules.     

Pb(II) and Mn(II) Coordination Compounds Involving 5,5′‐(1,4‐Phenylene)bis(1H‐tetrazole):Synthesis,Characterization, and Effect on Thermal Decomposition of Ammonium Perchlorate

Two coordination compounds [Pb₄(BDT)₃(OH)₂(H₂O)₄]·H₂O ( 1 ) and [Mn(H₂O)₆]·(HBDT)₂·2H₂O ( 2 ) [H₂BDT?5,5′‐(1,4‐phenylene)bis(1H‐tetrazole)] had been hydrothermally synthesized. 1 and 2 had been characterized by single‐crystal X‐ray diffraction, IR, elemental and thermal analyses. Structural analysis reveals that 1 exhibits 2D layer structure extended through BDT with two different coordination modes rings in transverse and vertical. 2 consists of [Mn(H₂O)₆]²⁺, free HBDT and water. In addition, 1 and 2 were explored as luminescent materials and additives to promote the thermal decomposition of ammonium perchlorate by differential scanning calorimetry.     

Aquachloro[N,N′‐ethylenebis(salicylideneiminato)]manganese(III)

The title compound, aqua­chloro{2,2′‐[1,2‐ethanediyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴O,N,N′,O′}manganese(III),[MnCl(C₁₆H₁₄N₂O₂)(H₂O)], is a neutral manganese(III) complex with a pseudo‐octahedral metal centre. The equatorial plane comprises the four donor atoms of the tetradentate Schiff base ligand [Mn—O 1.886 (4) and 1.893 (4) Å, and Mn—N 1.978 (5) and 1.982 (5) Å], with a water mol­ecule [Mn—O 2.383 (4) Å] and a Cl^? ligand [Mn—Cl 2.4680 (16) Å] completing the coordination sphere. The distorted geometry is highlighted by the marked displacement of the Mn^III ion out of the least‐squares plane of the four Schiff base donor atoms by 0.165 (2) Å. These monomeric Mn^III centres are then linked into a polymeric array via hydrogen bonds between the coordinated water mol­ecule and the phenolic O‐atom donors of an adjacent Mn^III centre [O—H?O 2.789 (5) and 2.881 (5) Å].     

Pseudo‐merohedrally twinned praseodymium hexa­cyano­ferrate(III) tetrahydrate

Crystals of the title compound, di­aqua­hexa‐μ‐cyano‐ferrate(III)­praseo­dym­ium(III) dihydrate, Pr[Fe(CN)₆]·4H₂O or [PrFe(CN)₆(H₂O)₂]·2H₂O, are twinned with three components. The Pr atom is coordinated by eight atoms, viz. six N and two symmetry‐related water O atoms. The Pr polyhedron (Pr has site symmetry m2m, Wyckoff position 4c) is linked to an FeC₆ octahedron (Fe located on a site with imposed 2/m symmetry, Wyckoff position 4b) through N atoms, forming an infinite array. The second (symmetry independent) water mol­ecule lies on a mirror plane, is not included in coordination and is weakly hydrogen bonded to N atoms.     

Bis(1,10‐phenanthroline‐N,N′)(thiosulfato‐O,S)­nickel(II)–water–methanol (1/0.92/1.4) and bis(2,2′‐bi­pyridyl‐N,N′)(thiosulfato‐O,S)nickel(II)–water–methanol (1/2/0.55)

The title compounds, [Ni(S₂O₃)­(C₁₂H₈N₂)₂]·­0.92H₂O·­1.4CH₄O and [Ni(S₂O₃)­(C₁₀H₈N₂)₂]·­2H₂O·­0.55CH₄O, are monomeric, containing nickel(II) in a distorted octahedral coordination environment provided by the four N atoms of two bidentate bipy or phen groups and one S and one O atom from a chelating thio­sulfate anion. The crystals are highly unstable outside their mother liquors and are stabilized in solution by a not fully determined number of water and methanol solvate mol­ecules. The phenanthroline structure includes two independent moieties related by a non‐crystallographic inversion center. The thio­sulfate anions display the usual S—O lengthening found when the anion acts in a bidentate mode.     

NaIn(CrO4)2·2H2O,the first indium(III) member of the kröhnkite family

Sodium indium(III) chromate(VI) dihydrate, NaIn(CrO₄)₂·2H₂O, synthesized from an aqueous solution at room temperature, is the first indium(III) member of the large family of compounds with kröhnkite [Na₂Cu^II(S^VIO₄)₂·2H₂O]‐type chains. The crystal structure is based on infinite octa­hedral–tetra­hedral [In(CrO₄)₂(H₂O)₂]⁻ chains along [010], linked via charge‐balancing Na⁺ cations. The slightly distorted InO₄(H₂O)₂ octa­hedra are characterized by a mean In—O distance of 2.125 Å. The CrO₄ tetra­hedra are strongly distorted (mean Cr—O = 1.641 Å). The Na atom shows an octa­hedral coordination, unprecedented among compounds with kröhnkite‐type chains. The NaO₆ octa­hedra share opposite edges with the InO₄(H₂O)₂ octa­hedra to form infinite [001] chains. The hydrogen bonds are of medium strength. NaIn(CrO₄)₂·2H₂O belongs to the structural type F2 in the classification of Fleck, Kolitsch & Hertweck [Z. Kristallogr. (2002), 217 , 435–443], and is isotypic with KAl(CrO₄)₂·2H₂O and MFe(CrO₄)₂·2H₂O (M = K, Tl or NH₄). All atoms are in special positions except one O atom.     

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).     

Two saccharinate complexes: [Mn(phen)2(sac)(H2O)]+·sac– and [Co(bipy)2(sac)(H2O)]+·sac–

The title saccharinate complexes, aqua[1,2‐benzisothiazol‐3(2H)‐onato 1,1‐dioxide‐N]bis(1,10‐phenanthroline‐N,N′)man­ganese(II) 1,2‐benz­isothia­zol‐3(2H)‐onate 1,1‐dioxide,[Mn(C₇H₄NO₃S)(C₁₂H₈N₂)₂(H₂O)](C₇H₄NO₃S), and aqua[1,2‐benz­iso­thiazol‐3(2H)‐onato 1,1‐dioxide‐N]­bis­(2,2′‐bi­pyri­dine‐N,N′)­cobalt(II) 1,2‐benz­iso­thia­zol‐3(2H)‐onate 1,1‐di­oxide, [Co­(C₇H₄NO₃S)­(C₁₀H₈N₂)₂­(H₂O)]­(C₇H₄NO₃S), have been prepared and their crystal structures determined at 150 K. The structure of the manganese complex consists of repeated alternating [Mn(phen)₂(sac)(H₂O)]⁺ cations and non‐coordinated saccharinate anions. The water molecule, bound to manganese as part of a slightly distorted octahedral arrangement, is hydrogen bonded to an O atom of the SO₂ group in the saccharinate counter‐ion. In contrast, the cobalt complex has one pseudo‐octahedral [Co(bipy)₂(sac)(H₂O)]⁺ cation, with the cobalt‐bound water molecule hydrogen bonded to the N atom of the accompanying free saccharinate anion.     

Crystal Structures of [Mn2(H2O)4(phen)2(C4H4O4)2] · 2 H2O and [Mn(phen)2(H2O)2][Mn(phen)2(C4H4O4)](C4H4O4) · 7 H2O

Reactions of 1,10‐phenanthroline monohydrate, Na₂C₄H₄O₄ · 6 H₂O and MnSO₄ · H₂O in CH₃OH/H₂O yielded a mixture of [Mn₂(H₂O)₄(phen)₂(C₄H₄O₄)₂] · 2 H₂O ( 1 ) and [Mn(phen)₂(H₂O)₂][Mn(phen)₂(C₄H₄O₄)](C₄H₄O₄) · 7 H₂O ( 2 ). The crystal structure of 1 (P1 (no. 2), a = 8.257(1) Å, b = 8.395(1) Å, c = 12.879(2) Å, α = 95.33(1)°, β = 104.56(1)°, γ = 106.76(1)°, V = 814.1(2) ų, Z = 1) consists of the dinuclear [Mn₂(H₂O)₄(phen)₂(C₄H₄O₄)₂] molecules and hydrogen bonded H₂O molecules. The centrosymmetric dinuclear molecules, in which the Mn atoms are octahedrally coordinated by two N atoms of one phen ligand and four O atoms from two H₂O molecules and two bis‐monodentate succinato ligands, are assembled via π‐π stacking interactions into 2 D supramolecular layers parallel to (101) (d(Mn–O) = 2.123–2.265 Å, d(Mn–N) = 2.307 Å). The crystal structure of 2 (P1 (no. 2), a = 14.289(2) Å, b = 15.182(2) Å, c = 15.913(2) Å, α = 67.108(7)°, β = 87.27(1)°, γ = 68.216(8)°, V = 2934.2(7) ų, Z = 2) is composed of the [Mn(phen)₂(H₂O)₂]²⁺ cations, [Mn(phen)₂(C₄H₄O₄)] complex molecules, (C₄H₄O₄)^2– anions, and H₂O molecules. The (C₄H₄O₄)^2– anions and H₂O molecules form 3 D hydrogen bonded network and the cations and complex molecules in the tunnels along [001] and [011], respectively, are assembled via the π‐π stacking interactions into 1 D supramolecular chains. The Mn atoms are octahedrally coordinated by four N atoms of two bidentate chelating phen ligands and two water O atoms or two carboxyl O atoms (d(Mn–O) = 2.088–2.129 Å, d(Mn–N) = 2.277–2.355 Å). Interestingly, the succinato ligands in the complex molecules assume gauche conformation bidentately to chelate the Mn atoms into seven‐membered rings.     

Bis(μ‐hexa­methyl­enetetr­amine)­bis(aqua­di­bromo­cadmium)­di­aqua­di­bromo­cadmium dihydrate

The title compound, poly­[[di­aqua­di­bromo­cadmium‐μ‐(1,3,5,7‐tetra­aza­tri­cyclo[3.3.1.1^3,7]decane‐N¹:N⁵)‐aqua­cad­mium‐di‐μ‐bromo‐aqua­cadmium‐μ‐(1,3,5,7‐tetra­aza­tri­cyclo[3.3.1.1^3,7]decane‐N¹:N⁵)‐di‐μ‐bromo] dihydrate], [Cd₃­Br₆­(C₆­H₁₂­N₄)₂­(H₂O)₄]·­2H₂O, is made up of two‐dimensional neutral rectangular coordination layers. Each rectangular subunit is enclosed by a pair of Cd₃(μ₂‐Br)₆(H₂O)₃ fragments and a pair of (μ₂‐hmt)Cd(H₂O)₂Br₂(μ₂‐hmt) fragments as sides (hmt is hexa­methyl­enetetr­amine). The unique Cd^II atom in the Cd₂Br₂ ring in the Cd₃(μ₂‐Br)₆(H₂O)₃ fragment is in a slightly distorted octahedral CdNOBr₄ geometry, surrounded by one hmt ligand [2.433 (5) Å], one aqua ligand [2.273 (4) Å] and four Br atoms [2.6409 (11)–3.0270 (14) Å]. The Cd^II atom in the (μ₂‐hmt)Cd(H₂O)₂Br₂(μ₂‐hmt) fragment lies on an inversion center and is in a highly distorted octahedral CdN₂O₂Br₂ geometry, surrounded by two trans‐related N atoms of two hmt ligands [2.479 (5) Å], two trans‐related aqua ligands [2.294 (4) Å] and two trans‐related Br atoms [2.6755 (12) Å]. Adjacent two‐dimensional coordination sheets are connected into a three‐dimensional network by hydrogen bonds involving lattice water mol­ecules, and the aqua, bromo and hmt ligands belonging to different layers.     

Tetra­aqua­bis(5‐carb­oxy‐2‐nitro­benzo­ato‐κO)manganese(II) dihydrate: a metal–water chain complex containing cyclic water tetra­mers

In the title complex, [Mn(C₈H₄NO₆)₂(H₂O)₄]·2H₂O, cyclic water tetra­mers forming one‐dimensional metal–water chains have been observed. The water clusters are trapped by the co‐­operative association of coordination inter­actions and hydrogen bonds. The Mn^II ion resides on a center of symmetry and is in an octa­hedral coordination environment comprising two O atoms from two 5‐carboxy‐2‐nitrobenzoate ligands and four O atoms from water mol­ecules.     

Bis(dimethyl sulfoxide‐S)tetrakis(μ‐p‐hydroxybenzoato‐O:O′)dirhodium(II)–tetrakis(μ‐butyrato‐O:O′)bis(dimethyl sulfoxide‐S)dirhodium(II) cocrystal ethanol disolvate

The title structure, [Rh₂(C₇H₅O₃)₄(C₂H₆OS)₂]·[Rh₂(C₄H₇­O₂)₄(C₂H₆OS)₂]·2C₂H₆O, contains two discrete neutral Rh–Rh dimers cocrystallized as the ethanol disolvate. Each dimer is situated on an inversion center. The butyrate chain displays disorder in one C‐atom position. In each dimer, the di­methyl sulfoxide ligand (dmso) is bound via S, as expected. The ethanol is a hydrogen‐bond acceptor for one p‐hydroxy­benzoate hydroxyl group and acts as a hydrogen‐bond donor to the dmso O atom of a neighboring p‐hydroxy­benzoate dirhodium complex. A third hydrogen bond is formed from the other p‐hydroxy­benzoate hydroxyl group to the dmso O atom of a butyrate–dirhodium complex.     

Hydro­gen‐bonded adducts of ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol): monomeric and polymeric adducts with 1,2‐bis(4‐pyridyl)­ethene and 1,6‐di­amino­hexane

In the adduct ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–1,2‐bis(4‐pyridyl)­ethene (1/1), [Fe(C₁₈H₁₅O)₂]·C₁₂H₁₀N₂, there is an intramolecular O—H?O hydrogen bond in the ferro­cene­diol component and a single O—H?N hydrogen bond linking the diol to the di­amine, which is disordered over two sets of sites, so forming a finite monomeric adduct. In the adduct ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–1,6‐di­amino­hexane (2/1), 2[Fe(C₁₈H₁₅O)₂]·C₆H₁₆N₂, the amine lies across a centre of inversion in space group P. There is an intramolecular O—H?O hydrogen bond in the ferrocenediol, and the molecular components are linked by O—H?N and N—H?O hydrogen bonds, one of each type, into a C(13)[R(12)] chain of rings.     

Bis[tris­(2,2′‐bipyridine)iron(II)] tetra­aqua­sodium(I) dodeca­tungsto­ferrate(III) dihydrate

The title compound, bis­[tris­(2,2′‐bipyridine)iron(II)] tetra­aqua­tetra‐μ₄‐oxo‐penta­cosa‐μ₂‐oxo‐undeca­oxo­iron(III)sodium(I)­dodeca­tungsten(VI) dihydrate, [Fe(C₁₀H₈N₂)₃]₂[NaFeW₁₂O₄₀(H₂O)₄]·2H₂O, consists of a dodeca­tungstoferrate(III) framework grafted on to an [Na(H₂O)₄]⁺ cation, two complex [Fe(2,2′‐bipy)₃]²⁺ cations (2,2′‐bipy is 2,2′‐bipyridine) and two uncoordinated water mol­ecules per formula unit.     

Three different bonding modes of cyano groups in the coordination polymer [Cu(en)2(H2O)][Cu(en)2Ni2Cu2(CN)10]·2H2O (en is 1,2‐diaminoethane)

Partial reduction of the Cu^II ions in the aqueous system Cu^II–en–[Ni(CN)₄]^2? (1/1/1) (en is 1,2‐di­amino­ethane) yields a novel heterobimetallic mixed‐valence compound, poly­[[aqua­bis(1,2‐di­amino­ethane)copper(II)] [hexa‐μ‐cyano‐tetra­cyano­bis(1,2‐di­amino­ethane)­tricopper(I,II)­dinickel(II)] dihydrate], [Cu(C₂H₈N₂)₂(H₂O)][Ni₂Cu₃(CN)₁₀(C₂H₈N₂)₂]·2H₂O or [Cu(en)₂(H₂O)][Cu(en)₂Ni₂Cu₂(CN)₁₀]·2H₂O. The structure is formed by a negatively charged two‐dimensional array of the cyano complex [Cu(en)₂Ni₂Cu₂(CN)₁₀]_n^2n?, [Cu(en)₂(H₂O)]²⁺ complex cations and water mol­ecules of crystallization. These last are involved in a complicated hydrogen‐bonding system. The cyano groups act as terminal, μ₂‐bridging or μ₃‐bridging ligands.