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

Abstract

The dark-red title complex crystallized from an equimolar methanol solution of (E)-5-(ethylamino)-4-methyl-2-[(pyridin-2-yl)diazenyl]phenol and CuCl2(phen) (phen = 1,10-phenanthroline) as a centrosymmetric dimer, [CuCl(C14H15N4O)]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·4H2O, 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. A46, 194–201].

Insight into the Spatial Arrangement of the Lysine Tyrosylquinone and Cu2+ in the Active Site of Lysyl Oxidase-like 2

“…The ORTEP representation of the crystal structure of Complex 3 with atomic numbering scheme is shown in Figure 5B. The crystal structure of Complex 3 revealed a centrosymmetric Cu(II) dimer with a double axial−equatorial chlorido bridge, where another molecule of 1 replaced the original 1,10−phenanthroline ligand of Cu(II) [30]. This was not expected as we previously obtained crystals of TPQ−2HP complex with 1,10−phenanthroline−Cu(II) in Complex 4 (Figure 5C) [29].…”

“…Due to the precipitation of protein at liquid N 2 temperature, it was not possible to obtain EPR spectrum of 2HP-inhibited LOXL2. Since we obtained the crystal structure of Complex 3 rather than Complex 2 (Figure 5A,B) [30], we conducted comparative EPR spectroscopy of Complex 3 and Complex 4 (Figure 5B,C) both in a solid state and in solution (DMSO) to define the coordination geometry and electronic structure of Complex 3 and examine the effect of double chlorido bridges as opposed to 1,10-phenanthroline ligand (two Ns). Figure 6 shows the experimental spectra of Complex 3 and Complex 4 in a solid state as well an overlay between experimental (in black) and simulated (in red) data of 2 mM solutions of 3 and 4 in DMSO.…”

“…Experimental details for synthesis of 1, Complexes 2 and 3 and crystallization and X-ray crystallography of Complex 3 is described elsewhere [30].…”

“…Bond length (Å) and bond angles ( • ) of Complex 3 and Complex 4 at Cu(II) coordination.sites[29,30].…”