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The crystal structures are reported of trans-dioxocyclam dihydrate, C10H20N4O2·2H2O, a structural isomer of the well known cis-dioxocyclam, and of its novel Ni complex, (1,4,8,11-tetra­aza­cyclo­tetra­decane-2,9-dionato-κ4 N)­nickel(II) dihydrate, [Ni(C10H18N4O2)]·2H2O, the first example of a trans­ition metal complex of this ligand. Both mol­ecules lie on crystallographic centres of inversion. The free ligand has two of its N atoms turned outwards from the ring and hydrogen bonded to water mol­ecules. A major conformational change takes place in the complex in which the ligand binds in a trans tetradentate fashion, as suggested by the electronic spectrum. The nickel(II) ion is low spin, although the electronic spectrum of the complex in water indicates an equilibrium mixture of low-spin and high-spin species. The irreversible electrochemical oxidation of [Ni L1] ( L1 is deprotonated trans-dioxocyclam, C10H18N4O2) in water occurs at a potential of 0.964 V [ versus SHE (standard hydrogen electrode)], which is very similar to that for the Ni- cis-dioxocyclam complex. [ABSTRACT FROM AUTHOR]

The preparation and crystal structures of (4,11-di­benzyl-1,4,8,11-tetra­aza­bi­cyclo­[6.6.2]­hexa­decane-κ4 N)copper(I) hexa-fluorophosphate, [Cu(C26H38N4)]PF6, and acetonitrile(4,11-dibenzyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-κ4 N)-copper(II) bis(hexafluorophosphate), [Cu(C2H3N)(C26H38-N4)](PF6)2, are described. The CuI ion is tetracoordinated in a very distorted tetrahedron, while the CuII analogue is pentacoordinated in a square pyramid. [ABSTRACT FROM AUTHOR]

The title 2,6-disubstituted pyridine, C41H61NO4, with a crystallographic twofold axis, has an arrangement of mol­ecules well organized to undergo multiple cyclo­metallation reactions. [ABSTRACT FROM AUTHOR]

The title compound, CsNa(CHO2)2, was obtained from the crystallization of caesium formate in a glass container. It has a complex structure, with sodium ions octa­hedrally coordinated and caesium ions irregularly eight-coordinated by the formate O atoms. One Cs cation and four formate C atoms have site symmetry m and one Na cation has site symmetry , resulting in the unusual situation of Z = 12 for an ortho­rhom­bic structure. [ABSTRACT FROM AUTHOR]