Transition metal complexes with Girard reagents and their hydrazones

This is the first review dealing with the coordination chemistry of metal complexes with Girard's reagents and their hydrazones. The short introduction points out to chemical properties and significance of these organic compounds. The next section briefly describes synthetic methods for preparing complexes with Girard's reagents, as well as modes of coordination of these ligands. The last two extensive sections review the preparation, stereochemistry and structural characteristics of metal complexes with Girard's hydrazones, including some newer non-hydrazonic derivatives of Girard's reagents, also.[Acknowledgments. Projekat Ministarstva nauke Republike Srbije, br. 172014

Bis{N,N,N-trimethyl-2-oxo-2-[2-(2,3,4- trihydroxy­benzyl­idene)hydrazin­yl]ethanaminium} tetra­chlorido­zincate(II) methanol solvate1

The asymmetric unit of the title compound, (C12H18N3O4)2[ZnCl4]·CH3OH, consists of two Girard reagent-based cations, a tetra­chlorido­zincate anion and a mol­ecule of methanol as solvate. These components are inter­connected in the crystal structure by an extensive network of O—H⋯O, N—H⋯O, C—H⋯O, O—H⋯N, O—H⋯Cl, N—H⋯Cl and C—H⋯Cl hydrogen bonds. The shortest inter­molecular inter­action is realized between the cation and anion [H⋯Cl = 2.29 (5) Å; O—H⋯Cl = 167 (3)°]. C—H⋯O inter­actions also play a important role in the inter­connection of the cations

Transition metal complexes with thiosemicarbazide-based ligands. Part 60. Reactions of copper(II) bromide with pyridoxal S-methylisothiosemicarbazone (PLITSC). Crystal structure of [Cu(PLITSC−H)H2O]Br•H2O

The synthesis and structural characterization of a square-planar copper(II) complex with pyridoxal S-methylisothiosemicarbazone (PLITSC) of the formula [Cu(PLITSC−H)H2O]Br•H2O (1) as the first Cu(II) complex with monoanionic form of this ligand were described. Complex 1 together with two previously synthesized complexes [Cu(PLITSC)Br2] (2) and [Cu(PLITSC)Br(MeOH)]Br (3) were characterized by elemental analysis, IR and electronic spectra and also by the methods of thermal analysis, conductometry and magnetochemistry. [Projekat Pokrajisnkog sekretarijata za nauku i tehnoloski razvoj Vojvodine i Ministarstva nauke Republike Srbije, br. 172014

Synthesis and structural characterization of Cd(II) complexes with 2-acetylpyridine-aminoguanidine - a novel coordination mode

The structures of the first two complexes with bidentate coordination of aminoguanidine Schiff base, i.e., 2-acetylpyridine-aminoguanidine (L), are reported. The complex of the formula [Cd2Cl6(HL)2] (1) was obtained in the reaction of warm aqueous solutions of chloride salts of Cd(II), Zn(II) and the ligand, while the reaction of cadmium bromide and the ligand in the presence of deprotonating agent as well as ammonium thiocyanate resulted in the formation of the complex in which Schiff base has both the role of the ligand and the counterion, viz., [HL][Cd(HL)(NCS)2XY]·H2O (2), where X is Cl- or Br-, and Y Br- or SCN-. The complexes were characterized by IR spectroscopy, elemental analysis, conductometric measurements and single crystal X-ray diffraction. The unusual bidentate coordination of the Schiff base lead to significant changes in the geometry of this molecule (from almost planar in free form and as a tridentate ligand to twisted as a bidentate ligand). Besides, in complex 1 relatively rare bridging coordination of Cl- in octahedral Cd(II) is found, while the crystal structure of complex 2 exhibits substitutional disorder, and contains four different anions: [Cd(HL)(NCS)2Br(SCN)]- (ca. 61 %), [Cd(HL)(NCS)2Cl(SCN)]- (ca. 35 %), [Cd(HL)(NCS)2Br2]- (ca. 3 %) and [Cd(HL)(NCS)2ClBr]- (ca. 1 %)

Syntheses and characterization of 2-acetylpyridine-aminoguanidine and its copper(II) complexes: Crystallographic and antimicrobial study

The syntheses, physico-chemical and microbiological properties of the ligand, 2-acetylpyridine-aminoguanidine dihydrogensulfate monohydrate and its five complexes with Cu(II) are described. The compounds were characterized by single crystal X-ray crystallography. Common fragments encountered in some of the structures were compared by r.m.s. overlay calculations as well as half-normal probability plots. In these complexes the chelate ligand is coordinated in its neutral form in a tridentate N-3-coordination mode, via pyridine, azomethine and imino nitrogen atoms of the aminoguanidine fragment. In these complexes the Cu(II) ion is situated in moderately or severely distorted square-pyramidal surroundings. The antimicrobial activity of the ligand and the complexes were examined against 6 selected bacterial and 3 fungal strains.This is peer-reviewed version of the following article: Vojinović-Ješić, L. S.; Radanović, M. M.; Rodić, M. V.; Živković-Radovanović, V.; Jovanović, L. S.; Leovac, V. M. Syntheses and Characterization of 2-Acetylpyridine-Aminoguanidine and Its Copper(II) Complexes: Crystallographic and Antimicrobial Study. Polyhedron 2016, 117, 526–534. [https://doi.org/10.1016/j.poly.2016.06.032]Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3583

First cobalt complexes with methyl pyruvate semi/thiosemicarbazone - synthesis, physico-chemical and structural characterization

In the reaction of acetone solutions of CoX2∙nH2O (X = Cl, Br) with methyl pyruvate semi/thiosemicarbazone (Hmps, Hmpt) the first Co(II) complexes with these ligands, i.e., [Co(Hmps)(H2O)X2] (X = Cl (1), Br (2)), [Co(Hmpt)2][CoCl4]∙2H2О (3) and [Co(Hmpt)2]Br2∙Me2CO (4) were obtained. Complexes 1 and 2 represent the first examples of metal complexes of Hmps. All the obtained compounds were characterized by elemental analysis, conductometry, magnetic measurements, and IR spectra, and for complexes 2–4, single crystal X-ray diffraction analysis was also performed. The effective magnetic moments were close to the upper limit (5 μB) for complexes 1 and 2, and close to the lower limit (4.4 μB) for complexes 3 and 4, and as such are characteristic for high-spin Co(II) complexes. Structural analysis showed that both ligands coordinate in a neutral form in a tridentate manner, via the ester oxygen, imine nitrogen and the oxygen atom of the ureido (Hmps), or the sulfur atom of the thioureido group (Hmpt). The central metal atoms are situated in a deformed octahedral coordination environment. Complex 2 has cis-Br configuration, while complexes 3 and 4 have mer-configuration

Amino­(5-{2-[amino­(iminio)meth­yl]hydrazin-1-yl}-3,5-dimethyl-4,5-dihydro-1H-pyrazol-1-yl)methaniminium dinitrate

The reaction of aqueous solutions of amino­guanidine hydrogennitrate and acetyl­acetone produces the title pyrazole salt, C7H18N8 2+·2NO3 −. The crystal structure is stabilized by a complex N—H⋯O hydrogen-bonding network. The difference in the engagement of the two nitrate anions in hydrogen bonding is reflected in the variation of the corresponding N—O bond lengths

Transition metal complexes with Girard reagent-based ligands. Part IV. Synthesis and characterization of pyridoxilidene Girard-T hydrazone complexes. Crystal structure of the copper(II) complex

The monoligand complexes of the formula M(HPLGT)(NCS)(2) (M = Cu(II), Zn(II)) in which the ligand tridentate ONO pyridoxilidene Girard-T hydrazone, [H(3)PLGT]Cl(2) center dot 2H(2)O, was coordinated in neutral doubly deprotonated form were synthesized. Also, the first complexes with the ligand coordinated in triply deprotonated monoanionic form of the formula [Cu(PLGT)N(3)] and [Co(PLGT)(NO(2))(2)NH(3)] center dot 3H(2)O are reported. The single crystal X-ray analysis of [Cu(HPLGT)(NCS)(2)] showed that Cu(II) is placed in a square-pyramidal surrounding consisting of one tridentate Schiff base and one NCS group in the basal plane and the other NCS group in the apical position. Intermolecular hydrogen bonds leading to centrosymmetrical dimerization of these complexes were discussed. In the reaction of Girard-T and Hacac in the presence of CuCl(2), a mixture of single crystal complexes of the composition [Cu(3,5-Me(2)pz)(2)Cl(2)](2) and [Cu(acac)(2)] center dot 2[Cu(3,5-Me(2)pz)(2)Cl(2)] was obtained and X-ray analysis of the latter one was reported

Computational Identification and Characterization of a Promiscuous T-Cell Epitope on the Extracellular Protein 85B of Mycobacterium spp. for Peptide-Based Subunit Vaccine Design

Tuberculosis (TB) is a reemerging disease that remains as a leading cause of morbidity and mortality in humans. To identify and characterize a T-cell epitope suitable for vaccine design, we have utilized the Vaxign server to assess all antigenic proteins of Mycobacterium spp. recorded to date in the Protegen database. We found that the extracellular protein 85B displayed the most robust antigenicity among the proteins identified. Computational tools for identifying T-cell epitopes predicted an epitope, 181-QQFIYAGSLSALLDP-195, that could bind to at least 13 major histocompatibility complexes, revealing the promiscuous nature of the epitope. Molecular docking simulation demonstrated that the epitope could bind to the binding groove of MHC II and MHC I molecules by several hydrogen bonds. Molecular docking analysis further revealed that the epitope had a distinctive binding pattern to all DRB1 and A and B series of MHC molecules and presented almost no polymorphism in its binding site. Moreover, using “Allele Frequency Database,” we checked the frequency of HLA alleles in the worldwide population and found a higher frequency of both class I and II HLA alleles in individuals living in TB-endemic regions. Our results indicate that the identified peptide might be a universal candidate to produce an efficient epitope-based vaccine for TB