Laila H. El-Sayed

Coordination compounds of hydrazine derivatives with transition metals—VI: The reaction of aroylhydrazines with nickel(II), cobalt(II) and copper(II) salts

Abstract The reaction of aroylhydrazines with nickel(II), cobalt(II) and copper(II) ions were investigated. Both bis and tris nickel(II) and cobalt(II) chelates were isolated; magnetic and spectral measurements revealed their octahedral structure. With copper(II) nitrate and sulphate, aroylhydrazines gave only bis complexes. However, with copper(II) chloride, both mono and bis chelates were obtained at low temperature while at high temperature, oxidation-reduction reactions occurred with the formation of complexes with mixed oxidation states of copper. In all the metal chelates prepared in this work, the aroylhydrazine molecule acted as a neutral bidentate ligand, coordinating via the carbonyl oxygen and the amino-nitrogen.

Development of immunization trials against Klebsiella pneumoniae.

Klebsiella pneumoniae is the most common cause of nosocomial respiratory tract and premature intensive care infections, and the second most frequent cause of Gram-negative bacteraemia and urinary tract infections. Drug resistant isolates remain an important hospital-acquired bacterial pathogen, add significantly to hospital stays, and are especially problematic in high impact medical areas such as intensive care units. Many investigations worldwide proved the increasing resistance of such pathogen, resulting in an average rate of 1.63 outbreak every year. A variety of preventive measures were applied to reduce such incidences. Immunotherapy and passive immunization researches as well found their way to the treatment of Klebsiella. During the last 40 years, many trials for constructing effective vaccines were followed. This up-to-date review classifies such trials and documents them in a progressive way. A following comment discusses each group benefits and defects.

Synthesis, characterization and magnetochemical studies of dicopper(II) complexes derived from bis(N-salicylidene)dicarboxylic acid dihydrazides

Two series of dicopper(II) complexes derived from bis(N-salicylidine)dicarboxylic acid dihydrazides (H4L n ) of general formula [Cu2(L n )·xH2O]·yH2O and [Cu2(H2L n )Cl2·xH2O]·yH2O have been synthesized and characterized, where n refers to the number of carbon atoms in the aliphatic spacer between the two N-salicylideneacylhydrazine units. Magnetic susceptibility measurements for neutral dicopper(II) complexes [Cu2(L n )·xH2O]·yH2O indicate significant antiferromagnetic coupling between copper(II) centers. The −2J values obtained from the Bleany–Bowers equation are within the range 121–223 cm−1, suggesting association of the coordinated copper(II) units Cu(ONO) via phenoxy bridges. This leads to a polynuclear structure in which the dimeric units are connected with the aliphatic spacer. From the best-fit values of the mole fraction of paramagnetic uncoupled copper(II) centers (ρ), the degree of association in these polynuclear copper(II) complexes has been estimated. The chloro dicopper(II) complexes [Cu2(H2L n )Cl2·xH2O]·yH2O with n = 0, 2 and 3 also show strong antiferromagnetic exchange coupling (−2J = 215–423 cm−1), suggesting a polynuclear structure in which the copper(II) is in a distorted square-pyramidal environment, bound in the equatorial plane with a monoanionic ONO tridentate acylhydrazone unit and the μ-phenoxy oxygen and the axial site occupied by a chloride. The dicopper(II) complexes with n = 1 and 4 show weak antiferromagnetic exchange coupling (−2J = 16–20 cm−1). In these complexes the chloride ion may occupy the fourth equatorial site while the μ-phenoxy is in the apical position.

Coordination compounds of hydrazine derivatives with transition metals—XV Electronic and 1H NMR spectra of some diamagnetic metal(II) chelates with bidentate Schiff bases derived from hydrazine-S-methyl-dithiocarboxylate and thiosemicarbazide

Abstract A series of diamagnetic bis ligand Zn(II), Cd(II), Hg(II), Ni(II) and Pd(II) chelates with some Schiff bases derived from hydrazine-S-methyldithiocarboxylate(III) and the corresponding acid amide(IV) were prepared and characterized. The H NMR spectral studies showed that the Schiff base ligands derived from aromatic aldehydes as well as their metal(II) chelates exist only in one configuration with the aldehydic hydrogen syn to the NN bond. The ligand (III) derived from asymmetric ketones exist as a mixture of syn and anti configurations. The H NMR spectra of the corresponding Zn(II), Cd(II), Hg(II) and Ni(II) chelates indicate the presence of a trans isomer in syn and anti configurations. The spectra of Pd(II) chelates with ligand (III) show the possible existence of both cis and trans isomers in both syn and anti configurations. Besides, the syn and anti configurations, the Zn(II) and Ni(II) chelates with (III, R1 = CH3, R2 = CH2C6H5) appear to exist in different conformations. Ni(II) chelates derived from acetophenone derivatives exist predominantly in cis-syn configuration.

Development of immunization trials against Pasteurella multocida

Pasteurellosis is one of the most important respiratory diseases facing economically valuable farm animals such as poultry, rabbit, cattle, goats and pigs. It causes severe economic loss due to its symptoms that range from primary local infection to fatal septicemia. Pasteurella multocida is the responsible pathogen for this contagious disease. Chemotherapeutic treatment of Pasteurella is expensive, lengthy, and ineffective due to the increasing antibiotics resistance of the bacterium, as well as its toxicity to human consumers. Though, biosecurity measures played a role in diminishing the spread of the pathogen, the immunization methods were always the most potent preventive measures. Since the early 1950s, several trials for constructing and formulating effective vaccines were followed. This up-to-date review classifies and documents such trials. A section is devoted to discussing each group benefits and defects.

Coordination compounds of hydrazine derivatives with transition metals—VII: Metal(II) complexes with hydrazine s-methyl dithiocarboxylate Schiff bases and their pyridine adducts

Abstract Metal(II) chelates of general formula M ( R 1 R 2 CN−NCSSCH 3 ) 2 ( M Ni( II ), Co(II) and Cu(II); R 1 = R 2 = CH 3 ; R 1 , R 2 = C 5 H 10 − and R 1 = CH 3 , R 2 = C 6 H 5 ) were prepared and investigated. Magnetic and spectral data indicated square planar Ni(II) complexes while Co(II) afforded tetrahedral complexes. All the Cu(II) chelates probably possessed a dimeric pentacoordinate geometry. The reaction of pyridine with the bis metal (II) complexes were discussed. Monopyridinate adducts were isolated with the bis (N-isopropylidene hydrazine-S-methyldithiocarboxylate) cobalt (II) and nickel (II) chelates.

Coordination compounds of hydrazine derivatives with transition metals. V. Square planar nickel(II) complexes with hydrazine-S-methyl dithiocarboxylate schiff bases

Abstract Schiff bases derived from the condensation of hydrazine-S-methyl dithiocarboxylate with substituted benzaldehyde and heterocyclic aldehydes were prepared. Their reactions with Ni II chloride and acetate were investigated. Magnetic and spectral data have shown that square planar Ni II complexes resulted from all the Schiff bases. Bis neutral complexes were obtained with the Schiff bases acting as monobasic bidentate ligands. In addition, 1:1 complexes were isolated with salicylaldehyde and pyridine-2-carbaldehyde derivatives where the Schiff bases functioned as dibasic tridentate and monobasic tridentate ligands respectively. The interaction of the square planar Ni II complexes with pyridine was also investigated.

Coordination compounds of hydrazine derivatives with transition metals. Part 20. Nickel(II) chelates witho-hydroxy ando-methoxy-benzaldehyde aroylhydrazones. An example of coordination isomerism

SummaryA series of monoligand nickel(II) chelates Ni(SalC6H4X) · 3 H2O containing salicylaldehyde aroylhydrazones H2SalC6H4X were isolated and characterized. The correspondingo-methoxyhenzaldcliyde aroylhydrazones (HMeOBhC6H4X) react with nickel(II) acetate to give isomeric red and green chelates of stoichiometry M(MeOBhC6H4X)2. The red isomers were assumed to possess a square planar arrangement with the hydrazone molecule acting, as a mononegative bidentate ligand, whereas an octahedral structure was assigned to the green isomer with the hydrazone molecule acting as mononegative tridentale ligand. The pyridine and 1,10-phenanthrolinc adducts of the complexes were characterizcd.

Coordination compounds of hydrazine derivatices with transition metals—XIX: Redox reactions of Cu(II) salts with thiosemicarbazide and hydrazine-S-methyl dithiocarboxylate schiff bases

Abstract Schiff base ligands derived from hydrazine-S-methyl dithiocarboxylate (R1R2CNNH·CSSMe) can react with Cu(II) salts to give either Cu(I) or Cu(II) chelates depending on the anion of the salt used, the nature of R1 and R2 in the ligand molecule and the temperature of the reaction medium. A tentative mechanism for the reduction of Cu(II) salts by these ligands was proposed. From the magnetic measurements, electronic and ESR spectral data the structure of the Cu(II) chelates was assigned.

Coordination compounds of hydrazine derivatives with transition metals. Part 24. Coordination chemistry of hydrazine-S-methyl carbodithioate schiff bases derived from β-dicarbonyl compounds

SummaryThe reactions of β-diketones and β-ketoaldehydes with hydrazine-S-methyl carbodithioate, hydth, have been studied in the absence and presence of metal(II) ions. A series of dimeric monoligand chelates [Ni(β-dikhydth-2H)]2 have been isolated. The reaction of these chelates with monodentate Lewis bases yields square planar [Ni(β-dikhydth2H)B] chelates. Bisligand chelates of benzoylacetone monohydrazones [M(Bzachydth-H)2] (M=Cu or Zn) have been also synthesized, as have a series of NiII and ZnII chelates of β-diketone bishydrazones of the type [M(β-dik(hydth)2-2H)].