ALBERT

Beschreibung: Single crystals of the high-temperature form I of [Co(NCS)2(DMAP)2] (DMAP = 4-dimethylaminopyridine, C7H10N2) were obtained accidentally by the reaction of Co(NCS)2 with DMAP at slightly elevated temperatures under kinetic control. This modification crystallizes in the monoclinic space group P21/m and is isotypic with the corresponding Zn compound. The asymmetric unit consists of one crystallographically independent Co cation and two crystallographically independent thiocyanate anions that are located on a crystallographic mirror plane and one DMAP ligand (general position). In its crystal structure the discrete complexes are linked by C—H...S hydrogen bonds into a three-dimensional network. For comparison, the crystal structure of the known low-temperature form II, which is already thermodynamically stable at room temperature, was redetermined at the same temperature. In this polymorph the complexes are connected by C—H...S and C—H...N hydrogen bonds into a three-dimensional network. At 100 K the density of the high-temperature form I (ρ = 1.462 g cm−3) is lower than that of the low-temperature form II (ρ = 1.457 g cm−3), which is in contrast to the values determined by XRPD at room temperature. Therefore, these two forms represent an exception to the Kitaigorodskii density rule, for which extensive intermolecular hydrogen bonding in form II might be responsible.

Beschreibung: A dinuclear nickel complex with (S)-limonene based aminooxime ligand has been isolated and its crystal structure determined. The resolved structure of dichloridobis{(2S,5R)-2-methyl-5-(prop-1-en-2-yl)-2-[(pyridin-2-yl)methylamino]cyclohexan-1-one oxime}dinickel(II), [Ni2Cl2(C16H23ClN3O)2], at 100 K has monoclinic (P21) symmetry. The two NiII ions in the dinuclear complex are each coordinated in a distorted octahedral environment by three nitrogen atoms, a terminal chloride and two μ bridging chlorides. Each oxime ligand is coordinated to nickel(II) by the three nitrogen atoms, leading to two five-membered chelate rings, each displaying an envelope conformation. In the crystal, numerous intermolecular and intramolecular hydrogen bonds lead to the formation of a three-dimensional network structure.

Beschreibung: A hydrogen sulfate salt, C15H18NSe+·HSO4 −·H2O or [BnSeCH2CH(Ph)NH3 +](HSO4 −), of a chiral selenated amine (R)-2-(benzylselanyl)-1-phenylethanamine (BnSeCH2CH(Ph)NH2) has been synthesized and characterized by elemental analysis,1H and 13C{1H} NMR, FT–IR analysis, and single-crystal X-ray diffraction studies. The title salt crystallizes in the monohydrate form in the non-centrosymmetric monoclinic P21 space group. The cation is somewhat W shaped with the dihedral angle between the two aromatic rings being 60.9 (4)°. The carbon atom attached to the amine nitrogen atom is chiral and in the R configuration, and, the –C—C– bond of the –CH2—CH– fragment has a staggered conformation. In the crystal structure, two HSO4 − anions and two water molecules form an R 4 4(12) tetrameric type of assembly comprised of alternating HSO4 − anions and water molecules via discrete D(2) O—H...O hydrogen bonds. This tetrameric assembly aggregates along the b-axis direction as an infinite one-dimensional tape. Adjacent tapes are interconnected via discrete D(2) N—H...O hydrogen bonds between the three amino hydrogen atoms of the cation sandwiched between the two tapes and the three HSO4 − anions of the nearest asymmetric units, resulting in a complex two-dimensional sheet along the ab plane. The pendant arrangement of the cations is stabilized by C—H...π interactions between adjacent cations running as chains down the [010] axis. Secondary Se...O [3.1474 (4) Å] interactions are also observed in the crystal structure. A Hirshfeld surface analysis, including d norm, shape-index and fingerprint plots of the cation, anion and solvent molecule, was carried out to confirm the presence of various interactions in the crystal structure.

Beschreibung: The title compound, C9H7NO3, crystallizes in the monoclinic (P21) space group. In the crystal, the almost planar molecules display a flattened herringbone arrangement. Stacking molecules are slipped in the lengthwise and widthwise directions and are linked by π–π interactions [d(Cg...Cg = 3.6640 (11) Å]. The structure is characterized by strong C—H...N and weak C—H...O hydrogen bonds, and further stabilized by C–O...π interactions.

Beschreibung: In the cation of the title salt, C30H28NO2 +·CF3O3S−, the four tetrahydrofuran rings adopt envelope conformations. In the crystal, pairs of cations are linked by dimeric C—H...O hydrogen bonds, forming two R 2 2(6) ring motifs parallel to the (001) plane. The cations and anions are connected by further C—H...O hydrogen bonds, forming a three-dimensional network structure. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (47.6%), C...H/H...C (20.6%), O...H/H...O (18.0%) and F...H/H...F (9.9%) interactions.

Beschreibung: The crystal structure of the title solvated coordination compound, [Co(NCS)2(C6H12N4)2(H2O)2]·2C6H12N4·2C2H3N, consists of discrete complexes in which the Co2+ cations (site symmetry overline{1}) are sixfold coordinated by two N-bonded thiocyanate anions, two water molecules and two hexamethylenetetramine (HMT) molecules to generate distorted trans-CoN4O2 octahedra. The discrete complexes are each connected by two HMT solvate molecules into chains via strong O—H...N hydrogen bonds. These chains are further linked by additional O—H...N and C—H...N and C—H...S hydrogen bonds into a three-dimensional network. Within this network, channels are formed that propagate along the c-axis direction and in which additional acetonitrile solvent molecules are embedded, which are hydrogen bonded to the network. The CN stretching vibration of the thiocyanate ion occurs at 2062 cm−1, which is in agreement with the presence of N-bonded anionic ligands. XRPD investigations prove the formation of the title compound as the major phase accompanied by a small amount of a second unknown phase.

Beschreibung: In the title compound, C14H7Cl4FN2, the dihedral angle between the 4-fluorophenyl ring and the 2,4-dichlorophenyl ring is 46.03 (19)°. In the crystal, the molecules are linked by C—H...N interactions along the a-axis direction, forming a C(6) chain. The molecules are further connected by C—Cl...π interactions and face-to-face π–π stacking interactions, forming ribbons along the a-axis direction. Hirshfeld surface analysis indicates that the greatest contributions to the crystal packing are from Cl...H/H...Cl (35.1%), H...H (10.6%), C...C (9.7%), Cl...Cl (9.4%) and C...H/H...C (9.2%) interactions.

Beschreibung: The structures of the six hydrogen-bonded 1:1 compounds of 4-methylquinoline (C10H9N) with chloro- and nitro-substituted benzoic acids (C7H4ClNO4), namely, 4-methylquinolinium 2-chloro-4-nitrobenzoate, C10H10N+·C7H3ClNO4 −, (I), 4-methylquinoline–2-chloro-5-nitrobenzoic acid (1/1), C10H9N·C7H4ClNO4, (II), 4-methylquinolinium 2-chloro-6-nitrobenzoate, C10H9.63N0.63+·C7H3.37ClNO4 0.63−, (III), 4-methylquinolinium 3-chloro-2-nitrobenzoate, C10H9.54N0.54+·C7H3.46ClNO4 0.54−, (IV), 4-methylquinolinium 4-chloro-2-nitrobenzoate, C10H10N+·C7H3ClNO4 −, (V), and 4-methylquinolinium 5-chloro-2-nitrobenzoate, C10H10N+·C7H3ClNO4 −, have been determined at 185–190 K. In each compound, the acid and base molecules are linked by a short hydrogen bond between a carboxy (or carboxylate) O atom and an N atom of the base. The O...N distances are 2.5652 (14), 2.556 (3), 2.5485 (13), 2.5364 (13), 2.5568 (13) and 2.5252 (11) Å, respectively, for compounds (I)–(VI). In the hydrogen-bonded acid–base units of (III) and (IV), the H atoms are each disordered over two positions with O site:N site occupancies of 0.37 (3):0.63 (3) and 0.46 (3):0.54 (4), respectively, for (III) and (IV). The H atoms in the hydrogen-bonded units of (I), (V) and (VI) are located at the N-atom site, while the H atom in (II) is located at the O-atom site. In all the crystals of (I)–(VI), π–π stacking interactions between the quinoline ring systems and C—H...O hydrogen bonds are observed. Similar layer structures are constructed in (IV)–(VI) through these interactions together with π–π interactions between the benzene rings of the adjacent acid molecules. A short Cl...Cl contact and an N—O...π interaction are present in (I), while a C—H...Cl hydrogen bond and a π–π interaction between the benzene ring of the acid molecule and the quinoline ring system in (II), and a C—H...π interaction in (III) are observed. Hirshfeld surfaces for the title compounds mapped over d norm and shape index were generated to visualize the weak intermolecular interactions.

Beschreibung: In the fused ring system of the title compound, C24H27BrO5, the mean plane and maximum deviations of the central pyran ring are 0.0384 (2) and 0.0733 (2) Å, respectively. The cyclohexenone rings both adopt envelope conformations with the tetra-substituted C atoms as flap atoms, whereas the central pyran ring adopts a flattened boat conformation. The central pyran and phenyl substituent rings are almost perpendicular to each other, making a dihedral angle of 89.71 (2)°. In the crystal, pairs of molecules are linked via O—H...O hydrogen bonds, forming inversion dimers with an R 2 2(20) ring motif. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H...H (50.6%), O...H/H...O (22.9%) and C...H/H...C (11.1%) contacts. Quantum chemical calculations for the frontier molecular orbitals were undertaken to determine the chemical reactivity of the title compound.

Beschreibung: As part of our ongoing investigation on the chemical and biological properties of piperazinium salts, we synthesized three novel compounds: 1-ethylpiperazinium 3,5-dinitrobenzoate (I), 1-methylpiperazinium 3,5-dinitrobenzoate (II) and 1-methylpiperazinium 4-iodobenzoate (III). The crystal structures of these compounds are built up of organic layers formed by the strong connection between the molecules by hydrogen bonds of type N—H...O. These layers are linked through N—H...O hydrogen bonds and C—H...O interactions or C—I...N halogen bonding, leading to the formation of a three-dimensional network.

Beschreibung: The title compound, C21H25NO3, crystallized as a racemic twin in the Sohnke space group P21. In the molecular structure of the title compound, both enantiomers show a highly similar conformation with the urethane function and the benzoyl group showing an almost perpendicular arrangement [the dihedral angle is 72.46 (8)° in the S-enantiomer and 76.21 (8)° in the R-enantiomer]. In the crystal structure, molecules of both enantiomers show infinite helical arrangements parallel to the b axis formed by weak C—H...O hydrogen bonds between the phenyl ring of the benzoyl group and the carbamate carbonyl group. In case of the R-enantiomer, this helix is additionally stabilized by a bifurcated hydrogen bond between the carbonyl function of the benzoyl group towards both phenyl groups of the molecule.

Beschreibung: The structure of the title salt, ammonium carbamoylcyanonitrosomethanide, NH4 +·C3H2N3O2 −, features the co-existence of different hydrogen-bonding patterns, which are specific to each of the three functional groups (nitroso, carbamoyl and cyano) of the methanide anion. The nitroso O-atoms accept as many as three N—H...O bonds from the ammonium cations [N...O = 2.688 (3)–3.000 (3) Å] to form chains of fused rhombs [(NH4)(O)2]. The most prominent bonds of the carbamoyl groups are mutual and they yield 21 helices [N...O = 2.903 (2) Å], whereas the cyano N-atoms accept hydrogen bonds from sterically less accessible carbamoyl H-atoms [N...N = 3.004 (3) Å]. Two weaker NH4 +...O=C bonds [N...O = 3.021 (2), 3.017 (2) Å] complete the hydrogen-bonded environment of the carbamoyl groups. A Hirshfeld surface analysis indicates that the most important interactions are overwhelmingly O...H/H...O and N...H/H...N, in total accounting for 64.1% of the contacts for the individual anions. The relatively simple scheme of these interactions allows the delineation of the supramolecular synthons, which may be applicable to crystal engineering of hydrogen-bonded solids containing polyfunctional methanide anions.

Beschreibung: In the structures of the title salts, poly[[μ4-4-(3,5-dinitropyrazol-4-yl)-3,5-dinitropyrazol-1-ido]rubidium], [Rb(C6HN8O8)] n , (1), and its isostructural caesium analogue [Cs(C6HN8O8) n , (2), two independent cations M1 and M2 (M = Rb, Cs) are situated on a crystallographic twofold axis and on a center of inversion, respectively. Mutual intermolecular hydrogen bonding between the conjugate 3,5-dinitopyrazole NH-donor and 3,5-dinitropyrazole N-acceptor sites of the anions [N...N = 2.785 (2) Å for (1) and 2.832 (3) Å for (2)] governs the self-assembly of the translation-related anions in a predictable fashion. Such one-component modular construction of the organic subtopology supports the utility of the crystal-engineering approach towards designing the structures of polynitro energetic materials. The anionic chains are further linked by multiple ion–dipole interactions involving the 12-coordinate cations bonded to two pyrazole N-atoms [Rb—N = 3.1285 (16), 3.2261 (16) Å; Cs—N = 3.369 (2), 3.401 (2) Å] and all of the eight nitro O-atoms [Rb—O = 2.8543 (15)–3.6985 (16) Å; Cs—O = 3.071 (2)–3.811 (2) Å]. The resulting ionic networks follow the CsCl topological archetype, with either metal or organic ions residing in an environment of eight counter-ions. Weak lone pair–π-hole interactions [pyrazole-N atoms to NO2 groups; N...N = 2.990 (3)–3.198 (3) Å] are also relevant to the packing. The Hirshfeld surfaces and percentage two-dimensional fingerprint plots for (1) and (2) are described.

Beschreibung: The structure of ethyl 1-[N-(4-methylphenyl)-N-(methylsulfonyl)alanyl]piperidine-4-carboxylate, C19H28N2O5S, I, a compound of interest as activator of Ubiquitin C-terminal Hydrolase-L1 (UCH-L1), was determined by single-crystal X-ray diffraction (SCXRD) analysis. In order to find new activators, a derivative of compound I, namely, 1-[N-(4-methylphenyl)-N-(methylsulfonyl)alanyl]piperidine-4-carboxylic acid, C17H24N2O5S, II, was studied. The synthesis and crystal structure are also reported. Despite being analogues, different crystal packings are observed. Compound II bears a carboxylic group, which favors a strong hydrogen bond. A polymorph risk assessment was carried out to study interactions in compound II.

Beschreibung: The title compound, C17H7F8N3O, was obtained via the reaction of 1-azido-2,3,4,5,6-pentafluorobenzene with 4,4,4-trifluoro-1-(p-tolyl)butane-1,3-dione using triethylamine as a base catalyst and solvent. The dihedral angles between the pentafluorophenyl (A), triazole (B) and p-tolyl (C) rings are A/B = 62.3 (2), B/C = 43.9 (3) and A/C = 19.1 (3)°. In the crystal, the molecules are linked by C—H...F and C—H...O hydrogen bonds as well as by aromatic π–π stacking interactions into a three-dimensional network. To further analyse the intermolecular interactions, a Hirshfeld surface analysis was performed.

Beschreibung: The title compound, [Cu2Cl4(C5H10N2O2)2(CH3CN)2] or [Cu2(μ2-Cl)2(CH3—Pz-COOCH2CH3)2Cl2(CH3CN)2], was synthesized using a one-pot reaction of copper powder, copper(II) chloride dihydrate and ethyl 5-methyl-1H-pyrazole-3-carboxylate (CH3—Pz-COOCH2CH3) in acetonitrile under ambient conditions. This complex consists of discrete binuclear molecules with a {Cu2(μ2-Cl)2} core, in which the Cu...Cu distance is 3.8002 (7) Å. The pyrazole-based ligands are bidentate coordinated, leading to the formation of two five-membered chelate rings. The coordination geometry of both copper atoms (ON2Cl3) can be described as distorted octahedral on account of the acetonitrile coordination. A Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from H...H (40%), H...Cl/Cl...H (24.3%), H...O/O...H (11.8%), H...C/C...H (9.2%) and H...N/N...H (8.3%) interactions.

Beschreibung: The title CoIII complex, bis[bis(2-hydroxy-3-methoxybenzaldehyde thiosemicarbazonato)cobalt(III)] dithionate–dimethylformamide–methanol (1/4/3), [Co(C9H10N3O2S)2]2(S2O6)·4C3H7NO·3CH3OH, with monodeprotonated 2-hydroxy-3-methoxybenzaldehyde thiosemicarbazone as ligands crystallizes in the space group Poverline{1}. The asymmetric unit consists of two mononuclear [CoL 2]+ cations, one dithionate anion (S2O6)2− as counter-anion and seven solvate molecules (four dimethylmethanamide and three methanol). Each CoIII ion has a moderately distorted octahedral S2N2O2 geometry. In the crystal, the components are linked by numerous N—H...O and O—H...O contacts.

Beschreibung: The reaction of dichlorodimethylsilane with a polydentate Schiff base ligand derived from pyridoxal and 2-ethanolamine yielded the macrocyclic silicon compound (8E,22E)-4,4,12,18,18,26-hexamethyl-3,5,17,19-tetraoxa-8,13,22,27-tetraaza-4,18-disilatricyclo[22.4.0.010,15]octacosa-1(24),8,10,12,14,22,25,27-octaene-11,25-diol, C24H36N4O6Si2. The asymmetric unit contains the half macrocycle with an intramolecular O—H...N hydrogen bond between the imine nitrogen atom and a neighbouring oxygen atom. The crystal structure is dominated by C—H...O and C—H...π interactions, which form a high ordered molecular network.

Beschreibung: The title compound, C16H17NO, is a Schiff base that exists in the enol–imine tautomeric form and adopts a Z configuration. The molecule is non-planar, with the twisted rings making a dihedral angle of 39.92 (4)°. The intramolecular O—H...N hydrogen bond forms an S(6) ring motif. In the crystal, molecules are linked by C—H...π interactions and very weak π-π stacking interactions also help to consolidate the crystal packing. A Hirshfeld surface analysis was performed to investigate the contributions of different intermolecular contacts within the supramolecular structure. The major contributions are from H...H (65%), C...H (19.2%) and O...H (6.6%) interactions.

Beschreibung: The title compound, [Cu2(C7H4NO4)4(C3H7NO)2]·(C3H7NO)2, is a binuclear copper(II) complex located on an inversion center midway between the two copper(II) cations. The asymmetric unit consists of one CuII cation, two 3-nitrobenzoato ligands, and two dimethylformamide (DMF) molecules, one of which coordinates to the CuII cation and one is a solvate molecule. The carboxylate groups of the ligands bridge two CuII cations with a Cu—Cu distance of 2.6554 (6) Å, completing a distorted octahedral O5Cu coordination environment. The dihedral angles between the carboxylate and the aromatic ring planes of the two independent ligands are different from one another, viz. 5.2 (3) and 23.9 (3)°. The three-dimensional structure is consolidated by weak C—H...O interactions and stabilized by π–π stacking interactions between the aromatic rings. The complex and the free ligand were further characterized by Fourier-transform infrared spectroscopy (FT–IR), and the energies of the frontier molecular orbitals of the complex were determined by DFT calculations at the B3LYP/def2-TZVP level of theory.

Beschreibung: The asymmetric unit of the title compound, catena-poly[[[(1,4,8,11-tetraazacyclotetradecane-κ4 N 1,N 4,N 8,N 11)nickel(II)]-μ-cyanido-κ2 N:C-[bis(cyanido-κC)nickel(II)]-μ-cyanido-κ2 C:N] dihydrate], {[Ni2(CN)4(C10H24N4)]·2H2O] n or [{[Ni(C10H24N4)][Ni(CN)4]}·2H2O] n , consists of a pair of crystallographically non-equivalent macrocyclic cations and anions. The nickel(II) ions (all with site symmetry overline{1}) are coordinated by the four secondary N atoms of the macrocyclic ligands, which adopt the most energetically stable trans-III conformation, and the mutually trans N atoms of the tetracyanonickelate anion in a slightly tetragonally distorted NiN6 octahedral coordination geometry. The [Ni(CN)4)]2– anion exhibits a bridging function, resulting in the formation of parallel polymeric chains running along the [1overline{1}0] direction. The water molecules of crystallization play a pivotal role in the three-dimensional supramolecular organization of the crystal. Acting as acceptors, they form N—H...Ow (w = water) hydrogen bonds with the secondary amino groups of the macrocycles, forming layers oriented parallel to the (001) plane. At the same time, as donors, they interact with the non-coordinated cyano groups of the anion via Ow—H...Nc (c = cyanide) hydrogen bonds, giving two-dimensional layers oriented parallel to the (100) plane and thus generating a three-dimensional network.

Beschreibung: The title four-coordinate mononuclear complex, [Hg(C3H5OS2)2(C6H16N2)] or [Hg(C3H5OS2)2(tmeda)] (tmeda: N,N,N′,N′-tetramethylethane-1,2-diamine), has a distorted tetrahedral geometry. The HgII ion is coordinated to two N atoms of the N,N,N′,N′-tetramethylethylenediamine ligand and two S atoms from two ethylxanthate xanthate ligands. In the crystal, molecules are linked by weak C—H...S hydrogen bonds, forming a two-dimensional supramolecular architecture in the ab plane. The most important contributions for the crystal packing are from H...H (59.3%), S...H (27.4%) and O...H (7.5%) interactions.

Beschreibung: The title compounds, di-μ-chlorido-bis({2-[(η-2,3)-(prop-2-en-1-yl)sulfanyl]pyridine-κN}copper(I)), [Cu2Cl2(C8H9NS)2], and di-μ-bromido-bis({2-[(η-2,3)-(prop-2-en-1-yl)sulfanyl]pyridine-κN}copper(I)), [Cu2Br2(C8H9NS)2], were obtained by alternating-current electrochemical synthesis starting from an ethanolic solution of 2-[(prop-2-en-1-yl)sulfanyl]pyridine (Psup) and the copper(II) halide. The isostructural crystals are built up from centrosymmetric [Cu2 Hal 2(Psup)2] dimers, which are formed due to the π,σ-chelating behavior of the organic ligand. In the crystals, the dimers are linked by C—H...Hal hydrogen bonds as well as by aromatic π–π stacking interactions into a three-dimensional network.

Beschreibung: The asymmetric unit of the first title compound iodido(1,4,8,11-tetraazacyclotetradecane-κ4 N 1,N 4,N 8,N 11)zinc(II) iodide, [ZnI(C10H24N4)]I, I, consists of the zinc–cyclam macrocyclic cation with one iodide anion coordinated to the metal ion [Zn—I = 2.6619 (5) Å] and the second present as a counter-ion. The asymmetric unit of the second title compound iodido(1,4,8,11-tetraazacyclotetradecane-κ4 N 1,N 4,N 8,N 11)zinc(II) triiodide, [ZnI(C10H24N4)]I3, II, consists of half of the centrosymmetric macrocyclic cation, in which the ZnII ion coordinated to an iodide anion [Zn—I = 2.766 (2) Å] is disordered over two positions [Zn...Zn = 0.810 (3) Å], and of the two halves of the crystallographically non-equivalent, non-coordinated, centrosymmetric triiodide anions. In both compounds, the N,N,N,N-tetradentate macrocyclic ligand is present in the most energetically favored trans-III conformation. In the crystals of I, the [Zn(C10H24N4)I]+ cations and the non-coordinated iodide anions are linked by N—H...I and bifurcated N—H...(I,I) hydrogen bonds, resulting in the formation of two-dimensional networks lying parallel to the (001) and (101) planes. In contrast, the crystals of II are built up from infinite chains of the five-coordinate macrocyclic units arranged along the b-axis direction and perpendicular sheets formed of the triiodide counter-ions without significant hydrogen bonding between them.

Beschreibung: The asymmetric unit of the title compound, trans-diaqua(1,4,8,11-tetraazaundecane-κ4 N 1,N 4,N 8,N 11)nickel(II) bis(pyridine-2,6-dicarboxylato-κ3 O 2,N,O 6)nickel(II) {[Ni(L)(H2O)2][Ni(pdc)2] where L = 1,4,8,11-tetraazaundecane (C7H20N4) and pdc = the dianion of pyridine-2,6-dicarboxylic acid (C7H3NO4 2−)} consists of an [Ni(L)(H2O)2]2+ complex cation and a [Ni(pdc)2]2– anion. The metal ion in the cation is coordinated by the four N atoms of the tetraamine ligand and the mutually trans O atoms of the water molecules in a tetragonally elongated octahedral geometry with the average equatorial Ni—N bond length slightly shorter than the average axial Ni—O bond [2.087 (4) versus 2.128 (4) Å]. The ligand L adopts its energetically favored conformation with five-membered and six-membered chelate rings in gauche and chair conformations, respectively. In the complex anion, the NiII ion is coordinated by the two tridentate pdc2– ligands via their carboxylate and nitrogen atom donors in a distorted octahedral trans-NiO4N2 geometry with nearly orthogonal orientation of the planes defining the carboxylate rings and the average Ni—N bond length [1.965 (4) Å] shorter than the average Ni—O bond distance [2.113 (7) Å]. In the crystal, the NH donor groups of the tetraamine, the carboxylic groups of the pdc2– anion and the coordinated water molecules are involved in numerous N—H...O and O—H...O hydrogen bonds, leading to electroneutral sheets oriented parallel to the (001) plane.