α‐Tris(2,4‐pentanedionato‐κ2O,O′)aluminium(III) at 240, 210, 180, 150 and 110 K: a new δ phase at 110 K

The crystal structure of the title compound, [Al(C₅H₇O₂)₃], has been investigated by a multi‐temperature measurement to provide information on thermal vibrations and disorder in the structure. At 110 K, the structure of a new δ polymorph could be determined. A disorder–order phase transition takes place between 150 and 110 K and is klassengleich. The unit‐cell volume increases by a factor of three and the diffraction pattern shows weak supercell reflections.     

α‐Tris(2,4‐pentanedionato‐κ2O,O′)chromium(III) at 290 and 110 K: a new δ phase at 110 K

The crystal structure of the title compound, [Cr(C₅H₇O₂)₃], has been determined at 290 and 110 K to provide information on thermal vibrations and disorder. The α polymorph at room temperature has been reported [Morosin (1965). Acta Cryst. 19 , 131–137]. The reinvestigation of this structure, presented here, indicates the presence of weak uninterpretable supercell reflections together with disorder streaks. The discussed structure can thus be considered as an average structure. After cooling to 110 K, a new δ polymorph was found, which is a superstructure of the α polymorph. The space group remains P2₁/c and the phase transition can therefore be considered as klassengleich. The unit‐cell volume increases by a factor of six, resulting in six independent molecules in the asymmetric unit.     

Directed anisotropy in bis(acetato‐κ2O,O′)diaquazinc(II) at 110 and 250 K

The molecule of the title compound, [Zn(C₂H₃O₂)₂(H₂O)₂], is located on a twofold axis in the crystal structure. The displacement parameters and the thermal expansion of the crystal show significant anisotropy. This is explained by the two‐dimensional hydrogen‐bonded structure, with only very weak interactions perpendicular to it. Besides the overall molecular motion, there are internal vibrations, which cause the Zn—O(carboxylate) bonds to fail the Hirshfeld rigid‐bond test. It is shown that this can be interpreted in terms of the steric strain in the four‐membered chelate ring due to the bidentate carboxylate coordination.     

Bis(μ‐acetato‐κ3O,O′:O′)bis[bis(acetato‐κ2O,O′)diaquadysprosium(III)] tetrahydrate

The title compound, [Dy₂(C₂H₃O₂)₆(H₂O)₄]·4H₂O, crystallizes in the form of dimeric units related by an inversion centre. Each cation is nine‐coordinate, binding to two water mol­ecules and three acetate groups, two of which are bidentate and the third tridentate. This last acetate group acts as a bridge between neighbouring metal atoms, leading to an intradimer Dy?Dy separation of 4.170 (1) Å.     

catena‐Poly[[(acetato‐κ2O,O′)triaquabarium(II)]‐μ3‐acetato‐κ4O:O,O′:O′]

The present form of barium acetate, formulated as [Ba(C₂H₃O₂)₂(H₂O)₃]_n, is the largest reported hydrate of the salt and this leads to a distinct structural behaviour setting it apart from the rest of the family. The compound is a linear polymer with a nine‐coordinate Ba(O_aqua)₃(O_acetate)₆ monomer unit. The non‐H part of the structure is ordered according to C2/m symmetry, while the disordered water H atoms only abide by this symmetry in a statistical sense. Each molecule is halved by a mirror plane bisecting the Ba centre, one water molecule and one acetate ligand, while containing the other acetate ligand. The chains are interconnected by a disordered water–water/acetate O—H...O hydrogen‐bonding network involving all water H atoms. The structure and stability of this phase are compared with the other known acetates of barium which differ in the degree of hydration.     

Bis(2,6‐diamino‐1H‐purin‐3‐ium) di‐μ‐croconato‐κ3O,O′:O′′;κ3O:O′,O′′‐bis[tetraaqua(croconato‐κ2O,O′)neodymium(III)]

The structure of the ionic title compound, (C₅H₇N₆)₂[Nd₂(C₅O₅)₄(H₂O)₈], consists of anionic dimers built around an inversion centre and is made up of an Nd^III cation, two croconate (croco) dianions and four water molecules (plus their inversion images), with two noncoordinated symmetry‐related 2,6‐diamino‐1H‐purin‐3‐ium (Hdap⁺) cations providing charge balance. Each Nd^III atom is bound to nine O atoms from four water and three croco units. The coordination polyhedron has the form of a rather regular monocapped square antiprism. The croconate anions are regular and the Hdap⁺ cation presents a unique, thus far unreported, protonation state. The abundance of hydrogen‐bonding donors and acceptors gives rise to a complex packing scheme consisting of dimers interlinked along the three crystallographic directions and defining anionic `cages' where the unbound Hdap⁺ cations lodge, linking to the mainframe via (N—H)_Hdap...O_water/croco and (O—H)_water...N_Hdap interactions.     

Tris(acetyl­acetonato‐κ2O,O′)(1,10‐phenanthroline‐κ2N,N′)erbium(III)

The title compound, [Er(C₅H₇O₂)₃(C₁₂H₈N₂)], is a mixed‐ligand metal–organic precursor for chemical vapour deposition, with the Er atom being eight‐coordinate. The coordination polyhedron, described as a distorted square anti­prism, is formed by three bidentate (chelating) acetyl­acetonate residues and a phenanthroline ligand in the apical positions. Mol­ecular assembly via C—H⋯O hydrogen bonds generates a sheet structure in the ac plane. Weak co‐operative C—H⋯π inter­actions form mol­ecular dimers and contribute to the stability of the inter­sheet packing. The supra­molecular assembly contains voids which form hydro­phobic porous channels, surrounded by a cluster of dimers.     

Tetrakis(2,2′‐bipyridine‐κ2N,N′)­tetrakis(μ‐salicyl­ato‐κ3O,O′:O′′)‐quadro‐tetrazinc(II) decahydrate

The title compound, [Zn₄(C₇H₄O₃)₄(C₁₀H₈N₂)₄]·10H₂O, crystallizes as a centrosymmetric tetranuclear cyclic complex containing four Zn^II atoms bridged by four carboxyl­ate groups from salicyl­ate ligands, with a syn–anti configuration. Each Zn^II atom has a distorted trigonal–bipyramidal coordination geometry, formed by two N atoms of a 2,2′‐bipyridine ligand and three O atoms from two salicyl­ate ligands. The complex is stabilized by intramolecular π–π interactions between pairs of bi­pyridine rings and a 16‐membered gear‐wheel‐shaped cyclic framework. The hydrogen‐bonding network is formed via the water mol­ecules.     

Bis(2,2′‐bi­pyridine‐κ2N,N′)(oxalato‐κ2O,O′)­cobalt(II) pentahydrate

The synthesis and crystal structure of the mononuclear title compound, [Co(C₂O₄)(C₁₀H₈N₂)₂]·5H₂O, is reported. The Co atom is six‐coordinated by two O atoms of a bidentate oxalate group and by four N atoms of two bi­pyridine ligands. The neutral [Co(C₂O₄)(C₁₀H₈N₂)₂] entities are connected by π–π stacking interactions of the aromatic systems into a two‐dimensional layer, interconnected through a ladder‐like hydrogen‐bonding pattern of solvate water mol­ecules.     

Bis(2‐amino‐1H‐benzimidazol‐3‐ium) tetrakis(μ‐but‐2‐enoato)‐κ4O:O′;κ3O,O′:O;κ3O:O,O′‐bis[bis(but‐2‐enoato‐κ2O,O′)holmium(III)]

The title ionic compound, (C₇H₈N₃)₂[Ho₂(C₄H₅O₂)₈], is constructed from two almost identical independent centrosymmetric anionic dimers balanced by two independent 2‐amino‐1H‐benzimidazol‐3‐ium (Habim⁺) cations. The asymmetric part of each dimer is made up of one Ho^III cation and four crotonate (crot or but‐2‐enoate) anions, two of them acting in a simple η²‐chelating mode and the remaining two acting in two different μ₂:η² fashions, viz. purely bridging and bridging–chelating. Symmetry‐related Ho^III cations are linked by two Ho—O—Ho and two Ho—O—C—O—Ho bridges which lead to rather short intracationic Ho...Ho distances [3.8418 (3) and 3.8246 (3) Å]. In addition to the obvious Coulombic interactions linking the cations and anions, the isolated [Ho₂(crot)₈]²⁻ and Habim⁺ ions are linked by a number of N—H...O hydrogen bonds, in which all N—H groups of the cation are involved as donors and all (simple chelating) crot O atoms are involved as acceptors. These interactions result in compact two‐dimensional structures parallel to (110), which are linked to each other by weaker π–π contacts between Habim⁺ benzene groups.     

(2,2′‐Biquinoline‐κ2N,N′)bis(nitrato‐κ2O,O′)copper(II)

In the title monomer, [Cu(NO₃)₂(C₁₈H₁₂N₂)], the six‐coordinated Cu^II atom lies on a twofold axis which bisects one of the ligands (a chelating biquinoline) and duplicates the remaining ligand, a chelating nitrate. The latter binds in a very asymmetric way, consistent with a Jahn–Teller distortion in the coordination polyhedron which, due to the triple chelation, is extremely distorted and difficult to describe in terms of any regular model.     

(μ‐1,2‐Dimethoxyethane‐κ2O:O′)bis[(1,2‐dimethoxyethane‐κ2O,O′)tris(1,1,1,5,5,5‐hexafluoro‐4‐oxopent‐2‐en‐2‐olato‐κ2O,O′)cerium(III)]

A previous analysis [Fatila et al. (2012). Dalton Trans. 41 , 1352–1362] of the title complex, [Ce₂(C₅HF₆O₂)₆(C₄H₁₀O₂)₃], had identified it as Ce(hfac)₃(dme)_1.5 according to the ¹H NMR integration [hfac = 1,1,1,5,5,5‐hexafluoroacetylacetonate (1,1,1,5,5,5‐hexafluoro‐4‐oxopent‐2‐en‐2‐olate) and dme = 1,2‐dimethoxyethane]; however, it was not possible to determine the coordination environment unambiguously. The structural data presented here reveal that the complex is a binuclear species located on a crystallographic inversion center. Each Ce^III ion is coordinated to three hfac ligands, one bidentate dme ligand and one monodentate (bridging) dme ligand, thus giving a coordination number of nine (CN = 9) to each Ce^III ion. The atoms of the bridging dme ligand are unequally disordered over two sets of sites. In addition, in two of the –CF₃ groups, the F atoms are rotationally disordered over two sets of sites. This is the first crystal structure of a binuclear lanthanide β‐diketonate with a bridging dme ligand.     

Bis(1‐ferrocenylbutane‐1,3‐dionato‐κ2O,O′)copper(II) and bis­(1,3‐diferrocenylpropane‐1,3‐dionato‐κ2O,O′)­copper(II)

The title compounds, [CuFe₂(C₅H₅)₂(C₉H₈O₂)₂], (I), and [CuFe₄(C₅H₅)₄(C₁₃H₉O₂)₂], (II), are four‐coordinate square‐planar copper(II) complexes with two bidentate 1‐ferrocenylbutane‐1,3‐dionate or 1,3‐diferrocenylpropane‐1,3‐dionate ligands, respectively. The copper ion in (I) lies on an inversion centre, with one‐half of the mol­ecule in the asymmetric unit, while in (II), there are two independent half mol­ecules in the asymmetric unit, with the copper ions also situated on inversion centres. The ferrocene substituents in (I) are in an anti arrangement. The mol­ecules assemble in the crystal structure in layers with ferrocene groups at the surface. The pairs of ferrocene substituents on each ligand in complex (II) are syn and these adopt an anti arrangement with respect to the pair on the other diketonate ligand. As found in (I), complexes assemble in a layered structure with ferrocene‐coated surfaces.     

Hexaamminecobalt(III) aquabis(nitrilotriacetato‐κ4N,O,O′,O′′)gadolinate(III) octahydrate

Crystals of the title compound, [Co(NH₃)₆][Gd(C₆H₆NO₆)₂(H₂O)]·8H₂O, were synthesized in and collected from aqueous solution. The hexaamminecobalt(III) cation has the expected octahedral geometry, while the Gd coordination sphere has the geometry of a tricapped trigonal prism, with the two nitrilo­tri­acetate N atoms and one water mol­ecule occupying the capping positions.     

A novel titanium–μ‐O–zirconium complex: bis(μ‐methyliminodiethanolato‐1κ3O,N,O′;1:2κ2O)(methyliminodiethanolato‐2κ3O,N,O′)dipropanolato‐1κO,2κO‐titanium(IV)zirconium(IV)

The title compound, [TiZr(C₅H₁₁NO₂)₃(C₃H₇O)₂], contains three methyl­imino­diethano­late ligands, two in different μ‐oxo bridging coordination modes and one bound only to the Ti atom. The Ti and Zr atoms have distorted octahedral and pentagonal–bipyramidal coordinations, respectively, which share edges. As well as some conformational disorder in the carbon chains, there is chemical disorder at one Ti site, with a mix of n‐ and isopropanolate ligands.     

(2,2′‐Bipyridyl‐κ2N,N′)­bis­(salicyl­ato‐κ2O,O′)­zinc(II)

The asymmetric unit of the title compound, [Zn(C₇H₅O₃)₂(C₁₀H₈N₂)], contains one monomeric zinc complex. The Zn atom is coordinated to one 2,2′‐bipyridyl ligand via both N atoms and to two salicyl­ate anions (Hsal⁻) in a bidentate chelating manner involving carboxyl­ate O‐atom coordination. The complex exhibits a distorted octahedral geometry about the Zn^II atom, with the `apical' positions occupied by one of the two N atoms of the bipyridyl ligand and an O atom from one Hsal<sup>−</sup> ligand; the Zn atom is 0.168 (1) Å out of the `basal' plane. Two intramolecular six‐membered hydrogen‐bonded rings are present, generated from interactions between the carboxyl and hydroxyl groups of the salicyl­ate ligands. The crystal packing is governed by weak C—H⋯O and C—H⋯π interactions.     

Sodium tris(acetato‐κ2O,O′)dioxidoamericate(VI) and guanidinium tris(cyclopropanecarboxylato‐κ2O,O′)dioxidoamericate(VI)

The title compounds, Na[{AmO₂}(C₂H₃O₂)₃], (I), and (CH₆N₃)[{AmO₂}(C₄H₅O₂)₃], (II), contain complex anions in which AmO₂²⁺ cations are surrounded by three bidentate‐chelating carboxylate groups. The atoms of the AmO₂ group and the Na atoms in (I) are situated on threefold axes. All the atoms in (II) occupy general positions. Both compounds are isomorphous with earlier studied analogous compounds of previous members of the actinide (An) series.     

Bis[diaquabis(2,2‐bipyridine N,N′‐dioxide‐κ2O,O′)cobalt(II)] ξ‐octamolybdate dihydrate

The title organic–inorganic hybrid compound, [Co(C₁₀H₈N₂O₂)₂(H₂O)₂]₂[Mo₈O₂₆]·2H₂O, consists of [Co(bpdo)₂(H₂O)₂]²⁺ (bpdo is 2,2‐bipyridine N,N′‐dioxide) and ξ‐[Mo₈O₂₆]⁴⁻ groups in a 2:1 ratio, plus two water solvent molecules. The independent Co atom in the cation is coordinated by four O atoms from two bpdo ligands and two water molecules, in a distorted octahedral geometry. The counter‐anions, built up around a symmetry center, are linked by solvent water molecules through O—H...O hydrogen bonds to generate two‐dimensional layers, which are in turn linked by coordinated water molecules from the cationic units through further O—H...O hydrogen bonds, forming a three‐dimensional supramolecular structure.     

catena‐Poly­[[bis(pentane‐2,4‐dionato‐κ2O,O′)­cobalt(II)]‐μ‐4,4′‐methylene­dianiline‐κ2N:N′]

In the title compound, [Co(C₅H₇O₂)₂(C₁₃H₁₄N₂)]_n or [Co(acac)₂(dadpm)]_n, where acac is acetyl­acetonate and dadpm is 4,4′‐methylenedianiline, the Co atom is on a centre of symmetry and is octahedrally coordinated by four O atoms from two acac anions and by two N atoms from two dadpm ligands. Each dadpm ligand, which has a twofold axis passing through its methyl­ene C atom, bridges two Co atoms to form a spiral polymeric chain. Neighbouring chains connect via hydrogen bonds to form a two‐dimensional network.     

(Acetato‐κ2O,O′)dihydroxidoytterbium(III) hemihydrate

The title compound, [Yb(C₂H₃O₂)(OH)₂]·0.5H₂O, was obtained via hydrothermal reaction of Yb(CH₃COO)₃·H₂O with NaOH at 443 K. The compound forms two‐dimensional layers with six crystallographically independent Yb^III atoms. Four of these form YbO₈ coordination polyhedra, while the coordination number of the remaining two Yb^III atoms is 7. Five of these coordination polyhedra are interconnected mainly via hydroxide groups, as they build a narrow inner layer that extends infinitely within the ab plane. The sixth Yb^III atom resides outside this inner layer and builds a terminal YbO₈ coordination polyhedron on the layer surface. Its coordination environment comprises four carboxylate O atoms belonging to three different acetate entities, three hydroxide groups and one water molecule. Adjacent layers experience weak interactions via hydrogen bonds. The Yb—O distances lie in the range 2.232 (4)–2.613 (5) Å.