Uncoordinated Water Research Articles

2-Methyl-5-nitro-1H-benzimidazol-6-amine dihydrate

The title benzimidazole mol­ecule, C8H8N4O2·2H2O, is planar with a maximum deviation of 0.079 (2) Å (for one of the O atoms in the nitro group). It crystallized as a dihydrate and inter­molecular O—H⋯O and N—H⋯O hydrogen bonds link the uncoordinated water mol­ecules, and the nitro and amine groups, respectively. In the crystal, N—H⋯O, O—H⋯N, O—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules to form a three-dimensional network. A π–π contact between the benzene rings, [centroid–centroid distance = 3.588 (1) Å] may further stabilize the crystal structure.

Bis(N,N′-dimethylethylenediammonium) tris(oxalato-κ2O1,O2)cobaltate(II) dihydrate: an ion-pair complex

The CoII ion in the title complex, (C4H14N2)2[Co(C2O4)3]·2H2O, is coordinated by three oxalate ions, resulting in a distorted octa­hedral geometry. Two uncoordinated water mol­ecules are present in asymmetric unit. Inter­molecular N—H⋯O and O—H⋯O hydrogen bonds between the different entities stabilize the crystal structure.

Cyclo-Tetra-kis(μ-3-acetyl-4-methyl-1H-pyrazole-5-carboxyl-ato-κN,O:N,O)tetra-kis[aqua-copper(II)] tetra-deca-hydrate.

The title compound, [Cu4(C7H6N2O3)4(H2O)4]·14H2O, a tetra­nuclear [2 × 2] grid-type complex with S4 symmetry, contains four CuII atoms which are bridged by four pyrazole­carboxyl­ate ligand anions and are additionally bonded to a water molecule. Each CuII atom is coordinated by two O atoms of the carboxyl­ate and acetyl groups, two pyrazole N atoms of doubly deprotonated 3-acetyl-4-methyl-1H-pyrazole-5-carb­oxy­lic acid and one O atom of a water mol­ecule. The geometry at each CuII atom is distorted square-pyramidal, with the two N and two O atoms in the equatorial plane and O atoms in the axial positions. O—H⋯O hydrogen-bonding interactions additionally stabilize the structure. One of the uncoordinated water molecules shows half-occupancy.

The Structure of Water in p‐Sulfonatocalix[4]arene

Tetrasodium p-sulfonatocalix[4]arene exists as a hydrate with approximately 14 water molecules and has three polymorphic modifications, all of which contain a water molecule in the molecular cavity that is engaged in OH···π interactions. Single-crystal neutron structures are reported for two of these three forms and reveal a "compressed" water molecule with short OH bonds. Partial atomic charges and hardness analysis (PACHA) calculations based on the neutron coordinates give an OH···π interaction energy of 6.9-7.5 kJ mol(-1). The PACHA analysis also reveals the dominance of the charge-assisted hydrogen bonds from the Na(+)-coordinated water molecules. The instability of the crystal towards dehydration can be traced to an uncoordinated lattice water site. The remarkable calixarene-Na(+)-hydrate motif is conserved almost unchanged across all three polymorphs. A single-crystal neutron structure is also reported for pentasodium p-sulfonatocalix[4]arene·12H(2)O, which exhibits an intracavity water molecule that is engaged in both OH···π and OH···O hydrogen bonding. The shorter covalent bond to the hydrogen atom that forms the interaction with the aromatic ring is again apparent.

Poly[[aqua(μ7-biphenyl-3,3′,4,4′-tetracarboxylato)(1,10-phenanthroline)dicobalt(II)] monohydrate

In the title compound, {[Co2(C16H6O8)(C12H8N2)(H2O)2]·H2O}n, one CoII ion has a {CoN2O4} distorted octa­hedral environment defined by two N atoms of one 1,10-phenanthroline (phen) ligand, three O atoms of the carboxyl­ate groups of three biphenyl-3,3′,4,4′-tetra­carboxyl­ate (BPTC) ligands, one of which is bidentate, and one O atom from one coordinated water mol­ecule. The other CoII atom is surrounded by six O atoms from four different BPTC ligands and one coordinated water mol­ecule. Each BPTC ligand forms eight coordination bonds with seven CoII atoms, leading to a layer structure along the ac plane. Uncoordinated water mol­ecules occupy the space between the layers, and inter­act via inter­layer O—H⋯O hydrogen bonds along the b axis, generating a three-dimensional supra­molecular network.

Trans-Bis(acetato-κO)diaquabis(2-aminopyrazine-κN4)manganese(II) dihydrate

The MnII atom in the title compound, [Mn(CH3COO)2(C4H5N3)2(H2O)2]·2H2O, is situated on a center of inversion and shows an octa­hedral coordination polyhedron made up by four O atoms and two N atoms. The octa­hedron is somewhat tetra­gonally distorted owing to the longer Mn—N bond [2.323 (3) Å]. The mononuclear complex mol­ecule and uncoordinated water mol­ecules are linked by O—H⋯N, N—H⋯O and O—H⋯O hydrogen bonds, generating a three-dimensional network.

Poly[[tetra-aqua-bis-(μ(3)-1H-imidazole-4,5-dicarboxyl-ato)tetra-kis-(μ(2)-1H-imidazole-4,5-dicarboxyl-ato)tricobalt(II)diytterbium(III)] dihydrate

The asymmetric unit of the title compound, {[Co3Yb2(C5H2N2O4)6(H2O)4]·2H2O}n, contains one YbIII ion, two CoII ions (one situated on an inversion centre), three imidazole-4,5-dicarboxyl­ate ligands, two coordinated water mol­ecules and one uncoordinated water mol­ecule. The YbIII ion is seven-coordinated, in a monocapped trigonal prismatic coordination geometry, by six O atoms from three imidazole-4,5-dicarboxyl­ate ligands and one water O atom. Both CoII ions are six-coordinated in a slightly distorted octa­hedral geometry. The CoII ion that is located on an inversion center is coordinated by two O atoms from two water mol­ecules, as well as two O atoms and two N atoms from two imidazole-4,5-dicarboxyl­ate ligands. The second CoII ion is bonded to four O atoms and two N atoms from four imidazole-4,5-dicarboxyl­ate ligands. These metal coordination units are connected by bridging imidazole-4,5-dicarboxyl­ate ligands, generating a three-dimensional network. The crystal structure is further stabilized by N—H⋯O, O—H⋯O and C—H⋯O hydrogen-bonding inter­actions involving the water mol­ecules and the imidazole-4,5-dicarboxyl­ate ligands.

Poly[[μ-aqua-tetraaquabis(μ-2-hydroxy-4-oxocyclobut-1-ene-1,3-diolato)strontium] hemihydrate

In the title coordination polymer, {[Sr(C4HO4)2(H2O)5]·0.5H2O}n, the Sr2+ ion is coordinated by three monodentate hydrogensquarate (hsq) anions and six aqua ligands in a distorted SrO9 monocapped square-anti­prismatic geometry. The hsq anions and water mol­ecules bridge the metal ions into infinite sheets lying parallel to (100). The O atom of the uncoordinated water mol­ecule lies on a crystallographic twofold axis. The packing is stabilized by numerous O—H⋯O hydrogen bonds.

Catena-Poly[[(aqualithium)-μ-3-carboxypyrazine-2-carboxylato-κ4O2,N1:O3,N4] monohydrate

The polymeric structure of the title compound {[Li(C6H3N2O4)(H2O)]·H2O}n, contains two symmetry-independent LiI complex units, both having distorted trigonal–bipyramidal coordination environments. The LiI ions are bridged by both the N and O atoms of the ligands, generating two symmetry-independent polymeric chains propagating along the b-axis direction. In both ligands, the second carboxyl­ato O atom remains protonated, serving as a donor in a short intra­molecular O—H⋯O hydrogen bond. The coordination of each LiI ion is completed by a water O atom. The ribbons are held together by a network of O—H⋯O hydrogen bonds in which the coordinated and uncoordinated water mol­ecules are donors and the carboxyl­ato O atoms act as acceptors.

Triaqua(7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylato-κ3O2,O3,O7)cobalt(II) monohydrate

The title complex, [Co(C8H8O5)(H2O)3]·H2O, was synthesized by reaction of cobalt acetate with 7-oxabicyclo­[2.2.1]heptane-2,3-dicarb­oxy­lic anhydride (norcantharidin) in aqueous solution. In the mol­ecule, the CoII atom is six-coordinated in a distorted octa­hedral environment, binding to the bridging O atom of the bicyclo­heptane unit, to two O atoms from monodentate carboxyl­ate groups and to three water O atoms. The crystal structure is stabilized by several O—H⋯O hydrogen-bonding inter­actions involving both the coordinated and uncoordinated water mol­ecules as donors and the carboxyl­ate O atoms of neighbouring mol­ecules as acceptors.

Tetraaqua{1-[(1H-1,2,3-benzotriazol-1-yl)methyl]-1H-1,2,4-triazole}sulfatocobalt(II) dihydrate

In the title complex, [Co(SO4)(C9H8N6)(H2O)4]·2H2O, the CoII ion is six-coordinated by one N atom from a 1H-1,2,3-benzotriazol-1-yl)meth­yl]-1H-1,2,4-triazole ligand, one O atom from a monodentate sulfate ligand and four water mol­ecules in a slightly distorted octa­hedral geometry. The sulfate ligand is rotationally disordered over two sets of sites with refined occupancies of 0.662 (15) and 0.338 (15). In the crystal, complex mol­ecules and solvent water mol­ecules are linked through inter­molecular O—H⋯O and O—H⋯N hydrogen bonds into a three-dimensional network.

Aquachloridobis(2-{[3-(morpholin-4-yl)propyl]iminomethyl}phenolato)manganese(III) monohydrate

In the title compound, [Mn(C14H19N2O2)2Cl(H2O)]·H2O, the MnIII atom is N,O-chelated by two monoanionic Schiff bases, forming two six-membered chelate rings. One Cl atom and one water mol­ecule in trans positions complete a distorted octa­hedral geometry around the metal atom. In the crystal, the complex mol­ecules and the uncoordinated water mol­ecules are connected via O—H⋯N, O—H⋯O and O—H⋯Cl hydrogen bonds into layers parallel to the ac plane and these are consolidated by C—H⋯π inter­actions. The layers are further linked into a three-dimensional network through C—H⋯O inter­actions.

Chromium(III) complexes with 2-(2′-pyridyl)imidazole: Synthesis, crystal structure and magnetic properties

The preparation, crystal structure and variable temperature-magnetic investigation of three 2-(2′-pyridyl)imidazole-containing chromium(III) complexes of formula PPh4[Cr(pyim)(C2O4)2]·H2O (1), AsPh4[Cr(pyim)(C2O4)2]·H2O (2) and [Cr2(pyim)2(C2O4)2(OH2)2]·2pyim · 6H2O (3) [pyim=2-(2′-pyridyl)imidazole, C2O42-=dianion of oxalic acid, PPh4+=tetraphenylphosphonium cation and AsPh4+=tetraphenylarsonium cation] are reported herein. The isomorphous compounds are made up of discrete [Cr(pyim)(C2O4)2]− anions, XPh4+ cations [X=P (1) and As (2)] and uncoordinated water molecules. The chromium environment in 1 and 2 is distorted octahedral with Cr–N and Cr–O bond distances varying in the ranges 2.040(3)–2.101(3) and 1.941(3)–1.959(3)Å, respectively. The angle subtended by the chromium(III) ion by the two didentate oxalate ligands cover the range 82.49(12)–82.95(12)°, values which are somewhat greater than those concerning the chelating pyim molecule [77.94(13) (1) and 78.50(13)° (2)]. Complex 3 contains discrete centrosymmetric [Cr2(pyim)2(C2O4)2(OH)2] neutral units where the two chromium(III) ions are joined by a di-μ-hydroxo bridge, the oxalate and pyim groups acting as peripheral didentate ligands. Uncoordinated water and pyim molecules are also present in 3 and they contribute to the stabilization of its structure by extensive hydrogen bonding and π–π type interactions. The values of the intramolecular chromium–chromium separation and angle at the hydroxo bridge in 3 are 2.9908(12)Å and 99.60(16)°, respectively. Magnetic susceptibility measurements of 1–3 in the temperature range 1.9–300K show the occurrence of weak inter- (1 and 2) and intramolecular (3) antiferromagnetic couplings. The magnetic properties of 3 have been interpreted in terms of a temperature-dependent exchange integral, small changes of the angle at the hydroxo bridge upon cooling being most likely responsible for this peculiar magnetic behavior.

Poly[[diaqua-μ6-succinato-di-μ5-succinato-didysprosium(III)] monohydrate

The title compound, {[Dy2(C4H4O4)3(H2O)2]·H2O}n, is isostructural with other lanthanide succinates of the same formula. The DyIII atom is nine-coordinated in a tricapped trigonal–prismatic environment by eight O atoms, derived from six carboxyl­ate groups and a water mol­ecule. One of the independent succinate anions is located about a crystallographic inversion center and the uncoordinated water mol­ecule lies on a twofold axis. The crystal structure comprises edge-shared DyO9 polyhedra linked by succinate bridges, forming a three-dimensional network architecture. Intra- and inter­molecular O—H⋯O hydrogen bonds are present in the crystal structure.

(Naphthalene-2,3-diolato-κ2O,O′)[tris(2-pyridylmethyl)amine-κ4N]cobalt(III) hexafluoridophosphate hemihydrate

In the title complex, [Co(C10H6O2)(C18H18N4)]PF6·0.5H2O, the CoIII ion is six-coordinated in a distorted octa­hedral geometry by four N atoms from a tris­(2-pyridyl­meth­yl)amine ligand and two O atoms from a naphthalene-2,3-diolate ligand. The asymmetric unit contains two complex cations, two hexa­fluoridophosphate anions and one uncoordinated water mol­ecule. In one of the hexa­fluoridophosphate anions, four of the F aroms are disordered over two sets of sites in a 0.632 (11):0.368 (11) ratio. In the crystal, the cations, anions and water mol­ecules are connected by O—H⋯O and O—H⋯F hydrogen bonds. π–π inter­actions are present between the pyridine rings [centroid–centroid distance = 3.814 (1) Å].

Propane-1,2-diaminium bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6)cadmate dihydrate

The reaction of cadmium nitrate dihydrate, propane-1,2-diamine and pyridine-2,6-dicarb­oxy­lic acid in a 1:1:2 molar ratio in an aqueous solution resulted in the formation of the title compound, (C3H12N2)[Cd(C7H3NO4)2]·2H2O or (p-1,2-daH2)-[Cd(pydc)2]·2H2O (where p-1,2-da is propane-1,2-diamine and pydcH2 is pyridine-2,6-dicarb­oxy­lic acid). The CdII ion is coordinated by four O and two N atoms of two pydc ligands in a distorted octa­hedral environment. The structure also contains two uncoordinated water mol­ecules. In the crystal, there are several inter­molecular N—H⋯O, O—H⋯O and weak C—H⋯O hydrogen bonds. There are also π–π stacking inter­actions between the pyridine rings of pydc units, with centroid–centroid distances of 3.4708 (16) Å.

Propane-1,2-diaminium bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6)mercurate(II) dihydrate

In the title compound, (C3H12N2)[Hg(C7H3NO4)2]·2H2O, the HgII ion is coordinated by four O and two N atoms of two pyridine-2,6-dicarboxyl­ate (pydc) ligands in a distorted octa­hedral environment. The structure contains two uncoordinated water mol­ecules. In the crystal, N—H⋯O, O—H⋯O and weak C—H⋯O hydrogen bonds and π–π stacking inter­actions between the pyridine rings of the pydc ligands, with a centroid–centroid distance of 3.4582 (18) Å, stabilize the structure.

μ-1,4-Bis(1,2,4-triazol-1-ylmethyl)benzene]bis[aqua(pyridine-2,6-dicarboxylato)copper(II)] monohydrate

The title compound, [Cu2(C7H3NO4)2(C12H12N6)(H2O)2]·H2O, displays a discrete dinuclear structure, in which the central CuII atom is five-coordinated in a distorted square-based pyramidal coordination geometry and the flexible ligand 1,4-bis­(1,2,4-triazol-1-ylmeth­yl)benzene adopts a bis-monodentate bridging mode linking the CuII atoms. It is further assembled by O—H⋯O hydrogen-bond inter­actions involving both the coordinated and uncoordinated water molecules. The latter exhibits half-occupancy.

Poly[hemi(hexaaquazinc) [[μ2-1,3-bis(1,2,4-triazol-1-yl)methane](μ2-5-sulfonatobenzene-1,3-dicarboxylato)zinc] sesquihydrate

The title coordination polymer, {[Zn(H2O)6]0.5[Zn(C8H3O7S)(C5H6N6)]·1.5H2O}n, synthesized under hydro­thermal conditions, possesses a one-dimensional tube-like chain structure along [100], with octahedral [Zn(H2O)6]2+ groups ( symmetry) trapped in the pores. The other Zn atom is five-coordinated in a highly distorted trigonal–biyramidal coordin­ation that is defined by two different N atoms from two 1,3-bis­(1,2,4-triazol-1-yl)methane (btrm) ligands and three carboxyl­ate O atoms from 5-sulfonato­benzene-1,3-dicarboxyl­ate ligands. The chains carry negative charges, whereas the free [Zn(H2O)6]2+ cations are positively charged. The [Zn(H2O)6]2+ cation is connected with the one-dimensional tubelike chain through weak classical O—H⋯O and O—H⋯N hydrogen-bonding inter­actions as well as through electrostatic inter­actions. One of the two uncoordinated water molecules exhibits half-occupancy.

Catena-Poly[[[aquabis(4,4′-bipyridine-κN)zinc]-μ-L-tyrosinato-κ3N,O1:O1′] nitrate dihydrate

In the title compound, {[Zn(C9H10NO3)(C10H8N2)2(H2O)]NO3·2H2O}n, the ZnII atom is six-coordinated in a distorted octa­hedral geometry by two carboxyl­ate O atoms and one amino N atom from two l-tyrosinate ligands, two N atoms from two 4,4′-bipyridine ligands, and one water mol­ecule. Adjacent Zn atoms are bridged by the bidentate carboxyl­ate groups into a cationic chain extending along [010]. N—H⋯N, O—H⋯N and O—H⋯O hydrogen bonds link the cationic chains, nitrate anions and uncoordinated water mol­ecules into a supra­molecular network. π–π inter­actions between the pyridine rings and between the pyridine and benzene rings [centroid–centroid distances = 3.615 (4) and 3.636 (4) Å] are present.