Morsy A. M. Abu-Youssef

Synthesis, Structural Characterisation, and Monte Carlo Simulation of the Magnetic Properties of the 3D-Stacked Honeycomb Csn[{Mn(N3)3}n] and the Irregular Double Chain [{N(C2H5)4}n][{Mn2(N3)5(H2O)}n]

Two new polymeric manganese-azido systems with formula Cs(n)-[[Mn(N3)3]n] (1) and [[N(C2H5)4]n][[Mn2-(N3)5(H2O)]n] (2) were synthesised and structurally characterised. Compound 1 crystallises in the P2(1)/n group and consists of a three-dimensional system with end-to-end and end-on azido bridges with the caesium atoms in the holes of the net. Magnetically, compound 1 is a rare case of a three-dimensional network with alternate ferro-antiferromagnetic interactions. Compound 2 crystallises in the P1 group and consists of double chains of manganese atoms bridged by end-on and, the exceptional, (mu-1,1,1)-azido bridges. Magnetically, compound 2 shows net ferromagnetic behaviour. Exact fit of the magnetic data was performed for the two compounds by means of Monte Carlo simulations based on the Metropolis algorithm on sets of 10 x 10 x 10 (1) and 1 x 1 x 320 (2) S = 5/2 classical spin centres.

Synthesis, a case of isostructural packing, and antimicrobial activity of silver(I)quinoxaline nitrate, silver(I)(2,5-dimethylpyrazine) nitrate and two related silver aminopyridine compounds

The synthesis and low temperature crystal structures of [Ag(quinoxaline)]n(NO3)n, 1, [Ag(2,5-dimethylpyrazine)(NO3)]n, 2 and [Ag4(3-aminopyridine)4(NO3)4]n 3 are presented. The quinoxaline compound forms a 1D coordination polymer with the characteristic linear 2-coordination figure of silver(I), the N-Ag-N angle being 164.2(1) degrees, and only weak silver-nitrate interactions. In addition there is an interaction giving pairs of parallel chains as the main structural theme. The 2,5-dimethylpyrazine compound has approximately trigonal-planar coordination, also binding one nitrate at the relatively short Ag-O distances 2.444(3) angstroms and 2.484(3) angstroms, respectively, for the two crystallographically different silver atoms. This also results in a 1D coordination polymer that, despite the large differences in the Ag(I) coordination environment, is isostructural with 1. [Ag4(3-aminopyridine)4(NO3)4]n 3 forms a 2D coordination polymer by bridging nitrate ions. The antimicrobial activity of 1-3, and also of [Ag3(2-aminopyridine)4](NO3)3, 4 was screened for 13 different pathogens and substantial activity was shown for 1 against Escherichia coli and Pseudomonas aeruginosa (MIC 4 microg cm(-3)) and somewhat lower activity was registered against Sarcina lutea and Salmonella typhi for 1, Bordetella bronchiseptica for 2, Salmonella typhi and Pseudomonas aeruginosa for 3, and Escherichia coli and Shigella sonnie for 3 (MIC 8 microg cm(-3)). Only low activity was shown against the yeast Candida albicans for 1, 2 and 4 whereas no activity against this pathogen was registered for 3.

An unusual 3D-topology and dominant ferromagnetic couplings in two Cu(II)–azide coordination polymers

The coordination polymers [(Cu(N(3))(2))(2)Cu(N(3))(2)(methylpyrazine)(2)](n) 1 and [Cu(4-bromopyridine)(N(3))(2)](n) 2, were prepared from NaN(3), Cu(NO(3))(2).3H(2)O and nitrogen-containing heterocycles. 1 contains a three- and four-connected 3D (4.10(2))(2)(4(2).10(4))-dmd-net based on tetrahedral and trigonal planar nodes, whereas 2 is a sheet-structure formed by a uninodal three-connected 8(2).4 2D-net with additional BrBr (mean 3.903(2) A) and BrN(azide) (3.035(5) A) contacts. Both compounds contain end-on-type azide bridges, and 2 has in addition one end-to-end bridge as well. The corresponding magnetic interactions are J(1,2) = +14.9(6) cm(-1) for the end-on azido interactions in 1 with an additional -1.7 cm(-1) coupling through the pyrazine, and J(1) = 36(6) cm(-1) for the end-on azido interactions and J(2) = 2.5(1) cm(-1) for the orthogonal end-to-end azido interactions found in 2.

Two new polymeric cadmium(II) complexes containing end-to-end bridging azido or thiocyanato ligands with different topologies

Abstract Two new polymeric cadmium(II) complexes; [Cd(3,5-DMP)2(N3)2] (1) and [Cd(4-Brpy)2(NCS)2] (2), where 3,5-DMP=3,5-dimethylpyridine and 4-Brpy=4-bromopyridine, have been synthesized and characterized. IR spectral data suggest end-to-end bridging azido and thiocyanato ligands. X-ray crystal structure determination has shown the 1-D complex 1 to contain each cadmium octahedrally coordinated by two double μ(1,3)-bridging azides and the other two sites are occupied by two pyridine ligands in a cis-arrangement. The CdCd distances in the Cd2(N3)2 eight membered rings are 5.142(2) and 5.152(2) A, the azide ligands are almost symmetrical and linear [NN distances: 1.167(5)–1.182(5) A; ∠NNN=176.7(4)° and 177.6(4)°]. In complex 2 each octahedrally cadmium atom is coordinated by two trans pyridine ligands and two trans nitrogen or sulfur atoms from four μ(N,S) bridging thiocyanato groups. The other end atoms of these four thiocyanato ligands bind four different cadmium atoms giving a 2-D layer structure.

Synthesis, Crystal Structure, Quantum Chemical Calculations, DNA Interactions, and Antimicrobial Activity of [Ag(2-amino-3-methylpyridine)2]NO3 and [Ag(pyridine-2-carboxaldoxime)NO3]

[Ag(2-amino-3-methylpyridine)(2)]NO(3) (1) and [Ag(pyridine-2-carboxaldoxime)NO(3)] (2) were prepared from corresponding ligands and AgNO(3) in water/ethanol solutions, and the products were characterized by IR, elemental analysis, NMR, and TGA. The X-ray crystal structures of the two compounds show that the geometry around the silver(I) ion is bent for complex 1 with nitrate as an anion and trigonal planar for complex 2 with nitrate coordinated. ESI-MS results of solutions of 2 indicate the independent existence in solution of the [Ag(pyridine-2-carboxaldoxime)](+) ion. The geometries of the complexes are well described by DFT calculations using the ZORA relativistic approach. The compounds were tested against 14 different clinically isolated and four ATCC standard bacteria and yeasts and also compared with 17 commonly used antibiotics. Both 1 and 2 exhibited considerable activity against S. lutea , M. lutea , and S. aureus and against the yeast Candida albicans , while 2-amino-3-methylpyridine is slightly active and pyridine-2-carboxaldoxime shows no antimicrobial activity. In addition, the interaction of these metal complexes with DNA was investigated. Both 1 and 2 bind to DNA and reduce its electrophoretic mobility with different patterns of migration, while the ligands themselves induce no change.

Synthesis and crystal structure of three new 2D polymeric cadmium(II) complexes of some pyridine derivatives with different cadmium(II)–azide topologies

Three new polymeric complexes [Cd(2-Acpy)(N3)2]n1, [Cd(4-Acpy)2(N3)2]n2 and [Cd3(4-Brpy)4(N3)6]n3 (2-Acpy = 2-acetylpyridine, 4-Acpy = 4-acetylpyridine, and 4-Brpy = 4-bromopyridine) have been synthesized and characterized by single crystal X-ray diffraction. The coordination environment of the cadmium atom in all the complexes is distorted octahedral with two-dimensional polynuclear layers. The cadmium atoms are linked by both μ-1,1 and μ-1,3 in 1, by only μ-1,3 in 2 and by μ-1,1 and μ-1,1,3 azide bridges in 3 giving different cadmium(II)–azide topologies.

Synthesis, spectral and structural characterization of a monomeric chloro complex of Zinc(II) with picolinic acid, [Zn(C5H4NCO2H)(C5H4NCO2)Cl]

Abstract The title compound of zinc(II) and picolinic acid was synthesized and characterized by X-ray crystallographic and spectroscopic methods. In the structure of [Zn(C5H4NCO2H)(C5H4NCO2)Cl], each zinc atom is coordinated by two nitrogen atoms at ZnN distances of 2.040(8) A and two oxygen atoms, O(1), at ZnO bond lengths of 2.152(5) A, belonging to two picolinate ligands. Coordination number five of the zinc atom is completed by a ZnCl bond [2.221 (3) A]. The O(2)⋯O(2) separation between non-coordinated picolinate oxygen atoms of adjacent polyhedra is 2.41 (1) A. The IR and Raman spectral results confirm the existence of neutral picolinic acid as well as the picolinate anion.

Synthesis and characterization of binuclear and polymeric five-coordinate copper(II) complexes derived from 3,3′,3″-triaminotripropylamine (trpn): Crystal structure of [Cu(trpn)(N3)]ClO4 (I) and [Cu2(trpn)(tren)(NO2)(H2O)](ClO4)3 (II)

Abstract The synthesis and characterization of five-coordinate copper(II) complexes derived from 3,3′,3″-triaminotripropylamine (trpn) are described. The X-ray diffraction studies have established the structures [Cu(trpn)(N3)]ClO4 (I) and [Cu2(trpn)(tren)(NO2)(H2O)](ClO4)3 (II). Compound (I) consists of a polymeric cation chain and ClO4− counter ions. The coordination geometry of the Cu(II) centers may be described as distorted square pyramidal (SP) with the azido group at the apical site and three nitrogen donors of the trpn molecule occupy the basal sites. The CuN5 chromophore is completed by a bridging aminopropyl group of neighboring trpn ligand. Compound (II) is a dinuclear complex cation with two different cation geometries in the unit cell. The geometry of the Cu(II) binding tren ligand is close to trigonal bipyramidal (TBP), with the basal and apical sites are occupied by the four nitrogen atoms of the tren ligand. The fifth coordination site is bridged to one of the aminopropyl arms of the trpn ligand. The geometry of the second Cu(II) center may be described as close to distorted SP, where the trpn ligand is binding the Cu(II) ion via the two primary aminopropyl groups and the tertiary nitrogen. The remaining two sites are occupied by oxygen atoms of a water molecule and nitrite ion. The intramolecular Cu…Cu distance in I and II ranges from 7.55 A to 7.94 A. The visible spectra of the complexes in DMSO are consistent with the X-ray results found for I and II and show a greater tendency toward SP geometry.

Preparation and structural characterization of catena-μ(1,3)-azido-μ(O,N-picolinato)-aquamanganese(II), Mn(NC5H4CO2)(N3)(H2O)

Abstract A mixed ligand complex of manganese(II) azide with picolinic acid, namely catena-μ(1,3)-azido-μ(O,N-picolinato)aquamanganese(II), was synthesized and characterized by X-ray crystallography. The coordination environment of the manganese(II) atom is a distorted octahedron. Each metal atom, which links a water molecule [MnO(1) = 2.218(3) A], is chelated by a picolinato anion [via its ring nitrogen atom, MnN = 2.278(3) A, and a carboxylato oxygen atom, MnO(2) = 2.167(2) A]. The chelating carboxylate O(2) atom is further bridging another manganese atom giving rise to a centrosymmetric dimeric Mn2O2 [MnO(2a) = 2.243(2) A]. These dimeric units are connected to μ(1,3) bridging azido ligands [MnN = 2.167(3) and 2.219(3) A] to form a two dimensional layer structure along the ab plane. Each water molecule forms two OH···O hydrogen bonds with the non-chelating carboxylate oxygen atoms of two adjacent picolinato groups. The IR and Raman spectra are also reported and correlated with the structure of the complex. The vibrational bands of diagnostic value are compared to the values of the carboxylic acid and the free anion.

Topological ferrimagnetic behavior of one new chain with the new AF/F/F'/F'/F alternating sequence

An azido-bridged chain with formula [Mn(Menic)(N3)2]n, where Menic is methylnicotinate, was prepared and studied from the magnetic point-of-view. This compound crystallizes in the monoclinic system, space group P21/a, with a = 15.556(2), b = 16.831(2), c = 17.595(2) A, β = 110.80(1)° and Z = 10. The structure consist of a one-dimensional system in which each manganese atom is bridged by two azido ligands in a trans arrangement. Along the chain there are four double end-on azido bridges followed by one double end-to-end azido bridge. This unusual kind of alternation leads to a new one-dimensional magnetic behavior, which has been studied by means of susceptibility and single crystal ESR measurements. The magnetic response has been reproduced by Monte Carlo simulations and exact laws following the classical approach. The characteristic signature of the magnetic behavior has allowed us to determine the three different magnetic coupling constants present in this system. These results have been analyzed in the framework of a theoretical and experimental magneto-structural correlation.