Structural aspects of some 2:1 dipyridylamine complexes of some copper(II) salts: An interesting new polymorph of the binuclear carbonate/perchlorate tetrahydrate adduct

Recent work has described the structural characterization of the complexes View the MathML sourceCu2(CO3)X2′:dpyam:H2O (1:4:4), X′ = ClO4, BF4, ‘dpyam’ = dipyridylamine, as a pair of triclinic Z = 1 isomorphs, the cations being modelled in terms of pairs of copper atoms bridged by a carbonate ion disordered about a crystallographic inversion centre. This work has been revisited in the course of describing a new polymorph of the perchlorate in a triclinic cell of twice the size, in which the carbonate unit, now non-disordered, bridges a pair of crystallographically independent copper atoms which display distinctly different coordination environments, one close to the square-pyramidal norm, the other not. Studies of adducts of the form [(dpyam)2CuX]X′(·nH2O) are also recorded. The X/X′ = propionate/iodide adduct is found to be isomorphous with its acetate/BF4 but, interestingly, not its propionate/Cl counterpart. ‘Low’-temperature redeterminations of the NCO/Cl · 4H2O and nitrite/ClO4 adducts are also recorded, enabling definition of the hydrogen-bonding scheme in the former.