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The crystal structure of the new double CuII complex salt, [Cu(L)(H2O)2][Cu(L)]Br4·2H2O (L = 3,14-diethyl-2,6,13,17-tetra­aza­tri­cyclo­[16.4.0.07,12]docosane, C22H44N4) has been determined using synchrotron radiation. The asymmetric unit contains one half of a [Cu(L)(H2O)2]2+ cation, one half of a [Cu(L)]2+ cation (both completed by crystallographic inversion symmetry), two bromide anions and one water solvent mol­ecule. The CuII atom in the first complex exists in a tetra­gonally distorted octa­hedral environment with the four N atoms of the macrocyclic ligand in equatorial and two aqua ligands in axial positions, whereas the CuII atom in the second complex exists in a square-planar environment defined by the four nitro­gen atoms of the macrocyclic ligand. The two macrocyclic rings adopt the most stable trans-III configuration with normal Cu—N bond lengths from 2.016 (3) to 2.055 (3) Å and an axial Cu—O bond length of 2.658 (4) Å. The crystal structure is stabilized by inter­molecular hydrogen bonds involving the macrocycle N—H or C—H groups and the O—H groups of water mol­ecules as donor groups, and the O atoms of water mol­ecules and bromide anions as acceptor groups, giving rise to a one-dimensional network extending parallel to [100]. [ABSTRACT FROM AUTHOR]

Urea intercalated in montmorillonite (MMT) leads to considerable improvement of N efficiency in soils; however, there are no systematic approaches to elucidate the properties of urea intercalates within the interlayer space of swelling clays. This study focused on both the optimization of massive urea intercalation into MMT and the systematic characterization of urea-intercalated MMT (UCM). Anhydrous metal salts, which could allow optimal urea intercalation, were used for the first time to synthesize metal-urea complexes in a solid state. Massive intercalation of metal-urea complex into MMT was performed by simply mixing dehydrated MMT with a molten metal-urea complex containing excess urea at 105 ± 5°C. Successful complexation was confirmed by both the unique infrared spectra absorbance bands and the thermal behaviors of the coordinated urea molecules. The intercalation of metal-urea complexes into MMT was clearly demonstrated by a significant expansion of d001 spacing from 1.52 to 1.74 nm in Ca-UCM, as revealed by x-ray diffraction patterns. Infrared spectra also revealed that the intercalation of urea in the interlayer led to a distinct red shift in stretching vibration energy of the structural hydroxyl group of MMT from 3446 to 3483 cm-1 and from 3360 to 3400 cm-1. Experimental urea loading capacity was estimated to be 33.7% urea. All the intercalated urea molecules were found to be quickly and completely released by water molecules through ligand exchange, maintaining their effectiveness as a N source for crop cultivation. [ABSTRACT FROM AUTHOR]

In the title compound, [Cr(ONO)2(cyclam)]NO2 (cyclam is 1,4,8,11-tetraazacyclotetradecane, C10H24N2), the complex cation is located on a twofold symmetry axis. The central Cr atom has a distorted octahedral coordination, involving two Cr-O bonds, with the monodentate nitrite O atoms adopting a cis configuration, and four Cr-N bonds. The mean Cr-N and Cr-O distances are 2.0895 (14) and 1.9698 (14) Å. [ABSTRACT FROM AUTHOR]

Seven single crystals of fully dehydrated Ni2+-exchanged zeolite Y (Si/Al = 1.56) were prepared via cation exchange of Na75-Y (|Na75|[Si117Al75O384]-FAU) by flowing 0.05 M aqueous solutions of Ni(NO3)2·6H2O (pH 4.9 and 294 K) with various ion-exchange times. Their crystal structures were completely determined by single-crystal synchrotron X-ray diffraction techniques in cubic space group Fd3̅m at 100(1) K. In all seven structures, Ni2+ ions occupy sites I, I′, and II, and sometimes site II′ or a second site II, or both, preferring site I; residual Na+ ions in crystals 1 and 2 are found at site III and/or a second site III. The level of Ni2+ exchange monotonically increased from 75.2 to 89.6% [from 28.2(2) to 33.6(8) Ni2+ ions per unit cell] with increasing exchange time until 18 h. The dealumination of the zeolite frameworks was observed in the center of sodalite cavities after 24 h, suggesting that this process occurs during ion exchange, or subsequent dehydration. H+ ions are present in all seven crystals for a charge balance. Both the unit cell constants and Na+ contents decreased with increasing levels of Ni2+ exchange and ion-exchange time. [ABSTRACT FROM AUTHOR]

A relatively simple azetidine derivative with 2-aminoethyl and 2-pyridyl substituents functions as a tridentate ligand towards Cu(ii), giving species in which the CuN3unit is essentially planar and that, in the solid state, show a subtle balance between mononuclear and binuclear forms, allowing both to be simultaneously present in some lattices. Displacement of the ligand from Cu(ii) by the use of cyanide results in the formation of cyanogen, which appears to slowly react with the free amine to give an oxamidine characterised in its doubly-deprotonated form as its binuclear Ni(ii) complex. [ABSTRACT FROM AUTHOR]

Selective functionalisation of the tridentate ligand 1-(2-aminoethyl)-3-methyl-3-(2-pyridyl)azetidine at its terminal amino-nitrogen atom can be readily achieved by both reductive alkylation and simple alkylation reactions to give tri-, quadri-, quinque- and sexi-dentate derivatives. Simple alkylation by 2-picolinyl chloride provides the only example of a second reaction pathway where the azetidine ring of the reactant has undergone activation towards ring opening. Structural characterisation of the Cu(ii) complexes of these ligands has revealed several remarkable aspects of their solid-state coordination chemistry, including the formation of infinite helical aggregates through π-stacking and tetramerisation through carboxylate bridging, as well as further examples of the crystallisation of mixed species found to be rather common with complexes of the parent ligand. [ABSTRACT FROM AUTHOR]