The asymmetric unit of the title complex, [Ni(C12H8N2)3]S2O8·2C3H7NO·H2O, consists of a complex [Ni(phen)3]2+ cation and one isolated pds anion, with two DMF mol­ecules and one water mol­ecule as solvates (where phen is 1,10-phenanthroline, pds is the hexa­oxido-μ-peroxoido-di­sulf­ate dianion and DMF is dimethyl­formamide). The [Ni(phen)3]2+ cation is regular, with an almost ideal NiII bond-valence sum of 2.07 v.u. The group, as well as the water solvent mol­ecule, are well behaved in terms of crystallographic order, but the remaining three mol­ecules in the structure display different kinds of disorder, viz. the two DMF mol­ecules mimic a twofold splitting and the pds anion has both S atoms clamped at well-determined positions but with a not-too-well-defined central part. These peculiar behaviours are a consequence of the hydrogen-bonding inter­actions: the outermost SO3 parts of the pds anion are heavily connected to the complex cations via C—H⋯O hydrogen bonding, generating an [Ni(phen)3]pds network and providing for the stability of the terminal pds sites. Also, the water solvent mol­ecule is strongly bound to the structure (being a donor of two strong bonds and an acceptor of one) and is accordingly perfectly ordered. The peroxide O atoms in the pds middle region, instead, appear as much less restrained into their sites, which may explain their tendency to disorder. The cation–anion network leaves large embedded holes, amounting to about 28% of the total crystal volume, which are occupied by the DMF mol­ecules. The latter are weakly inter­acting with the rest of the structure, which renders them much more labile and, accordingly, prone to disorder.

The mol­ecular structure of the title compound, [Zn(CH3COO)2(C12H12N2)], consists of isolated mol­ecules bis­ected by a twofold rotation axis which goes through the ZnII cation and halves the organic base through the central C—C bond. The ZnII ion is coordinated by two N atoms from one mol­ecule of the aromatic base and four O atoms from two bidentate, symmetry-related acetate anions, which coordinate asym­metrically [Zn—O distances of 2.058 (2) and 2.362 (3) Å], while the two Zn—N bond distances are equal as imposed by symmetry [2.079 (2) Å]. The crystal structure is supported by a number of weak C—H⋯O inter­actions and C—H⋯π contacts, with no π–π inter­actions present, mainly hindered by the substituent methyl groups and the relative mol­ecular orientation. The result is a three-dimensional structure in which each mol­ecule is linked to eight different neighbors.

The title compound, C4H6N2S3, has two very similar mol­ecules per asymmetric unit. The nine non-H atoms in each mol­ecule are coplanar, both having comparable r.m.s. deviations of 0.002 Å. The main inter­est in the rather simple structure resides in a survey of very weak (in some cases, borderline) non-bonding inter­actions of various kinds, viz. S⋯S, C—H⋯π, π–π [centroid–centroid distance = 3.8958 (13) Å] and C—S⋯π [3.7271 (11) Å], which act as the major driving force for the arrangement of mol­ecules in the structure. The role of long, though highly directional, S⋯S contacts (d > 3.60 Å), and their relevance to the stability of the structure is discussed.

The mol­ecular structure of the title compound, NH4 +·C7H7O4S−, is featureless [the methoxy C atom deviating 0.173 (6) Å from the phenyl mean plane] with inter­atomic distances and angles in the expected ranges. The main feature of inter­est is the packing mode. Hydro­philic (SO3 and NH4) and hydro­phobic (PhOCH3) parts in the structure segregate, the former inter­acting through a dense hydrogen-bonding scheme, leading to a well connected two-dimensional structure parallel to (100) and the latter hydro­phobic groups acting as spacers for an inter­planar separation of c/2 = 10.205 (2) Å. In spite of being aligned along [110], the benzene rings stack in a far from parallel fashion [viz. consecutive ring centers determine a broken line with a 164.72 (12)° zigzag angle], thus preventing any possible π–π inter­action.

The title Nd complex [Nd2(C4H5O2)6(H2O)4]·2C5H6N6 is isotypic with two previously reported Dy and Ho isologues. It is composed of [Nd(crot)3(H2O)2]2 dimers [crot(onate) = but-2-enoate = C4H5O2], built up around symmetry centres and completed by 2,6-diamine­purine mol­ecules acting as solvates. The neodymium cations are coordinated by three chelating crotonato units and two water mol­ecules. One of the chelating carboxyl­ates acts also in a bridging mode, sharing one oxygen with both cations, and the final result is a pair of NdO9 tricapped prismatic polyhedra linked to each other through a central (Nd—O)2 loop. A most attractive aspect of the structures resides in the existence of a complex inter­molecular hydrogen-bonding interaction scheme involving two sets of tightly inter­linked, non-inter­secting one-dimensional structures, one of them formed by the [Nd(crot)3(H2O)2]2 dimers running along [100] and the second by the solvate mol­ecules evolving along [010].

The title centrosymmetric bimetallic complex, [Cu2(C2H3O2)4(C6H6N2O)4], is composed of two copper(II) cations, four acetate anions and four isonicotinamide (INA) ligands. The asymmetric unit contains one copper cation to which two acetate units bind asymmetrically; one of the Cu—O distances is rather long [2.740 (2) Å], almost at the limit of coordination. These Cu—O bonds define an equatorial plane to which the Cu—N bonds to the INA ligands are almost perpendicular, the Cu—N vectors subtending angles of 2.4 (1) and 2.3 (1)° to the normal to the plane. The metal coordination geometry can be described as a slightly distorted trigonal bipyramid if the extremely weak Cu—O bond is disregarded, or as a highly distorted square bipyramid if it is not. The double acetate bridge between the copper ions is not coplanar with the CuO4 equatorial planes, the dihedral angle between the (O—C—O)2 and O—Cu—O groups being 34.3 (1)°, resulting in a sofa-like conformation for the 8-member bridging loop. In the crystal, N—H⋯O hydrogen bonds occur, some of which generate a head-to tail-linkage between INA units, giving raise to chains along [101]; the remaining ones make inter-chain contacts, defining a three-dimensional network. There are in addition a number of C—H⋯O bonds involving aromatic H atoms. Probably due to steric hindrance, the aromatic rings are not involved in significant π⋯π inter­actions.

The title compound {[Cu2Ho2(C4H5O2)10(H2O)4]·3H2O}n, is a one-dimensional 3d/4f organic–inorganic hybrid complex, the HoIII member of the isotypic lanthanoid series with Ln = GdIII, ErIII and YIII. The structure shows an alternation of Cu2 and Ho2 dinuclear units bridged by the ligands and hydrogen bonds only. The chains are composed of Cu2 classical dinuclear η1:η1:μ2 fourfold bridges [Cu⋯Cu = 2.6417 (9) Å] and of Ho2 units bridged by two η2:η1:μ2 carboxyl­ate units. This results in distorted square-based pyramidal CuO5 units and irregular HoO9 units. The alternating Cu2 and Ho2 units are bridged into linear arrays along the a axis by a set of one η2:η1:μ2 carboxyl­ate O atom and two hydrogen bonds with Cu⋯Ho separations of 4.4883 (10) and 4.5086 (10) Å. The distance between adjacent chains, as calculated by the closest and furthest distances between two chains, covers the range 10–14 Å. The H atoms of the water mol­ecules could not be located, but the O⋯O separations for these species suggest the presence of O—H⋯O hydrogen bonds.

The title compound, [Cd2(C2H3O2)4(C12H8N2)2], consists of dimeric units built up around a crystallographic symmetry centre. Each cadmium(II) unit is chelated by a 1,10-phenanthroline (phen) group and two acetate ligands, one of which also acts as a bridge, linking both seven-coordinated cadmium(II) centres. The crystal structure is governed by a single π–π inter­action between stacked phen groups [centroid–centroid distance 3.5209 (11) Å], leading to a planar structure parallel to (010).

The present structural revision of the title compound, tetra­cadmium tetra­sulfite hexa­hydrate, [Cd4(SO3)4(H2O)5]·H2O, is a low-temperature upgrade (T = 100 K and R = 0.017) of the original room-temperature structure reported by Kiers & Vos [Cryst. Struct. Commun. (1978). 7, 399–403; T = 293 K and R = 0.080). The compound is a three-dimensional polymer with four independent cadmium centres, four sulfite anions and six water mol­ecules, five of them coordinated to two cadmium centres and the remaining one an unbound solvent mol­ecule which completes the asymmetric unit. There are two types of cadmium environment: CdO8 (through four chelating sulfite ligands) and CdO6 (by way of six monocoordinated ligands). The former groups form planar arrays [parallel to (001) and separated by half a unit cell translation along c], made up of chains running along [110] and [10], respectively. These chains are, in turn, inter­connected both in an intra­planar as well as in an inter­planar fashion by the latter CdO6 polyhedra into a tight three-dimensional framework. There is, in addition, an extensive network of hydrogen bonds, in which all 12 water H atoms act as donors and eight O atoms from all four sulfite groups and two water mol­ecules act as acceptors.

We present a new low-temperature refinement of disodium zinc bis­(sulfate) tetra­hydrate {systematic name: poly[tetra-μ-aqua-di-μ-sulfato-zinc(II)disodium(I)]}, [Na2Zn(SO4)2(H2O)4]n or Zn astrakanite, which is an upgrade of previously reported data [Bukin & Nozik (1974 ▶). Zh. Strukt. Khim. 15, 712–716]. The compound is part of an isostructural family containing the Mg (the original astrakanite mineral), Co and Ni species. The very regular ZnO(aqua)4O(sulfate)2 octa­hedra lie on centres of symmetry, while the rather distorted NaO(aqua)2O(sulfate)4 octa­hedra appear at general positions, linked into a three-dimensional network by the bridging water mol­ecules and the fully coordinated sulfate groups.