Monoclinic modification of bis­(μ2-pyridine-2,6-dicarboxyl­ato)-κ4 O 2,N,O 6:O 6;κ4 O 2:O 2,N,O 6-bis­[aqua­dibutyl­tin(IV)]

The SnIV atom in the centrosymmetric dinuclear title compound, [Sn2(C4H9)4(C7H3NO4)2(H2O)2], exists in a trans-C2SnNO4 penta­gonal–bipyramidal geometry. There are two half-mol­ecules in the asymmetric unit that are completed by inversion symmetry. The crystal studied was a non-merohedral twin with a ratio of 47.3 (1)% for the minor twin component. Bond dimensions are similar to those found in the tetra­gonal polymorph [Huber et al. (1989 ▶). Acta Cryst. C45, 51–54]. O—H⋯O hydrogen-bonding interactions stabilize the crystal packing

(E)-2,4-Dihydroxy­benzaldehyde 4-ethyl­thio­semicarbazone–4,4′-bipyridine–water (4/7/2)

The asymmetric unit of the title compound, 7C10H8N2·4C10H13N3O2S·2H2O, contains two independent 2,4-hydroxy­benzaldehyde 4-ethyl­thio­semicarbazone mol­ecules, three and a half 4,4′-bipyridine mol­ecules and one water mol­ecule. Two of the 4,4′-bipyridine mol­ecules lie on general positions and the other three on centers of inversion. The two 4,4′-bipyridine mol­ecules on general positions and one of the three on special positions are disordered over two positions each with an occupancy of 0.50. The –NH—C(=S)—NH—NC fragment is close to planar in the two 2,4-hydroxy­benzaldehyde 4-ethyl­thio­semicarbazone mol­ecules (r.m.s. deviations = 0.04 and 0.05 Å). In the crystal, the Schiff base, N-heterocycle and water mol­ecules engage in O—H⋯O, O—H⋯N and N—H⋯O hydrogen-bonding inter­actions, generating a layer structure

A triclinic modification of 3,4-dihy­droxy­benzoic acid monohydrate

The unit cell of the title compound, C7H6O4·H2O, features four independent formula units; the individual carb­oxy­lic acid mol­ecules themselves are nearly planar (r.m.s. deviations = 0.0189, 0.0334, 0.0356 and 0.0441 Å). Two independent mol­ecules each form two hydrogen bonds by acid–carbonyl O—H⋯O inter­actions and the dimers are also nearly planar (r.m.s. deviations = 0.039 and 0.049 Å). The two independent dimers are aligned at 44.5 (1)°. Other O—H⋯O inter­actions involving the hy­droxy groups and water mol­ecules give rise to a three-dimensional network

1-(4-{[(E)-4-Methyl­benzyl­idene]amino}­phen­yl)ethanone oxime

In the title compound, C16H16N2O, the dihedral angle formed by the two benzene rings is 50.3 (1)°. In the crystal structure, mol­ecules are linked into an infinite one-dimensional supra­molecular structure by inter­molecular O—H⋯N hydrogen-bond inter­actions

(3-Amino­pyrazin-4-ium-2-carboxyl­ate-κ2 N 1,O)diaqua­zinc(II) dinitrate

The water-coordinated ZnII atom in the title salt, [Zn(C5H5N3O2)2(H2O)2](NO3)2, is N,O-chelated by a zwitterionic amino­pyraziniocarboxyl­ate unit; the metal atom, which lies on a center of inversion, shows an octa­hedral coordination. The nitrate ion inter­acts indirectly, through N—H⋯O hydrogen bonds. In the crystal, adjacent cations and anions are connected by O—H⋯O hydrogen bonds into a three-dimensional network motif. The crystal studied was a non-merohedral twin with two minor components of 15.1 (1) and 8.0 (1)%

A second monoclinic modification of phenyl quinoxalin-2-yl ether

The two aromatic systems in the title compound, C14H10N2O, enclose a dihedral angle of 77.9 (1)°, and the C—O—C inter-ring bond angle is 117.6 (1)°

trans-Bis(acetato-κO)diaquabis­(2-amino­pyrazine-κN 4)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

catena-Poly[[[dichloridomercury(II)]-μ-1,4-bis­(3-pyridyl­amino­meth­yl)benzene-κ2 N:N′] N,N-dimethyl­formamide monosolvate]

The crystal structure of the polymeric title compound, {[HgCl2(C18H18N4)]·C3H7NO}n, features an N-heterocyclic ligand which links adjacent HgCl2 units into a helical chain running along the b axis. The coordination geometry of the HgII atom is a distorted tetra­hedron. The dimethyl­formamide mol­ecule is disordered over two positions in a 1:1 ratio, and is linked to the complex mol­ecules via N—H⋯O hydrogen bonds

(μ-Naphthalene-1,5-disulfonato-κ2 O 1:O 5)bis­[triaqua­(glycinato-κ2 N,O)copper(II)]

In the title compound, [Cu2(C2H4NO2)2(C10H6O6S2)(H2O)6], the naphthalene­disulfonate group lies on a center of inversion and bridges two glycinate-chelated CuII atoms. The CuII atom exists in a CuNO4 square-pyramidal geometry that is distorted towards an octa­hedron owing to a long Cu—Osulfonate bond [2.636 (2) Å]. In the crystal, extensive N—H⋯O and O—H⋯O hydrogen bonds link adjacent mol­ecules into a three-dimensional networ

Poly[[(μ-3-amino­pyrazine-2-carboxyl­ato-κ3 N 1,O:O′)diaqua­(μ-oxalato-κ4 O 1,O 2:O 1′,O 2′)lanthanum(III)] monohydrate]

The water-coordinated LaIII atom in the title compound, {[La(C5H4N3O2)(C2O4)(H2O)2]·H2O}n, is N,O-chelated by a 3-amino­pyrazine-2-carboxyl­ate ion; this ion links adjacent metal atoms to form a chain parallel to [010]. The oxalate ion serves as a bis-bidentate chelate that links adjacent metal atoms to form a chain parallel to [001]. The two bridging ions give rise to a layer motif parallel to (100) in which the LaIII atom exists in a distorted tricapped trigonal prismatic geometry. Extensive hydrogen bonding between the constituents stabilizes the structure