Containing‐PMBP N2O2‐donors transition metal(II) complexes: Synthesis,crystal structure,Hirshfeld surface analyses and fluorescence properties

Three newly designed containing‐PMBP N₂O₂‐donors complexes, [Co(L¹)(CH₃OH)₂] ( 1 ), [{Zn(L²)(CH₃OH)(H₂O)}₃] ( 2 ) and [Cu₄(L²)₄]?2CHCl₃ ( 3 ), have been synthesized and structurally characterized using elemental analyses, infrared and UV–visible spectroscopies and single‐crystal X‐ray diffraction. X‐ray crystal structure determinations revealed that 1 consists of one Co(II) atom, one completely deprotonated (L¹)^2? unit and two coordinated methanol molecules. Complex 2 consists of three Zn(II) atoms, three completely deprotonated (L²)^2? units, three coordinated methanol molecules and three coordinated water molecules. However, 3 includes four Cu(II) atoms, four completely deprotonated (L²)^2? units and two crystallization chloroform molecules. The Co(II) and Zn(II) atoms in the structures of 1 and 2 adopt slightly distorted octahedral geometries. While, Cu(II) atoms in 3 can be best described as adopting slightly distorted square planar geometries. Complex 2 is a novel structure, and the ratio of H₂L² to Zn(II) atom is 3:3. In addition, two‐, three‐ and three‐dimensional supramolecular structures were constructed for 1 , 2 and 3 . Most importantly, Hirshfeld surface analysis of 1 , 2 and 3 was conducted and fluorescence properties were investigated.     

Binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes with Schiff-bases derived from crown ether platforms: Rare examples of ether oxygen atoms bridging metal centers

Bibracchial lariat ethers L³ and L⁴, derived from the condensation of N,N′-bis(2-aminobenzyl)-1,10-diaza-15-crown-5 or N,N′-bis(2-aminobenzyl)-4,13-diaza-18-crown-6 with salicylaldehyde, form binuclear complexes with Co(II), Ni(II), Cu(II) and Zn(II). Our studies show that the different denticity and crown moiety size of the two related receptors give rise to important differences on the structures of the corresponding complexes. Single crystal X-ray diffraction analysis shows that the [Ni₂(L³)(H₂O)₂]²⁺ and [Cu₂(L³)(NO₃)]⁺ complexes constitute a rare example in which an oxygen atom of the crown moiety is bridging the two six coordinate metal ions. In contrast, none of the oxygen atoms of the crown moiety is acting as a bridging donor atom in the [Co₂(L⁴)(CH₃CN)₂]²⁺, [Cu₂(L⁴)]²⁺ and [Zn₂(L⁴)]²⁺ complexes. This is attributed to the larger size the crown moiety and the higher denticity of L⁴ compared to L³. In [Co₂(L⁴)(CH₃CN)₂]²⁺ the metal ions show a distorted octahedral coordination, while in the Cu(II) and Zn(II) analogues the metal ions are five-coordinated in a distorted trigonal bipyramidal environment. In [Cu₂(L³)(NO₃)]⁺ the coordinated nitrate anion acts as a bidentate bridging ligand, which results in the formation of a 1D coordination polymer.     

Heteronuclear complexes of oxorhenium(V) with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) and their biological activities

Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO₂(VI) ions were prepared by the reaction of the complex ligands [ReO(HL¹)(PPh₃)(OH₂)Cl]Cl (a) and/or [ReO(H₂L²)(PPh₃)(OH₂)Cl]Cl (b), where H₂L¹?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H₃L²?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1?:?1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO₂(VI) and Cu(II) using 2?:?1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N⁷ group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO₂(VI)?complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and ¹H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics.     

Nickel(II)-triphenylphosphine complexes of ONS and ONN chelating 2-hydroxyacetophenone thiosemicarbazones

The complexes [Ni(L¹)(PPh₃)] (1) and [Ni(L²)(PPh₃)]·HCl (2) were synthesized by the reaction of [Ni(PPh₃)Cl₂] and dibasic 2-hydroxyacetophenone-S-R-4-R¹-thiosemicarbazones (R/R¹: H/CH₃, L¹H₂; CH₃/H, L²H₂). The ligands and the complexes were characterized using elemental analysis, IR and ¹H NMR spectra. In both complexes, the thiosemicarbazone ligands coordinate to nickel(II) by giving two protons. Complex 1 is formed through the phenolate oxygen, azomethine nitrogen and sulfur atoms of L¹ and the P atom of a triphenylphosphine ligand. In complex 2, L² is functional through an ONN donor set, containing a thioamide nitrogen instead of a sulfur atom. X-ray analysis indicated distorted square planar structures for the complexes, and the nickel atoms lie slightly above the planes structured by the donor atoms. In the crystal forms of 1 and 2, some phenyl ring protons of the phosphine ligand give intramolecular hydrogen bonds with the donor atoms of the thiosemicarbazone moiety, namely the phenolate oxygen (in complexes 1 and 2) and N⁴ nitrogen (in complex 2).     

Synthesis and crystal structure of some new cadmium (II) macrocyclic Schiff-base complexes containing piperazine moiety

The metal templated Cd(II) cyclocondensation of 2,6-diacetylpiridine or 2,6-pyridinedicarbaldehyde and two different amines containing piperazine moieties have been investigated. The resulting ligands, L¹ and L² are 16- and L³ and L⁴ 17-membered pentaaza macrocycles. The complexes have been characterized by a variety of methods including IR, ¹H, ¹³C NMR, DEPT, COSY(H,H), HMQC(H,C), FAB spectrometry and conductivimetry measurements. The crystal structures of [CdL²Cl](CH₃OH)ClO₄ (2) and [CdL⁴(NO₃)(H₂O)]ClO₄ (4) have been also determined, and it was shown that the geometry of the Cd(II) ion in the complexes is slightly distorted pentagonal pyramidal and pentagonal bipyramidal, respectively. The gas-phase structures of ligands, L² and L⁴ and their Cd(II) complexes have also theoretically studied.     

Construction of Mononuclear Copper(II) and Trinuclear Cobalt(II) Complexes Based on Asymmetric Salamo‐Type Ligands

Mononuclear copper(II) and trinuclear cobalt(II) complexes, namely [Cu(L¹)]₂ · CH₂Cl₂ and [{Co(L²)(EtOH)}₂Co(H₂O)] · EtOH {H₂L¹ = 4,6‐dichloro‐6′‐methyoxy‐2,2′‐[1,1′‐(ethylenedioxydinitrilo)dimethylidyne]diphenol and H₃L² = 6‐ethyoxy‐6′‐hydroxy‐2,2′‐[1,1′‐(ethylenedioxydinitrilo)dimethylidyne]diphenol}, were synthesized and characterized by elemental analyses, IR and UV/Vis spectroscopy, and single‐crystal X‐ray diffraction. In the Cu^II complex, the Cu^II atom is four‐coordinate, with a N₂O₂ coordination sphere, and has a slightly distorted square‐planar arrangement. Interestingly, the obtained trinuclear Co^II complex is different from the common reported 2:3 (L:Co^II) salamo‐type Co^II complexes. Infinite 2D layer supramolecular structures are formed via abundant intermolecular hydrogen bonding and π ··· π stacking interactions in the Cu^II and Co^II complexes.     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Synthesis,Structural Characterization,and Antimicrobial Activities of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Triazole‐based Azodyes

The synthesis and characterization of new transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3‐(2‐hydroxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL¹ ) and 3‐(2‐hydroxy‐3‐carboxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL² ) have been carried out. Their structures were confirmed by elemental analyses, thermal analyses, spectral and magnetic data. The IR and ¹H NMR spectra indicated that HL¹ and HL² coordinated to the metal ions as bidentate monobasic ligands via the hydroxyl O and azo N atoms. The UV‐Vis, ESR spectra and magnetic moment data revealed the formation of octahedral complexes [Mn L¹ (AcO)(H₂O)₃] ( 1 ), [Co L¹ (AcO)(H₂O)₃]·H₂O ( 2 ), [Mn L² (AcO)(H₂O)₃] ( 6 ) and [Co L² (AcO)(H₂O)₃] ( 7 ), [Ni L¹ (AcO)(H₂O)] ( 3 ), [Zn L¹ (AcO)(H₂O)]·H₂O ( 5 ), [Ni L² (AcO)(H₂O)] ( 8 ), [Zn L² (AcO)(H₂O)]·10H₂O ( 10 ) have tetrahedral geometry, whereas [Cu L¹ (AcO)(H₂O)₂] ( 4 ) and [Cu L² (AcO)(H₂O)₂]·5H₂O ( 9 ) have square pyramidal geometry.. The mass spectra of the complexes under EI‐con‐ ditions showed the highest peaks corresponding to their molecular weights, based on the atomic weights of ⁵⁵Mn, ⁵⁹Co, ⁵⁸Ni, ⁶³Cu and ⁶⁴Zn isotopes; besides, other peaks containing other isotopes distribution of the metal. Kinetic and thermodynamic parameters of the thermal decomposition stages were computed from the thermal data using Coats‐Redfern method. HL² and complexes 6 – 10 were found to have moderate antimicrobial activities against Staphylococcus aureus (gram positive), Escherichia coli (gram negative) and Salmonella sp bacteria, and antifungal activity against Fusarium oxysporum, Aspergillus niger and Candida albicans. Also, in most cases, metallation increased the activity compared with the free ligand.     

Coenzyme M studies with nickel(II) compounds: Synthesis,structure, spectra and redox behaviors

Nickel(II) complexes of 1,6-bis(pyridyl)-2,5-dithiahexane (L¹), 1,7-bis(2′-pyridyl)-2,6-dithiaheptane (L²) and 1,9-bis(2′-pyridyl)-2,5,8-trithianonane (L³) have been prepared and their spectroscopic and redox behaviors were studied. [Ni(II)L¹(H₂O)₂](ClO₄)₂, and [Ni(II)L³(H₂O)](ClO₄)₂ were crystallized in single crystal form; their structures were solved by X-ray crystallography. The structures of the complexes are of distorted octahedral geometry. A red shift in the electronic spectra and a positive potential shift in electrochemical studies were detected during the addition of the sodium salt of 2-mercaptoethanesulfonic acid (CoM) to Ni(II) complexes containing L¹ and L². The high redox potential shifting difference (PSD) was observed with the addition of CoM to [NiL¹]²⁺, which accounts for the axial coordination of CoM with the nickel ion. However, [Ni(II)L³]²⁺ does not respond well with CoM addition due to the structural limitation around the Ni(II) ion. A destabilization of [Ni(II)L¹]²⁺ and [Ni(II)L²]²⁺ complexes and stabilization for [Ni(II)L³]²⁺ were noticed in their redox studies and these trends were inversely changed during anaerobic CoM addition to Ni(II) complexes. A nephelauxetic effect (β values) has been shown to establish a good relation with PSD.     

Synthesis,structure, and DNA binding of three reduced amino-acid Schiff-base zinc(II), nickel(II), and cadmium(II) complexes

Three new reduced amino-acid Schiff-base complexes, [Zn(HL)₂] · H₂O (1), [Ni(HL)₂] · H₂O (2), and [Cd(HL)₂] · H₂O (3), where H₂L is a reduced Schiff base derived from condensation of N-(2-hydroxybenzaldehyde) and L-histidine, have been synthesized and characterized by elemental analysis, UV-Vis absorption spectra and single crystal X-ray diffraction. Complexes 1–3 are isostructural. All metal centers are six-coordinate with O₂N₄ donor sets in slightly distorted octahedra. Unlike its Schiff-base counterpart, the deprotonated monoanionic ligand HL^? has a more flexible backbone and two HL^? are tridentate to one metal. Moreover, the binding interactions of these complexes with calf thymus DNA (CT-DNA) have been investigated by UV-Vis spectra and fluorescence quenching, which show that the complexes bind in an intercalative mode.     

Pyrrole‐2‐carbaldehyde Thiosemicarbazonates of Nickel(II) and Palladium(II): Synthesis,Structure, and Spectroscopy

Complexes of pyrrole‐2‐carbaldehyde thiosemicarbazones, [(C₄H₄N⁴)(H)C²=N³–N²(H)–C¹(=S)–N¹HR; R = Ph, H₂L¹; Me, H₂L²; H, H₂L³] with nickel(II) and palladium(II) are described. The reaction of nickel(II) acetate with H₂L¹ in methanol in 1:1 molar ratio yielded a complex of composition, [Ni(κ²‐N³,S‐HL¹)₂] ( 1 ). Likewise reaction of NiCl₂ with H₂L² in 1:1 molar ratio in acetonitrile in the presence of triethylamine base followed by the addition of pyridine did not yield the anticipated [Ni(κ³‐N⁴,N³,S‐L²)(py)] complex, moreover a bis‐square‐planar complex, [Ni(κ²‐N³,S‐HL²)₂] ( 2 ) was formed. However, in the presence of bipyridine (bipy), it yielded the addition product, [Ni(κ²‐N³,S‐HL²)₂(κ²‐N, N‐bipy)] ( 3 ). Reaction of PdCl₂(κ²‐P, P–PPh₂–CH₂–PPh₂) with H₂L³ in toluene in the presence of triethylamine has yielded a complex of stoichiometry, [Pd(κ³‐N⁴,N³,S–L³)(κ¹‐P–PPh₂–CH₂–P(O)Ph₂] ( 4 ). The ligands (HL¹)^– and (HL²)^– are chelating to Ni^II metal atom as anions binding through N³,S‐donor atoms with pendant pyrrole groups, and (L³)^2– is chelating to the Pd^II metal atom as dianion through N⁴,N³,S‐donor atoms (pyrrole is N⁴‐bonded). Fourth site in 4 is bonded to one P‐donor atom of PPh₂–CH₂–P(O)Ph₂, whose pendant –PPh₂ group involves auto oxidation to –P(O)PPh₂ during reaction. These complexes were characterized using analytical data, IR, NMR (¹H, ³¹P) spectroscopy and X‐ray crystallography. Complexes 1 , 2 , and 4 have square‐planar arrangement, whereas complex 3 is octahedral.     

Synthesis and structural characterization of nickel(II), copper(II) and zinc(II) complexes with the hexadentate ligand 2,13-bis(2-pyridylmethyl)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane

The complexes [Ni(L²)]Cl₂·10H₂O (1), [Cu(L²)](ClO₄)₂·3H₂O (2), [Cu₂(L²)(H₂O)₂Cl₂]Cl₂ (3) and [Zn(L²)]Cl₂·10H₂O (4) (L²=2,13-bis(2-pyridylmethyl)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) have been synthesized and characterized by X-ray crystallography, electronic absorption, ¹³C NMR and magnetic susceptiblity as well as cyclic voltammetry. The crystal structures of 1 and 4 show that the metal ion has a slightly distorted octahedral geometry with two nitrogen atoms of the pendant arms at the axial positions. However, 2 exhibits a square-planar geometry, coordinated by secondary and tertiary nitrogen donors of the macrocycle. Furthermore, 3 reveals a binuclear structure and a center of symmetry in which the each copper ion is coordinated by a distorted square-pyramidal geometry with an N₃Cl basal plane and a water molecule in the apical position. The magnetic behavior for 3 shows that a ferromagnetic interaction between the copper(II) ions is predominant at intermediate temperature and then a weaker antiferromagnetic coupling is involved at lower temperature. Cyclic voltammetric studies for 1–3 indicate that 1 undergoes quasi-reversible one-electron oxidation to the Ni(III) and reversible one-electron reduction to the Ni(I), 2 undergoes a irreversible one-electron reduction to the Cu(I) state, while 3 undergoes an overall quasi-reversible two-electron reduction to the binuclear Cu(I) complex.     

Synthesis,Properties and X-ray Crystal Structures of Nickel(II) Complexes of a Hexaazamacrotetracyclic Ligand

The complexes [N₂(L²)₂(H₂O)₄]Cl₄(1) and [Ni(L²)](ClO₄)₂ [sdot]2H₂O (2) (L = 1,3,10,12,16,19-hexaazatetracyclo [17,3,1,1 ^12.16,0^4.9]tetracosane) have been synthesized and structurally characterized by X-ray crystallography, spectroscopic and cyclic voltammetry. The crystal structure of 1 has a distorted octahedral geometry with two secondary and two tertiary amines of the macrocycle and two water molecules. In 2, the coordination geometry around the nickel atom is square-planar with four nitrogen atoms of the macrocycle. The equilibrium [Ni(L²)]²⁺ + 2H₂O &rlhar2; [Ni(L²)(H₂O)₂]²⁺ has been studied in aqueous solution over a temperature range, yielding Δ H° = -19.0 ± 0.2 kJ mol^-1 and Δ S° = - 56.0 ± 0.4 JK^-1 mol^-1. Cyclic voltammetry of the complexes give two one-electron waves corresponding to Ni(II)/Ni(III) and Ni(II)/Ni(I) processes. The electronic spectra and redox potentials of the complexes are influenced significantly by the geometry.     

五-和六配位的三核锌配合物{[ZnL(OAc)]2Zn}∙CH3COCH3的合成，晶体结构及荧光性质

合成并结构表征了一种新型的线性三核锌(II)配合物,{[ZnL(OAc)]2Zn}∙CH3COCH3（H2L：乙二氧双(5-溴-2-羟基苯亚甲基胺)）。X-射线结构表明配合物中三个锌(II)离子配位到了两个四齿的L2-单元和两个桥联的的乙酸根基团。围绕两端的Zn(1) 或 Zn(1)#1原子形成了扭曲的四方锥配位几何体,围绕中心Zn(2) 原子构成了一个稍微扭曲的八面体配位结构。同时,观察到锌(II)配合物能发出蓝绿色荧光,其最大发射波长为464 nm。     

Ruthenium(II) complexes of aroylhydrazones: structural,electrochemical and electrostatic interactions with DNA

Four Ru(II) complexes with tridentate ligands viz. (4-hydroxy-N′-(pyridin-2-yl-ethylene) benzohydrazide [Ru(L¹)(PPh₃)₂(Cl)] (1), N′-(pyridin-2-yl-methylene) nicotinohydrazide [Ru(L²)(PPh₃)₂(Cl)] (2), N′-(1H-imidazol-2-yl-methylene)-4-hydroxybenzohydrazide [Ru(L³)(PPh₃)₂(Cl)] (3), and N′-(1H-imidazol-2-yl-methylene) nicotinohydrazide [Ru(L⁴)(PPh₃)₂(Cl)] (4) have been synthesized and characterized. The methoxy-derivative of L³H (abbreviated as L³H*) exists in E configuration with torsional angle of 179.4° around C₇-N₈-N₉-C₁₀ linkage. Single crystal structures of acetonitrile coordinated ruthenium complexes of 1 and 3 having compositins as [Ru(L¹)(PPh₃)₂(CH₃CN)]Cl (1a) and [Ru(L³)(PPh₃)₂(CH₃CN)]Cl (3a) revealed coordination of tridentate ligands with significantly distorted octahedral geometry constructed by imine nitrogen, heterocyclic nitrogen, and enolate amide oxygen, forming a cis-planar ring with trans-placement of two PPh₃ groups and a coordinated acetonitrile. Ligands (L¹H-L⁴H) and their ruthenium complexes (1–4) are characterized by ¹H, ¹³C, ³¹P NMR, and IR spectral analysis. Ru(II) complexes have reversible to quasi-reversible redox behavior having Ru(II)/Ru(III) oxidation potentials in the range of 0.40–0.71 V. The DNA binding constants determined by absorption spectral titrations with Herring Sperm DNA (HS-DNA) reveal that L⁴H and 1 interact more strongly than other ligands and Ru(II) complexes. Complexes 1–3 exhibit DNA cleaving activity possibly due to strong electrostatic interactions while 4 displays intercalation.     

Structural characterization,thermal stability,and solvent de-/ad-sorption behavior of two d10 M(II) (M = Cd and Zn) coordination polymers constructed by 1,3,5-tris(4-pyridylsulfanyl-methyl)-2,4,6-trimethyl-benzene (L1)

Two d¹⁰ M(II) (M = Cd and Zn) coordination polymers (CPs) with chemical formulas, {[Cd(L¹)(NCS)₂(H₂O)]⋅C₂H₅OH}_n (1) , and {[Zn(L¹)(NCS)₂]⋅C₂H₅OH⋅0.5H₂O}_n (2) (L¹ = 1,3,5-tris(4-pyridylsulfanylmethyl)-2,4,6-trimethylbenzene) were synthesized and structurally characterized by single-crystal x-ray diffraction method. In compound 1 , the coordination environment of Cd(II) ion is distorted octahedral bonded to three nitrogen donors from three L¹ ligands located in a facial-position, two nitrogen donors from NCS⁻ and one water molecule. The L¹ acts as a bridge ligand with tris-monodentate coordination mode in a cis-cis-cis structural conformation, connecting the Cd(II) to form a two-dimensional (2D) zigzag-like layered metal-organic frameworks. Adjacent 2D layers are then arranged orderly in an ABAB manner to complete its three-dimensional (3D) supramolecular architecture. In compound 2 , the coordination environment of Zn(II) ion is distorted tetrahedral bonded to two nitrogen donors from two L¹ ligands and two nitrogen donors from two NCS⁻ ligands. The L¹ acts as a bridge ligand with bis-monodentate coordination mode in a cis-cis-cis structural conformation, connecting the Zn(II) ions to form a one-dimensional (1D) zigzag-like polymeric chain. Adjacent chains are arranged orderly in an alternate ABAB manner to generate a 2D framework and then further arranged in an AAA manner to complete its 3D supramolecular architecture. The structural characterization as well as thermal-stability and solvents de-/ad-sorption behavior of 1 and 2 are studied and discussed in details.     

Cu(II) and Pd(II) complexes of N-(2-hydroxybenzyl)aminopyridines

N-(2-Hydroxybenzyl)aminopyridines (Lⁱ) react with Cu(II) and Pd(II) ions to form complexes in the compositions Cu(Lⁱ)₂(CH₃COO)₂ · nH₂O (n = 0, 2, 4), Pd(Lⁱ)₂Cl₂ · nC₂H₅OH (n = 0, 2) and Pd(L²)₂Cl₂ · 2H₂O. In the complexes, the ligands are neutral and monodentate which coordinate through pyridinic nitrogen. Crystal data of the complexes obtained from 2-amino pyridine derivative have pointed such a coordinating route and comparison of the spectral data suggests the validity of similar complexation modes of other analog ligands. Cu(II) complex of N-(2-hydroxybenzyl)-2-aminopyridine (L¹), [Cu(L¹)₂(CH₃COO)₂] has slightly distorted square planar cis-mononuclear structure which is built by two oxygen atoms of two monodentate carboxylic groups disposed in cis-position and two nitrogen atoms of two pyridine rings. The remaining two oxygen atoms of two carboxylic groups form two Cu and H bridges containing cycles which joint at same four coordinated copper(II) ion. IR and electronic spectral data and the magnetic moments as well as the thermogravimetric analyses also specify on mononuclear octahedric structure of complexes [Cu(L²)₂(CH₃COO)₂ · 2H₂O] and [Cu(L³)₂(CH₃COO)₂ · 4H₂O] where L² and L³ are N-(2-hydroxybenzyl)-2- or 3-aminopyridines, respectively.     

Synthesis,crystal structure,and antibacterial activity of mononuclear nickel(II) and cobalt(III) Schiff-base complexes

Four new mononuclear complexes, [Ni(L¹)(NCS)₂] (1), [Ni(L²)(NCS)₂] (2), [Co(L¹)(N₃)₂]ClO₄ (3), and [Co(L²)(N₃)₂]ClO₄ (4), where L¹ and L² are N,N′-bis[(pyridin-2-yl)methylidene]butane-1,4-diamine and N,N′-bis[(pyridin-2-yl)benzylidene]butane-1,4-diamine, respectively, have been prepared. The syntheses have been achieved by reaction of the respective metal perchlorate with the tetradentate Schiff bases, L¹ and L², in presence of thiocyanate (for 1 and 2) or azide (for 3 and 4). The complexes have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 are distorted octahedral geometries. The antibacterial activity of all the complexes and their constituent Schiff bases have been tested against Gram-positive and Gram-negative bacteria.     

Synthesis,crystal structure and antibacterial activity of manganese(III) and cobalt(III) complexes containing pentadentate Schiff bases of a common amine and thiocyanate

Abstract

Four new mononuclear Schiff base manganese(III) and cobalt(III) complexes viz. [Mn(L¹)(NCS)] (1), [Mn(L²)(NCS)] (2), [Co(L³)(NCS)] (3), and [Co(L⁴)(NCS)]·0.5CH₃OH·0.5H₂O (4), containing thiocyanate as a common pseudohalide ion are reported. The pentadentate Schiff base ligands H₂L¹, H₂L², H₂L³, and H₂L⁴ were obtained by the condensation of substituted salicylaldehydes with N-(3-aminopropyl)-N-methylpropane-1,3-diamine. The syntheses of the complexes have been achieved by the reaction of manganese(II) perchlorate or cobalt(II) perchlorate with the respective Schiff bases in the presence of thiocyanate in methanol medium. Complexes 1–4 have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 adopt nearly similar structures containing the MN₄O₂ (M?=?Mn, Co) chromophore in which each central M(III) ion adopts a distorted octahedral geometry. Weak intermolecular H-bonding interactions are operative in these complexes to bind the molecular units. The antibacterial activity of 1–4 and their constituent Schiff bases has been tested against some common bacteria.     

Synthesis and characterization of nickel(II) complexes with three potentially hexadentate Schiff-base ligands and polyamines: X-ray crystal structure determination of one nickel(II) complex

Three new potentially hexadentate N₄O₂ Schiff-base ligands (H₂L¹, H₂L² and H₂L³) were prepared from the reaction of the polyamines N,N′-bis(2-aminophenyl)-1,2-ethanediamine (L¹), N,N′-bis(2-aminophenyl)-1,3-propanediamine (L²) and N,N′-bis(2-aminophenyl)-1,4-butanediamine (L³), respectively with salicylaldehyde. Reaction of the Schiff bases with Ni(II) salts in the presence of N(Et)₃ gave the neutral complexes [NiL⁴], [NiL⁵] and [NiL⁶]. Ni(II) complexes of the polyamines were also prepared. One of complexes [Ni(L¹)(MeCN)₂](ClO₄)₂·MeCN has been characterized through X-ray diffraction methods.