Crystal structures of di-μ-chlorido-bis({( E )-5-(ethylamino)-4-methyl-2-[(pyridin-2-yl)diazenyl]phenolato}copper(II)) and chloridobis(1,10-phenanthroline)copper(II) chloride tetrahydrate

The dark-red title complex crystallized from an equimolar methanol solution of ( E )-5-(ethylamino)-4-methyl-2-[(pyridin-2-yl)diazenyl]phenol and CuCl 2 (phen) (phen = 1,10-phenanthroline) as a centrosymmetric dimer, [CuCl(C 14 H 15 N 4 O)] 2 . The Cu atoms are bridged by two Cl ligands and have a slightly distorted square-pyramidal coordination, where two N atoms from the azo and the pyridine moieties, a phenolic O and a Cl atom comprise the base and the other Cl occupies the apex position. The apical Cu—Cl bond, 2.6192 (4) Å, is longer than the basal one, 2.2985 (3) Å, due to Jahn–Teller distortion. The dimers are associated via weak intermolecular hydrogen bonds and π–π stacking interactions between phenyl and pyridine rings. A monomeric by-product of the same reaction, [CuCl(phen) 2 ]Cl·4H 2 O, has a trigonal–bipyramidal coordination of Cu with equatorial Cl ligand, and extensive outer-sphere disorder. In the structure of 4 , the packing of cations leaves continuous channels containing disordered Cl − anions and solvent molecules. The identity of the solvent (water or a water/methanol mixture) was not certain. The disordered anion/solvent regions comprise 28% of the unit-cell volume. The disorder was approximated by five partly occupied positions of the Cl − anion and ten positions of O atoms with a total occupancy of 3, giving a total of 48 electrons per asymmetric unit, in agreement with the integral electron density of 47.8 electrons in the disordered region, as was estimated using the BYPASS-type solvent-masking program [van der Sluis & Spek (1990). Acta Cryst. A 46 , 194–201].