Basem F. Ali

Interconversion of copper(II) to copper(I): synthesis, characterization of copper(II) and copper(I) 2,2′-biquinoline complexes and their microbiological activity

The complexes [Cu(biq)2]Cl2 and [Cu(biq)2]BF4·biq (biq = 2,2′-biquinoline) have been prepared and characterized. The interconversion to copper(I) complex [Cu(biq)2]BF4·biq, from [Cu(biq)2]Cl2 has been established. The new complexes have been characterized by elemental analysis, conductivity and magnetic measurements, IR, UV-vis and 1H- and 13C-NMR spectroscopy. The X-ray analysis of the complex [Cu(biq)2]BF4·biq supports the assumption of the interconversion of copper(II) to copper(I) in this case. The crystal structure shows that geometry around the metal is severely distorted from Td, and displays many supramolecular motifs incorporating both hydrophobic (aryl···aryl) and hydrophilic (C–H···F) intermolecular interactions. The microbiological activity of the complexes against bacteria and fungi was found to be high against Candida albicans, and slight to moderate against bacteria. The antimicrobial activity of [Cu(biq)2]BF4·biq was slightly better than that observed for [Cu(biq)2]Cl2 against both bacteria and fungi.

Bis(2-amino-3,5-dibromo-4,6-dimethyl­pyridinium) hexa­bromido­stannate(IV)

In the title compound, (C(7)H(9)Br(2)N(2))(2)[SnBr(6)], the cations and centrosymmetric anions are stacked in alternating layers that show no significant intermolecular interactions within each stack. Extensive cation...[SnBr(6)](2-) interactions are found, represented by short Br...Br interactions, along with different Br...HN (pyridine and amine) and weaker Br...HCH(2) hydrogen-bonding motifs.

Crystal supramolecularity: extended aryl embraces in dimorphs of [Cu(1,10-phen)2I]I3

The crystal structures of monoclinic and triclinic dimorphs of [Cu(phen)2I]+ I3- are reported, and the crystal packing of each is analysed. Local interactions between [Cu(phen)2I]+ cations are parallel fourfold aryl embraces (P4AE) of the phen ligands, supplemented by offset face-to-face interactions, to form layers of embracing cations. The tri-iodide ions are associated with the faces and the peripheries of the phen ligands, and recurring motifs are identified. Calculations of the intermolecular energies for the [Cu(phen)2I]+...[Cu(phen)2I]+ motifs and the [Cu(phen)2I]+...I3- motifs and the negligible I3-...I3- interactions are presented. While the energy contributions for the two structures have significant differences, the totals are very similar, consistent with the dimorphism. There are significant differences in molecular coordination stereochemistry for [Cu(phen)2I]+ in the two structures, and we conclude that this difference is a consequence of the alternative crystal packings.

Bis-(2-amino-6-methyl-pyridinium) tetra-bromido-cuprate(II).

In the crystal structure of the title compound, (C6H9N2)2[CuBr4], the geometry around the Cu atom is intermediate between tetrahedral (Td) and square planar (D4h). Each [CuBr4]2− anion is connected non-symmetrically to four surrounding cations through N—H⋯X (pyridine and amine proton) hydrogen bonds, forming chains of the ladder-type running parallel to the crystallographic b axis. These layers are further connected by means of offset face-to-face interactions (parallel to the a axis), giving a three-dimensional network. Cation π–π stacking [centroid separations of 3.69 (9) and 3.71 (1) Å] and Br⋯aryl interactions [3.72 (2) and 4.04 (6) Å] are present in the crystal structure. There are no intermolecular Br⋯Br interactions.

Bis(2-amino-4-methyl-pyridinium) tetra-chloridocuprate(II).

The asymmetric unit of the title compound, (C6H9N2)2[CuCl4], consists of one cation and one half-anion, bisected by a twofold rotation axis through the metal center. The anion exhibits a geometry that is intermediate between a Td and D 4h arrangement about the Cu atom. The crystal structure contains chains of cations alternating with stacks of anions. The cationic groups interact via offset face-to-face π–π stacking, forming chains running along the c axis. The anion stacks are parallel to the cation chains, with no significant inter- nor intrastack Cl⋯Cl interactions. There are several anion–cation hydrogen-bonding interactions of the (N—H)pyridine⋯Cl and (N—H)amino⋯Cl types, connecting the chains of cations to the stacks of anions. Both the N—H⋯Cl and π–π stacking interactions [centroid–centroid distances 3.61 (8) and 3.92 (2) Å] contribute to the formation of a three-dimensional supramolecular architecture.

3-Ammonio-pyridinium tetra-bromido-mercurate(II) monohydrate.

The asymmetric unit of the title compound, (C5H8N2)[HgBr4]·H2O, consists of one cation, one anion and one water molecule. The anion exhibits a distorted tetrahedral arrangement about the Hg atom. The crystal structure contains alternating sheets of cations (in the ac plane) and stacks of anions. Several strong hydrogen-bonding interactions (pyN—H⋯Br and C—H⋯Br; py is pyridine), along with O—H⋯Br interactions, connect the sheets of cations to the stacks of anions. Cation–cation π–π stacking is also present (C⋯C distances in the range 3.424–3.865 Å). The shortest Br⋯Br distance is 3.9527 (9) Å.

Bis(2,6-dimethyl­pyridinium) tetra­bromido­cobaltate(II)

In the crystal structure of the title compound, (C7H10N)2[CoBr4], the [CoBr4]2− anion is connected to two cations through N—H⋯Br and H2C—H⋯Br hydrogen bonds to form two-dimensional cation–anion–cation layers normal to the crystallographic b axis. Interactions of the π–π type are absent between cations in the stacks [centroid–centroid separation = 5.01 (5) Å]. Significant intermolecular Br–aryl interactions are present in the structure, especially an unusually short Br–ring centroid interaction of 3.78 (1) Å. The coordination geometry of the anion is approximately tetrahedral and a twofold rotation axis passes through the Co atom.

Synthesis and characterization of metal 2-pyridine carboxaldehyde-N-methyl-N-2-pyridyl hydrazone complexes and their microbiological activity

Complexes of Cu(II), Mn(II), Co(II), Ni(II), Hg(II), Cd(II) and Rh(III) with 2-pyridine carboxaldehyde-N-methyl-N-2-pyridylhydrazone ( pamph) have been prepared and characterized. The new complexes have been characterized by elemental analysis, conductivity and magnetic measurements, IR, UV–vis and 1H NMR spectroscopic methods. The microbiological activity of the complexes was investigated against bacteria and fungi. Most of the complexes studied appear to be active against bacteria while all are active against fungi. The Cu, Cd and Hg complexes exhibit the highest activity against both bacteria and fungi.

Substituted dipyridylpyridazine rhodium(III) complexes

Abstract3,6-Bis(2′-pyridyl)pyridazine derivatives (n-dppn) react with hydrated rhodium(III) chloride and bromide (prepared in situ) to give cis-[Rh(n-dppn)2Cl2]PF6·xH2O (n = 5, 6, 7, 8) and cis-[Rh(n-dppn)2Br2]Br·xH2O (n = 5, 7) complexes, which have been characterized by elemental analyses, conductivity measurements, i.r., electronic and 1H- and 13C-n.m.r. spectra.

Bis(2,4,6-trimethyl-pyridinium) tetra-bromidozincate.

In the title compound, (C8H12N)2[ZnBr4], the coordination geometry of the anion is approximately tetrahedral. The Zn—Br bond lengths range from 2.3901 (19) to 2.449 (2) Å and the Br—Zn—Br angles range from 107.09 (8) to 112.48 (8)°. In the crystal, each [ZnBr4]2− anion is connected to four cations through two N—H⋯Br and two C—H⋯Br hydrogen bonds, forming two-dimensional ⋯(cation)2⋯anion⋯(cation2)⋯ sheets parallel to the bc plane. Within each sheet, the anions are arranged in stacks with no significant inter-anion Br⋯Br interactions [the shortest being > 4.3 Å], while the cations are in chains, with weak π–π stacking interactions [centroid–centroid distance = 3.991 Å] between cations interacting with the same anion.