Imine Nitrogen Atoms Research Articles

N'-isonicotinoylpicolinohydrazonamide: Synthesis, crystal structure, DFT and ADMET studies, and in silico inhibition properties toward a series of COVID-19 proteins

In this work, synthesis as well as detailed structural and computational analyses of the novel isoniazid derivative, namely N'-isonicotinoylpicolinohydrazonamide (1), are reported. The obtained compound was examined by microanalysis, IR, 1H NMR spectroscopy and single crystal X-ray diffraction. The crystal packing was studied by the Hirshfeld surface analysis. Molecules in the crystal structure of 1 are linked through N–H⋯O and N–H⋯N hydrogen bonds, and π⋯π interactions, yielding a 1D supramolecular chain. According to the Hirshfeld surface analysis, crystal packing of 1 is primarily dictated by H⋯H, H⋯C, H⋯N and H⋯O contacts, of which the latter three contacts are highly favoured. The crystal packing is further characterized by highly favoured C⋯C contacts. Compound 1 was also studied using DFT in gas phase, which revealed its pronounced electrophilic features. The most electron-rich (nucleophilic) sites were revealed for the carbonyl oxygen atom, and 4-pyridyl and imine nitrogen atoms, while the most electron-deficient (electrophilic) sites were found for the NH and NH2 hydrogen atoms. Compound 1 was predicted to belong to a fourth class of toxicity and exhibits negative blood–brain barrier penetration and positive gastrointestinal absorption property. In silico molecular docking was applied to probe 1 as a potential inhibitor of a series of the SARS-CoV-2 proteins and it was found that 1 is potentially active against all the applied proteins with the best activity against Nonstructural protein 3 (Nsp3_range 207–379-MES). It was also established that the best docking scores for 1 were found for the cavities, where initial ligands were located, except for the Papain-like protease (PLpro). The best binding affinity of the latter protein with 1 was revealed for the other cavity with about 0.8 kcal/mol being more efficient. Molecular dynamics simulations were also applied to evaluate the stability of complexes PLproI–1, PLproII–1 and Nsp_range 207–379-MES–1. Complex PLproI–1 was found to be highly unstable, while complexes PLproII–1 and Nsp_range 207–379-MES–1 are stable.

Mass-spectra of new heterocycles: XXIV. Electron impact and chemical ionization study of <i>N</i>-[3-alkoxyand 3-(1<i>H</i>-pyrrol-1-yl)-2-thienyl]imidothiocarbamates

The behavior of a wide range of previously unknown N -(2-thienyl)imidothiocarbamates synthesized in a single preparative step from heterosubstituted allenes (methoxy-, 1-ethoxyethoxy- and 1 H -pyrrol-1-ylallenes) and aliphatic, cycloaliphatic, and aromatic isothiocyanates was studied under conditions of electron (70 eV) and chemical (reagent gas - methane) ionization. Under the electron impact, the studied compounds form an unstable molecular ion, the main direction of fragmentation of which is associated with the breaking of the C-N bond in the imidoformamide fragment with charge localization at the imine nitrogen atom. A similar decay channel of a molecular ion is also observed in the chemical ionization mass spectra of the studied compounds. In this case, characteristic, but low-intensity ions in the electron ionization spectra of N -(3-methoxy-2-thienyl)imidothiocarbamates become dominant in the chemical ionization spectra. In the chemical ionization spectra of N -[3-(1 H -pyrrol-1-yl)-2-thienyl]imidothiocarbamates, the maximum intensity peak belongs to the [ M - SMe]+ ion. For N -[3-(1-ethoxyethoxy)-2-thienyl]imidothiocarbamate, the peak of the ion formed upon successive elimination of ethoxyethene and methanethiol molecules from the [ M + H]+ ion has the maximum intensity.

Regioselective Cycloaddition of Nitrile Imines to 5-Methylidene-3-phenyl-hydantoin: Synthesis and DFT Calculations.

Nitrile imine cycloaddition to hydantoins containing an exocyclic C=C double bond has been previously described in a very limited number of examples. In this work, regioselective synthesis of spiro-pyrazoline-imidazolidine-2,4-diones based on a 1,3-dipolar cycloaddition reaction of nitrile imines to 5-methylidene-3-phenyl-hydantoin have been proposed. It was found that, regardless of the nature of the aryl substituents at the terminal C and N atoms of the C-N-N fragment of nitrile imine (electron donor or electron acceptor), cycloaddition to the 5-methylidenhydantoin exocyclic C=C bond proceeds regioselectively, and the terminal nitrogen atom of the nitrile imine connects to the more sterically hindered carbon atom of the double bond, which leads to the formation of a 5-disubstituted pyrazoline ring. The observed cycloaddition regioselectivity was rationalized using DFT calculations of frontier molecular orbital interactions, global CDFT reactivity indices, and minimum energy paths.

An insight into the hydrogen bonding, halogen bonding and chalcogen bonding interactions in manganese(iii) complexes with N2O2donor salicylidine Schiff base ligands.

Four manganese(iii) complexes, [MnL1(H2O)2]ClO4·H2O (1), [MnL2(H2O)2]ClO4 (2), [MnL3(DMSO)(H2O)]ClO4 (3) and [MnL4(DMSO)(H2O)]ClO4 (4), where H2L1 = N,N'-bis(5-bromosalicylidene)-1,3-diaminopropane, H2L2 = 2,2-dimethyl-N,N-bis(3-methyloxysalicylidene)-1,3-diaminopropane, H2L3 = N,N'-bis(5-chlorosalicylidene)-2,2-dimethyl-1,3-diaminopropane and H2L4 = 2-hydroxy-N,N'-bis(3-ethyloxysalicylidene)-1,3-diaminopropane are tetradentate N2O2-donor ligands and DMSO = dimethyl sulfoxide, have been synthesized and characterised by elemental analysis, IR and UV-vis spectroscopy and single-crystal X-ray diffraction studies. All are monomeric complexes. Complex 1 crystallises in orthorhombic space group P212121, complex 3 crystallises in triclinic space group P-1, whereas complexes 2 and 4 crystallize in monoclinic space groups, C2/c and C2/m respectively. In all the complexes, manganese(iii) has a six-coordinated pseudo-octahedral geometry in which imine nitrogen atoms and phenolate oxygen atoms of the deprotonated di-Schiff base constitute the equatorial plane. In complexes 1 and 2, water molecules are present in the fifth and sixth coordination sites in the axial positions while in complexes 3 and 4 they are occupied by one water and one DMSO. The coordinated water molecules initiate hydrogen-bonded networks in all complexes. DFT calculations have been carried out to analyze two aspects of these complexes viz. the formation of halogen (HaB) and chalcogen bonding (ChB) interactions in complexes 1 and 3 where the electron donor is the perchlorate anion and the acceptor either bromine or chlorine atoms for the HaBs and the sulfur atom of the coordinated DMSO for the ChB. In addition, other intermolecular effects are discussed in the solid state for complexes 1, 2 and 4, where the hydrogen atoms of the coordinated water molecules interact with the electron rich cavities formed by the phenolate and alkyloxy oxygen atoms of the Schiff-base ligand.

Electronic origins of the stereochemistry in β-lactam formed through the Staudinger reaction catalyzed by a nucleophile.

This paper evaluates the electronic effects of molecular substituents on the stereoselectivity of the umpolung Staudinger catalytic reaction. This is especially important because experimental studies on constructing the β-lactam ring, a core structure of most antibiotics, through catalyzed Staudinger reactions have been massively progressing over the last century. Yet, there is a necessity for an in-depth understanding of the reaction mechanisms to help chemists, working on the well-established discoveries, improve these to optimize the stereoselectivity and yield of synthetic methods. Access to practical and effective advancements in forming optically pure β-lactam is paramount in the field of medical chemistry. This paper specifically investigates how changing the N-protecting group in the imine fragment can switch the stereoselectivity of the PPY-catalyzed Staudinger reaction. To do so, we employed the density functional theory (DFT) for geometry optimization and electronic analysis at the B3LYP/6-31G(d) level of theory to examine and compare the role of N-tosyl (N-Ts) and N-triflyl (N-Tf) imine on the mechanism pathways, i.e., imine-first or ketene-first, and stereochemistry of the reaction, i.e., cis or trans β-lactam. Our results show that the reaction mechanism pathway cannot be simply switched from ketene-first to imine-first by changing the substituent on the imine nitrogen atom, which is contrary to the reported experimental results, and both imines go through the ketene-first mechanism with different stereochemistries, which is cis selective for imine-Ts and trans selective for imine-Tf. Based on electronic analyses, the reversal in diastereoselectivity in the N-triflyl imine system could be attributed to the charge transfers and electron-density distribution over the transition states. Therefore, the cis/trans selectivity of the PPY-catalyzed Staudinger reaction could be effectively controlled by the electronic characteristics of the molecular substituents in the reactants. A N-protecting group in imine with a more electron-withdrawing nature seems to accelerate the stereo-determining step, ring closure, and increase the stabilization charge transfers in the transition state, leading to a preference for trans β-lactam formation. It seems that using a N-substituent with a higher electron-withdrawing nature can initially activate the imine by the nucleophilic catalyst in competition with ketene, i.e., imine-first versus ketene-first. These results can provide an insight into select proper substituents for the fragments to synthesis β-lactam with a desired stereochemistry. Also, a comprehensive comparison was performed between calculations with and without dispersion.

Synthesis, Physico-chemical, Spectral And Molecular Docking studies of 4-[(E)benzylideneamino]-5-methyl-4H-1,2,4-triazole-3-thiol and Its Metal Complexes with Cu(II), Ni(II), Co(II) and Zn(II)

Heterocyclic compounds like Triazoles have great medicinal value. There metal complexes have also shown a vide range of biological activity. In the present research, a triazole derived ligand, 4-[(E)-benzylideneamino]-5methyl-4H-1,2,4-triazole-3-thiol and its metal complex with Cu(II), Ni(II), Co(II) and Zn(II) metal ions were prepared in solid state. The ligand and its metal complexes were characterized by elemental analysis and spectral techniques like IR spectra and UV-Visible spectra. The shift in the infrared spectral band indicates bonding of metal ion with ligand through deprotonated thiol group and imine ( C=N) Nitrogen atom. The ligand is bidentate. The IR spectral analysis also showed that a large amount of lattice water is present in Ni(II) and Co(II) complex. All the metal complexes and ligand are neutral species soluble in organic solvents like DMF and DMSO. UV-Visible spectra of Cu(II), Ni(II) and Co(II) complexes indicate that their geometry is distorted octahedral. The molecular docking of the synthesized compounds was performed using CB Dock 2 server against 1JIJ protein derived from Staphylococcus Aureus. The vina score obtained indicates that compounds inhibits the protein and are potentially anti-bacterial

Towards Efficient and Stable Donor-Acceptor Luminescent Radicals.

In contrast to closed-shell luminescent molecules, the electronic ground state and lowest excited state in organic luminescent radicals are both spin doublet, which results in spin-allowed radiative transitions. Most reported luminescent radicals with high photoluminescent quantum efficiency (PLQE) have a donor-acceptor (D-A•) chemical structure where an electron-donating group is covalently attached to an electron-withdrawing radical core (A•). Understanding the main factors that define the efficiency and stability of D-A• type luminescent radicals remains challenging. Here, wedesigned and synthesized a series of tri(2,4,6-trichlorophenyl)methyl (TTM) radical derivatives with donor substituents varying by their extent of conjugation and their number of imine-type nitrogen atoms. The experimental results suggest that the luminescence efficiency and stability of the radicals are proportional to the degree of conjugation but inversely proportional to the number of imine nitrogen atoms in the substituents. These experimental trends are very well reproduced by density functional theory calculations. The theoretical results indicate that both the luminescence efficiency and radical stability are related to the energy difference between the charge transfer (CT) and local-excitation (LE) states, which decreases as either the number of imine nitrogen atoms in the substituent increases or its conjugation length decreases.

Synthesis of Benzhydryl-Substituted Amines by Silanolate-Mediated Aldimine Arylation with Functionalized Aryl Nucleophiles Released from Diazene-Based Reagents.

A transition-metal-free protocol for the arylation of N-phenyl- and N-benzoyl-substituted, benzaldehyde-derived imine derivatives with functionalized aryl pronucleophiles is reported. The aryl nucleophiles are released from silicon-protected aryl-substituted diazenes by desilylation with potassium trimethylsilanolate concomitant with the loss of dinitrogen. A broad range of functional groups is tolerated in the aryl nucleophile but, depending upon their electronic effect, require specific groups at the imine nitrogen atom.

Surprising Solid-State ESIPT Emission from Apparently Ordinary Salicyliden Glycinates Schiff Bases

Excited-State Intramolecular Photon Transfer (ESIPT) is known for the geometry-related phenolic and imine groups. The Schiff bases formed upon condensation of salicyl aldehyde and glycine led to the formation of ESIPT models. A series of alkali metal salicyliden glycinates were analyzed by X-ray diffraction of their monocrystals and spectroscopy measurements. The X-ray analysis revealed varied hydration levels between the salts. They adapted trans geometry on the imine groups and mostly anticlinal conformation with the neighboring atoms, which is different from the other structurally-related compounds in literature. Fluorescence of these compounds was found for the crystalline forms only. Protonation of the imine nitrogen atom and further proton distribution was consistent with the ESIPT theory, which also explained the observed fluorescence with the highest Stokes shift of 10,181 cm-1 and 10.1% of fluorescence quantum yield for the sodium salt.

Trivalent Cobalt Complexes with NNS Tridentate Thiosemicarbazones: Preparation, Structural Study and Investigation of Antibacterial Activity and Cytotoxicity against Human Breast Cancer Cells

New complexes of trivalent cobalt with substituted thiosemicarbazone ligands having an NNS donor system {HL1 = 4-(4-nitrophenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were synthesized via the in situ oxidation of divalent cobalt chloride accompanying its addition to the ligands. The complexes C1 and C2 were characterized via elemental (CHNS) analysis and 1H NMR, FT-IR and UV-Vis. spectroscopic data. Further, conductometric studies on the DMF solutions of the complexes indicated their 1:1 nature, and their diamagnetism revealed the low-spin trivalent oxidation state of the cobalt in the complexes. The X-ray diffraction analysis of complex C1 indicated that it crystallizes in the triclinic space group P-1. The metal exhibits an octahedral environment built by two anionic ligands bound via pyridine nitrogen, imine nitrogen and thiol sulfur atoms. The complex is counterbalanced by a chloride ion. In addition, two lattice water molecules were detected in the asymmetric unit of the unit cell. The ligand HL2 (20 mg/mL in DMSO) displayed inhibition zones of 10 mm against both S. aureus and E. coli, and the same concentration of the respective complex raised this activity to 15 and 12 mm against these bacterial strains, respectively. As a comparison, ampicillin inhibited these bacterial strains by 21 and 25 mm, respectively. Screening assay by HL1 on four human cancer cells revealed the most enhanced activity against the breast MCF-7 cells. The induced growth inhibitions in the MCF-7 cells by all compounds (0–100 μg/mL) have been detected. The ligands {HL1 and HL2} and complex C2 gave inhibitions with IC50 values of 52.4, 145.4 and 49.9 μM, respectively. These results are more meaningful in comparison with similar cobalt complexes, but less efficient compared with the inhibition with IC50 of 9.66 μM afforded by doxorubicin. In addition, doxorubicin, HL1 and HL2 induced cytotoxicity towards healthy BHK cells with IC50 values of 36.42, 54.8 and 110.6 μM, but surviving fractions of 66.1% and 62.7% of these cells were detected corresponding to a concentration of 100 μg/mL of the complexes (136.8 μM of C1 and 131.4 μM of C2).

Ni(II), Zn(II), and Fe(III) complexes derived from novel unsymmetrical salen-type ligands: preparation, characterization and some properties

By using a half-salen ligand (HL) and substituted salicylaldehydes, new unsymmetrical salen-type ligands (H2L1, H2L2, and H2L3) and their Ni(II), Zn(II) and Fe(III) complexes were synthesized. The compounds were characterized based on elemental analysis, IR, 1H NMR, X-ray diffraction (for HL), spectroscopy, mass spectrometry, magnetic moment, molar conductance measurements, and thermal analysis (TGA). The unsymmetrical salen ligands, during complexation, are attached to the metal by two imine nitrogen atoms and two phenolic oxygen atoms in all complexes; in the Fe(III) complexes, the fifth coordination is completed by chloride. Square planar geometry or distorted square planar geometry for [NiL1-3], [ZnL1-3], and square pyramidal geometry for [FeL1-3Cl] are proposed. Conductance measurements suggest non-electrolytic nature of the metal complexes. Thermogravimetric analysis showed that the complexes exhibit higher stability than the ligands. The electrochemical properties of the compounds were studied by cyclic voltammetry. HOMO-LUMO energy levels and electrochemical band gaps (E′ g) were calculated. The solid state electrical conductivity of the iodine-doped compounds was measured and their semiconductor properties were determined. In addition, fluorescence properties of ligands and Zn(II) complexes were investigated.

Crystal structure of 1H-imidazole-1-methanol.

The synthesis and the crystal structure of 1H-imidazole-1-methanol, C4H6N2O, are described. This compound comprises an imidazole ring with a methanol group attached at the 1-position affording an imine nitro-gen atom able to receive a hydrogen bond and an alcohol group able to donate to a hydrogen bond. This imidazole methanol crystallizes with monoclinic (P21/n) symmetry with three symmetry-unique mol-ecules. These three mol-ecules are connected via O-H⋯N hydrogen bonding in a head-to-tail configuration to form independent three-membered macrocycles.

X-ray structural determination and comparison of Bis-imine Schiff bases with trans- and cis-1,2-cyclohexanediamine backbones

Analysis of the X-ray crystal structures of diimines cis-N,N’-bis(pyridine-2-ylmethylene)-1,2-cyclohexanediamine, known compound trans-N,N’-bis(pyridine-2-ylmethylene)-1,2-cyclohexanediamine, and racemic trans-N,N’-bis(phenylmethylene)-1,2-cyclohexanediamine reveals that the pyridyl diimines have greater imine C = N to 2-pyridine ring coplanarity than those found in the phenyl-substitued diimine. For the phenyl diimine, the lack of planarity and loss of conjugation is attributed to N = CH to ortho hydrogen steric repulsion that is relieved in the pyridyl diimines. In the phenyl diimine the closest intramolecular contact is between the N = CH hydrogen atom and an ortho hydrogen on the phenyl ring. The cis- and trans- pyridyl diimine molecules pack together via slightly different types of weak interactions. For the cis complex, the shortest interaction involves the nitrogen atom of the imine and a cyclohexyl hydrogen atom on an adjacent molecule. A ring CH to pyridine centroid interaction leads to the formation of tight dimers in the cis- diimine. For the trans-diimine the shortest interaction also involves the imine nitrogen atom, but with an interaction with a pyridyl hydrogen atom and it does not form dimers. The predominant packing interactions in trans-2 are due to ring stacking which gives rise to a 2D-layered structure.

Catalyst‐Free Synthesis of Diastereomerically Pure 3‐Cyanoazetidin‐2‐ones via Thermally Promoted Tandem Wolff Rearrangement–Staudinger [2+2] Cycloaddition

AbstractThermally promoted tandem Wolff rearrangement – Staudinger [2+2] cycloaddition of α‐cyano‐α‐diazo ketones and imines afforded 3‐cyano‐β‐lactams in good to excellent yields as one diastereomer. The process represents the first example of generating cyanoketenes via the Wolff rearrangement of diazo compounds. The reaction is virtually insensitive to the substitution pattern in both reaction partners. It afforded high product yields even for imines bearing bulky tertiary alkyl substituents at the imine's nitrogen atom, which is indicative of the reaction proceeding predominantly as the concerted [2+2] cycloaddition rather than stepwise N‐acylation – ring closure process. Examples of reductive manipulation of the resulting 3‐cyano‐β‐lactams are provided opening an entry into 3‐aminomethyl 2‐azetidinones and azetidines.

Unexpected synthesis of benzimidazole from Schiff base mediated by lanthanide chloride and citotoxic activities

Schiff bases and benzimidazoles compounds exhibit an extensive range of therapeutic applications, such as anticancer agents. The present study shows the synthesis of the 2-(4-methoxyphenyl)-1H-benzimidazole hydrochloride (BenzHCl) from N,N’-bis-(4-methoxybenzylidene)-benzene-1,2-diamine (Anisalophen) mediated by chloride lanthanide (Gd3+, Tb3+, or Eu3+). The mechanism of the reaction is proposed from different synthetic strategies. BenzHCl crystallizes in the monoclinic system, space group P21 and shows the iminic nitrogen atom protonated, which is stabilized by the chlorine ion. BenzHCl and Anisalophen were characterized, and their thermal stabilities were analyzed by TG/DTA techniques. Anisalophen and BenzHCl showed higher cytotoxic activity against human breast cancer cells (MCF-7 and MDA-MB-231) when compared to human fibroblast cells.

Structural investigations, Hirsfeld surface analyses, and molecular docking studies of a phenoxo-bridged binuclear Zinc(II) complex

A novel phenoxo-bridged zinc complex, [Zn2(L)µ(O-O)2H2OCl2] [L= deprotonated salen ligand, 2,2′-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azaneylylidene))bis(methaneylylidene))diphenol), was reported. The title complex was characterized by elemental analyses, single crystal X-ray crystallography, spectroscopic studies, and thermogravimetric analysis. The X-ray structure analysis reveals the coordination of Zn1 atom to two imine nitrogen atoms, two phenolic oxygen atoms, and the oxygen atom of aqua ligand, giving it a distorted square pyramidal geometry, whereas the Zn2 atom is bonded to the same phenoxide anions, and two chloride ions, resulting in a distorted tetrahedral geometry. In addition, TD-DFT and NBO analyses were investigated to obtain bonding information insights into the structure. Furthermore, Hirshfeld surface analysis was used to determine various intermolecular interactions in the complex. Furthermore, a docking analysis was performed on the B-DNA [sequence d (CGCGAATTCGCG)2dodecamer] (PDB ID:1BNA) using the AutoDockvina (scripps) software package. The fluorescence property of the title complex was also carried out, and revealed it to be excellent photoluminescent material.

Structural characterization of a square planar Ni(II) complex and its application as a catalyst for the transfer hydrogenation of ketones

A new 2-hydroxy-1-naphthaldehyde Schiff base derived nickel(II) complex (4) was synthesized and fully characterized. Analysis of the structure of 4 by single-crystal X-ray diffraction shows two chelating Schiff base ligands bound to nickel in a trans [O∧N(Ni2+)N∧O] fashion. Hence, in a molecule of 4, two ligands are four coordinate to a Ni(II) center through the imine nitrogen and naphthyloxyl oxygen atoms. This coordination mode resulted in a square planar complex that is stabilized in the solid-state by a network of intermolecular O-H···N hydrogen bonds between neighboring molecules. The 1H NMR data showed the loss of the hydroxyl (OH) proton signal and an upfield shift of the metal-bound imine (-NH) proton signal, while the IR data also showed a lower energy shift in the absorption frequency of the imine (C = N) bond due to back donation from the coordinated Ni(II) center. As a catalyst for the transfer hydrogenation of a range of ketones, 4 showed good catalytic activity at a very low concentration of 0.1 mol% with 2-propanol as the model substrate. The catalyst is also effective for various related ketone substrates bearing a range of steric and electronic regulating groups.

Formation of a macrocycle from di-chloro-dimethyl-silane and a pyridoxalimine Schiff base ligand.

The reaction of di-chloro-dimethyl-silane with a polydentate Schiff base ligand derived from pyridoxal and 2-ethano-lamine yielded the macrocyclic silicon compound (8E,22E)-4,4,12,18,18,26-hexa-methyl-3,5,17,19-tetra-oxa-8,13,22,27-tetra-aza-4,18-disilatri-cyclo-[22.4.0.010,15]octa-cosa-1(24),8,10,12,14,22,25,27-octa-ene-11,25-diol, C24H36N4O6Si2. The asymmetric unit contains the half macrocycle with an intra-molecular O-H⋯N hydrogen bond between the imine nitro-gen atom and a neighbouring oxygen atom. The crystal structure is dominated by C-H⋯O and C-H⋯π inter-actions, which form a high ordered mol-ecular network.

Alkali metal complexes of an unsymmetrical imino–phosphanamidinate (N-P-N) ligand

The syntheses and characterization of alkali metal complexes of an unsymmetrical monoanionic imidazolin-2-imino–phosphanamidinate ligand, {NHIDippP(Ph)N(Dipp)}− {L}− [Dipp = 2,6-diisopropylphenyl] is reported. The protio-ligand [NHIDippP(Ph)NH(Dipp)] (LH) was obtained by the reaction of N-heterocyclic imine (NHI) and [PhP(Cl)NHDipp] in the presence of Et3N in toluene at room temperature. The lithium complex [{NHIDippP(Ph)N(Dipp)}Li(OEt2)] (1) (Et = ethyl) was synthesized by the reaction of the protio ligand LH and one equivalent LiCH2SiMe3 in diethyl ether at room temperature. The reaction of sodium or potassium hexamethyldisilazide [MN(SiMe3)2] (M = Na or K) with LH in 1:1 molar ratio yielded corresponding alkali metal complexes [{NHIDippP(Ph)N(Dipp)}Na(THF)] (2) and [{NHIDippP(Ph)N(Dipp)}K(THF)2] (3) respectively in good yield. The molecular structures of the protio-ligand LH and alkali metal complexes 1 and 3 were established by single-crystal X-ray diffraction analysis. In the solid-state structures of 1 and 3, the lithium and potassium ions are κ2 bonded to the monoanionic ligand moiety through the imine nitrogen and phosphanamidinate nitrogen atoms.

Synthesis and Diagnoses of New Metal Ions Complexes derived from Trimethoprim Schiff Bases

A New Schiff base (o-hydroxy benzylidene trimethoprim) derived from trimethoprim (known as a drug) was used as a ligand in this study, has been synthesized by condensation reaction from equal amounts of ortho hydroxybenzaldehyde and trimethoprim. This was then used for the preparation of new complexes by the reaction with Zinc and Manganese salts. The synthesized complexes were in the formula [M(OHTMP)2]X2 in the natural medium and [M(OHTMP)2-H] in basic medium (M=Zn, Mn, OHTMP = o-hydroxy benzylidene trimethoprim X= CH3COO, NO3, Cl2). The prepared complexes were diagnosed and characterized by employing FT-IR, 1H- NMR, CHN element analysis, molar conductivity, Molar refraction and flame atomic absorption techniques. Spectroscopic results proved the chelation behavior of this ligand. It coordinated to the metal ions as a tridentate ligand, via the imine nitrogen, azo methine, and phenolic oxygen atoms. According to the obtained results, octahedral geometry has been suggested for prepared complexes. The biological activities of the prepared ligand and complexes against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella spp.) have being conducted. Both, the ligand and complexes showed anti-bacterial activities, beter than that of the Trimethoprim.