New diorganotin(IV) complexes with some Schiff bases derived from β-diketones: synthesis,spectral properties,thermal analysis,and antibacterial activity

The Schiff bases H₂L^a, H₂L^b, and H₂L^c have been prepared from the reaction of 2-amino-4-chlorophenol with acetylacetone, benzoylacetone, and dibenzoylmethane, respectively. Organotin(IV) complexes [SnPh₂(L^a)] (1), [SnPh₂(L^b)] (2), [SnPh₂(L^c)] (3), and [SnMe₂(L^c)] (4) have been synthesized from the reaction of SnPh₂Cl₂ and SnMe₂Cl₂ with these Schiff bases. The synthesized complexes have been characterized by elemental analysis and FT-IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectroscopy. Spectroscopic data suggest the Schiff bases are completely deprotonated and coordinated tridentate to tin via imine nitrogen and phenolic and enolic oxygen atoms; the coordination number of tin is five. Thermal decomposition of the complexes has been studied by thermogravimetry. The in vitro antibacterial activities of the Schiff bases and their complexes have been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. H₂L^a, H₂L^c, and all complexes exhibited good activities and have potential as drugs.     

Interconversion of Highly Entangled Polyhedra into Concave Polyhedra by Nitrate-Induced Ternary Coordination

Entangled (M₃L₂)_n polyhedral complexes represent a unique class of supramolecular architectures that are stabilized by relatively weak metal–acetylene interactions in cooperation with conventional metal–pyridyl coordination. Counter-anion exchange of these complexes with a nitrate (NO₃⁻) ion triggered formal metal insertion between the metal centers, and a heteroleptic ternary coordination mode with acetylenic, pyridyl, and nitrate donors was generated on the metal centers. As a result, the main frameworks of the polyhedral complexes M₁₈L₁₂ and M₁₂L₈ were formally extended into a new series of concave polyhedra having the compositions M₂₁L₁₂ and M₁₃L₈, respectively. This transformation also resulted in the local disconnection of the highly entangled trifurcate topology of the framework, providing clues toward the skeletal editing of extended and complex three-dimensional (3D) architectures.     

Dioxouranium Complexes with Acetylpyridine Benzoylhydrazones and Related Ligands

Acetylpyridine benzoylhydrazone and related ligands react with common dioxouranium(VI) compounds such as uranyl nitrate or [NBu₄]₂[UO₂Cl₄] to form air‐stable complexes. Reactions with 2, 6‐diacetylpyridinebis(benzoylhydrazone) (H₂L^1a) or 2, 6‐diacetylpyridinebis(salicylhydrazone) (H₂L^1b) give yellow products of the composition [UO₂(L¹)]. The neutral compounds contain doubly deprotonated ligands and possess a distorted pentagonal‐bipyramidal structure. The hydroxo groups of the salicylhydrazonato ligand do not contribute to the complexation of the metal. The equatorial coordination spheres of the complexes can be extended by the addition of a monodentate ligand such as pyridine or DMSO. The uranium atoms in the resulting deep‐red complexes have hexagonal‐bipyramidal coordination environments with the oxo ligands in axial positions. The sterical strains inside the hexagonal plane can be reduced when two tridentate benzoylhydrazonato ligands are used instead of the pentadentate 2, 6‐diacetylpyridine derivatives. Acetylpyridine benzoylhydrazone (HL²) and bis(2‐pyridyl)ketone benzoylhydrazone (HL³) deprotonate and form neutral, red [UO₂(L)₂] complexes. The equatorial coordination spheres of these complexes are puckered hexagons. X‐ray diffraction studies on [UO₂(L^1a)(pyridine)], [UO₂(L^1b)(DMSO)], [UO₂(L²)₂] and [UO₂(L³)₂] show relatively short U—O bonds to the benzoylic oxygen atoms between 2.328(6) and 2.389(8) Å. This suggests a preference of these donor sites of the ligands over their imino and amine functionalities (U—N bond lengths: 2.588(7)—2.701(6) Å ).     

CO2-fixation into carbonate anions for the construction of 3d-4f cluster complexes with salen-type Schiff base ligands: from molecular magnetic refrigerants to luminescent single-molecule magnets

Six new carbonate-bridged Zn₂Ln₂ cluster complexes derived from salen-type Schiff base ligands [H₂L^a = N, N′-bis(3-methoxysalicylidene)-1,3-diaminopropane and H₂L^b = N, N′-bis(3-methoxysalicylidene)- 1,2-diaminoethane] have been synthesized. The bis-imine chain in Schiff base ligands have an obvious influence on the cluster complexes' structures, magnetic and luminescence properties. The carbonate bridging ligand exactly comes from autoimmobilization of carbon dioxide, which may mediate ferromagnetic coupling between Ln³⁺ ions, favoring magnetocaloric effects and single molecule magnet (SMM) properties. Complexes Zn₂Dy₂(μ³-CO₃)₂(L^a)₂(NO₃)₂(MeOH)₂ ( 1 ) and [Zn₂Dy₂(μ³-CO₃)₂(L^b)₂(NO₃)₂]·2MeOH ( 2) show field-induced SMM properties; complexes Zn₂Tb₂(μ³-CO₃)₂(L^a)₂(NO₃)₂(MeOH)₂ ( 3 ) and [Zn₂Tb₂(μ³-CO₃)₂(L^b)₂(NO₃)₂]·2MeOH ( 4 ) display both luminescence and field-induced SMM behaviors; while complexes [Zn₂Gd₂(μ³-CO₃)₂(L^a)₂(NO₃)₂]·2MeOH ( 5 ) and [Zn₂Gd₂(μ³-CO₃)₂(L^b)₂(NO₃)₂]·2MeOH ( 6 ) exhibit medium magnetic entropy changes, which are candidates for cryogenic molecular magnetic refrigerants.     

Syntheses,characterization and anti‐microbial activities of palladium(II) and palladium(IV) complexes of 3,10‐C‐meso‐Me8[14]diene (L1) and its reduced isomeric anes (LA,LB and LC). Crystal and molecular structure of [PdL1][Pd(SCN)4]

The reactions of 3,10‐C‐meso‐3,5,7,7,10,12,14,14‐octamethyl‐1,4,8,11‐tetraazacyclotetradecadiene, L¹, and two isomers (L_B and L_C, differing in the orientation of methyl groups on the chiral carbon atoms) of its reduced form with PdCl₂ and K₂[Pd(SCN)₄], produce square‐planar tetrachloro‐ and tetrathiocyano‐palladium(II) complexes of general formulae [PdL′][PdCl₄] and [PdL′][Pd(SCN)₄] (L′ = L¹, L_B and L_C), respectively. By contrast, the third ane isomer, L_A, upon reaction with the same reagents, PdCl₂ and K₂[Pd(SCN)₄], formed octahedral tetrachloro‐ and tetrathiocyanato‐palladium(IV) complexes [PdL_ACl₂]Cl₂ and [PdL_A(SCN)₂](SCN)₂, respectively. The [PdL′][PdCl₄] and [PdL_ACl₂]Cl₂ complexes undergo substitution reactions with KSCN to form square‐planar and octahedral tetrathiocyanato complexes [PdL′][Pd(SCN)₄] and [PdL_A(SCN)₂](SCN)₂, respectively. All complexes have been characterized on the basis of analytical, spectroscopic, conductometric and magnetochemical data. The anti‐fungal and anti‐bacterial activities of these complexes have been studied against some phytopathogenic fungi and bacteria. The crystal structure of [PdL¹][Pd(SCN)₄] has been confirmed by X‐ray crystallography and shows with square‐planar PdN₄ and PdS₄ geometries [monoclinic, space group C2/c, a = 17.884(3) Å, b = 14.734(2) Å, c = 11.4313(18) Å, β = 104.054(5)° ]. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and spectroscopic characterization of new heteroleptic ruthenium(II) complexes incorporating 2-(2′-pyridyl)quinoxaline and 4-carboxy-2-(2′-pyridyl)quinoline

Starting from cis-[Ru(dcbpyH₂)₂Cl₂] (1), two new heteroleptic ruthenium(II) complexes, [Ru(dcbpyH₂)₂(L¹)](NO₃)₂ (L^1?=?2-(2′-pyridyl)quinoxaline (2), and [Ru(dcbpyH₂)₂(L²)](NO₃)₂ (L^2?=?4-carboxy-2-(2′-pyridyl)quinoline (4); dcbpyH_2?=?2,2′-bipyridine-4,4′-dicarboxylic acid), were synthesized and spectroscopically characterized. During the preparation of 2 and 4, the homoleptic [Ru(dcbpyH₂)₃]Cl₂ complex (3) was isolated as a side product. Characterization includes IR and Raman spectroscopy, UV-Vis, multinuclear NMR spectroscopy, elemental, and ESI-mass spectrometric analyses.     

Coordination polymers and discrete complexes of Ag(I)-N-(pyridylmethylene)anilines: synthesis,crystal structures and photophysical properties

Reactions of AgO₂C₂F₃ with (E)-N-(pyridylmethylene)aniline in which the pyridyl N is in the p- or m-position yielded two 1-D coordination polymers, [(AgO₂C₂F₃)₂(L_a)₂]_n (L_a = (E)-2,6-diisopropyl-N-(pyrid-3-ylmethylene)aniline) (1) and [(AgOC₂F₃)₂(L_d)₂]_n (L_d = (E)-2,6-diisopropyl-N-(pyrid-4-ylmethylene)aniline) (5), and three discrete complexes, [(AgO₂C₂F₃)₂(L_a)₄] (2), [AgO₂C₂F₃(L_b)₂] (L_b = (E)-N-(pyrid-4-ylmethylene)aniline) (3) and [(AgOC₂F₃)₂(L_c)₄] (L_c = (E)-2,6-dimethyl-N-(pyrid-4-ylmethylene)aniline) (4). The structures were determined by MS, FT-IR and NMR spectroscopies, elemental analysis and single crystal XRD. 1 is an organometallic coordination polymer with silver in η¹-arene coordination, but is a discrete dimeric complex 2 when crystallized from warm diethylether. The geometries around silver(I) in 1 and 4 are tetrahedral, ‘inverted seesaw’ in 2 and T-shaped in 3 and in all the anion seems to play a role. Ag(I) centers in 5 have distorted trigonal bipyramid and inverted seesaw geometries. The trifluoroacetate anions in these complexes display variable monodentate and short bridging coordination patterns. All complexes absorb and strongly emit UV-Vis radiation at room temperature.     

Synthesis,crystal structure,redox behavior and DNA-binding properties of a series of copper(II) complexes with two new carboxamide derivatives

Four mononuclear copper(II) complexes of two new carboxamide derivatives formulated as [Cu(L¹)₂](ClO₄)₂ (1a), [Cu(L¹)₂](NO₃)₂ (1b), [Cu(L²)₂(H₂O)₂](ClO₄)₂ (2a), and [Cu(L²)₂(H₂O)](NO₃)₂ (2b) have been isolated in pure form from the reaction of L¹ and L² [where L¹ = N-(furan-2-ylmethyl)-2-pyridinecarboxamide and L² = N-(thiophen-2-ylmethyl)-2-pyridinecarboxamide] with copper(II) salts of perchlorate and nitrate. All the complexes were characterized by physicochemical and spectroscopic tools along with single-crystal X-ray diffraction studies. The structural analyses showed that 1 is monomeric of square planar geometry with copper(II) chelated by two L¹ ligands. Complex 2 differs in coordination geometry, being octahedral and distorted square pyramidal. Two L² ligands occupy the equatorial positions of the octahedral 2a and the basal sites of the pyramidal 2b, with water molecules that complete the coordination sphere in each case. Electrochemical studies using cyclic voltammetry showed a reversible redox behavior of the copper(II) in 1 and 2. The electronic spectroscopic behavior and the trend of one electron equivalent redox potential corresponding to a Cu^II/Cu^I couple have also been confirmed by density functional theory calculations. The spectroscopic and viscosity measurement study in tris–HCl buffer suggested an intercalative interaction of 1a and 2 with calf thymus DNA likely due to the stacking between the non-coordinated furan and thiophene chromophore with the base pairs of DNA.     

Synthesis and characterization of several rhenium(I) complexes of 2-acetylpyridine and ferrocenyl carbaldehyde derivatives of 2-hydroxybenzoic acid hydrazide

The rhenium(I) carbonyl halide (X = Cl and Br) complexes, [ReX(CO)₃{H₂(py)L²}] (1a, 1b) and [ReX(CO)₃{H₂(Fc)L²}] (2a, 2b), of the ligands derived from 2-acetylpyridine and ferrocenyl carbaldehyde derivatives of 2-hydroxybenzoic acid hydrazide [H₂(py)L² and H₂(Fc)L², respectively] have been prepared in good yield. The complexes have been characterized by elemental analysis, MS, IR, UV-Vis and ¹H NMR spectroscopic methods and their structures have been elucidated by X-ray diffraction. The ligand forms a five-membered chelate ring but in H₂(py)L² it is N_pyridine,N′-bidentate while it is O,N-bidentate in H₂(Fc)L² complexes.Reaction of complex 1a with copper(II) nitrate yields the unexpected aqua complex [Re{H(py)L²}(H₂O)(CO)₃] (3) where the ligand is monodeprotonated but maintains the coordination mode observed in 1a, as shown by X-ray diffraction. However, reaction of 1b with glycine yields a conformational polymorph of the original compound, 1b′. The X-ray study shows that the orientation of the O-H phenol group against the carbonyl amide group is the main difference.     

Synthesis,crystal structures,and catalytic oxidation properties of oxidovanadium(V) complexes with Schiff base ligands

Two new Schiff base ligands 2-chloro-N′-(5-fluoro-2-hydroxybenzylidene)benzohydrazide (H₂L^a) and 4-fluoro-2-{[2-(2-hydroxyethylamino)ethylimino]methyl}phenol (HL^b) were synthesized and characterized. Their respective oxidovanadium complexes, [VOL^a(OMe)(MeOH)]·MeOH (1) and [VO(μ-O)L^b]₂ (2), were synthesized and characterized by spectroscopy and single-crystal X-ray diffraction. The coordination sphere of each V atom is octahedral. Both complexes showed selective heterogeneous catalytic properties with 74–98 % conversion, for the oxidation of cyclohexene, cyclopentene, and benzyl alcohol using H₂O₂ as primary oxidant.     

Solvent dependence of the solid‐state structures of salicylaldiminate magnesium amide complexes

There are challenges in using magnesium coordination complexes as reagents owing to their tendency to adopt varying aggregation states in solution and thus impacting the reactivity of the complexes. Many magnesium complexes are prone to ligand redistribution via Schlenk equilibrium due to the ionic character within the metal–ligand interactions. The role of the supporting ligand is often crucial for providing stability to the heteroleptic complex. Strategies to minimize ligand redistribution in alkaline earth metal complexes could include using a supporting ligand with tunable sterics and electronics to influence the degree of association to the metal atom. Magnesium bis(hexamethyldisilazide) was reacted with salicylaldimines [¹L = N‐(2,6‐diisopropylphenyl)salicylaldimine and ²L = 3,5‐di‐tert‐butyl‐N‐(2,6‐diisopropylphenyl)salicylaldimine] in either nondonor (toluene) or donor solvents [tetrahydrofuran (THF) or pyridine]. The structures of the magnesium complexes were studied in the solid state via X‐ray diffraction. In the nondonor solvent, i.e. toluene, the heteroleptic complex bis{μ‐2‐[(2,6‐diisopropylphenyl)iminomethyl]phenolato}‐κ³N,O:O;κ³O:N,O‐bis[(hexamethyldisilazido‐κN)magnesium(II)], [Mg₂(C₁₉H₂₂NO)₂(C₆H₁₈NSi₂)₂] or [¹LMgN(SiMe₃)₂]₂, (1), was favored, while in the donor solvent, i.e. pyridine (pyr), the formation of the homoleptic complex {2,4‐di‐tert‐butyl‐6‐[(2,6‐diisopropylphenyl)iminomethyl]phenolato‐κ²N,O}bis(pyridine‐κN)magnesium(II) toluene monosolvate, [Mg(C₂₇H₃₈NO)₂(C₅H₅N)₂]·C₅H₅N or [{²L₂Mg₂(pyr)₂}·pyr], (2), predominated. Heteroleptic complex (1) was crystallized from toluene, while homoleptic complexes (2) and the previously reported [¹L₂Mg·THF] [Quinque et al. (2011). Eur. J. Inorg. Chem. pp. 3321–3326] were crystallized from pyridine and THF, respectively. These studies support solvent‐dependent ligand redistribution in solution. In‐situ¹H NMR experiments were carried out to further probe the solution behavior of these systems.     

Synthesis,spectral, catalytic,and thermal studies of vanadium complexes with quadridentate schiff bases

The paper reports the synthesis and characterization of vanadium complexes of N,N′-(±)-trans-bis(2,4-dihydroxyacetophenone)-1,2-cyclohexanediamine (H₂L¹) and N,N′-(±)-trans-bis(2,4-dihyroxy-5-nitroacetophenone)-1,2-chyclohexanediamine (H₂L²). All the complexes were characterized by elemental analysis, magnetic susceptibility measurements, infrared and electronic spectra, and thermogravimetric analysis. The X-ray patterns of the [VO(L¹)] · H₂O (I) and [VO(L²)] · H₂O (II) complexes show the monoclinic system with the unit cell parameters a = 26.1352, b = 11.7149, c = 6.0401 β = 115.38° and a = 29.3787, b = 12.9398, c = 5.9175 β = 96.84°, respectively. The complexes I and II catalyze the oxidation of styrene in the presence of hydrogen peroxide.     

Cyclopentadienyl pentafluorophenylthiolate complexes of molybdenum and tungsten as novel polydentate ligands of thallium(I); dynamic NMR studies and crystal structures of two derivatives [MoTl(SC6F5)2L2Cp] (L = SC6F5 or CO)

New bimetallic complexes [MTl(SC₆F₅)₂L₂Cp] (L = SC₆F₅, M = Mo (1a), W (1b); L = CO, M = Mo (4)) are characterised; crystal structures of 1a and 4 show unusual polydentate coordination of thallium(I) by [Mo(SC₆F₅)₂L₂Cp)]⁻ and var. temp. ¹⁹F NMR studies, supported by conductivity measurements and cation exchange, indicate restricted rotation of C₆F₅ groups and reversible decoordination of Tl⁺ in more polar solvents.     

Synthesis and physiochemical studies on binuclear Cu(II) complexes derived from 2,6-[(N-phenylpiperazin-1-yl)methyl]-4-substituted phenols

Preparation of the ligands HL¹ = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-ethylphenol; HL² = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-methoxyphenol and HL³ = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-nitrophenol are described together with their Cu(II) complexes with different bridging units. The exogenous bridges incorporated into the complexes are: hydroxo [Cu₂L(OH)(H₂O)₂](ClO₄)₂.H₂O (L¹=1a, L² =1b, L³ =1c), acetato [Cu₂L(OAc)₂]ClO₄.H₂O (L¹ =2a, L² =2b, L³ =2c) and nitrito [Cu₂L¹(NO₂)₂(H₂O)₂]ClO₄.H₂O (L¹=3a, L² =3b, L³ =3c). Complexes1a,1b,1c and2a,2b,2c contain bridging exogenous groups, while3a,3b,3c possess only open μ-phenolate structures. Both the ligands and complexes were characterized by spectral studies. Cyclic voltammetric investigation of these complexes revealed that the reaction process involves two successive quasireversible one-electron steps at different potentials. The first reduction potential is sensitive to electronic effects of the substituents at the aromatic ring of the ligand system, shifting to positive potentials when the substituents are replaced by more electrophilic groups. EPR studies indicate very weak interaction between the two copper atoms. Various covalency parameters have been calculated.     

Zinc(II) and cadmium(II) complexes having racemic and enantiomeric ligands: [Zn(La)2](NO3)2 · CH3CH2OH and [Cd(Lb)2Cl](ClO4) (La = D,L and Lb = D-(+)-1,2, 2-trimethylcyclopentane-1,3-diamine)

Two d¹⁰ transition-metal complexes having racemic and enantiomeric 1,2,2-trimethylcyclopentane-1,3-diamine ligands, [Zn(L_a)₂](NO₃)₂ · CH₃CH₂OH (1) and [Cd(L_b)₂Cl](ClO₄) (2) (L_a = D,L-1,2,2-trimethylcyclopentane-1,3-diamine, L_b = D-(+)-1,2,2-trimethylcyclopentane-1,3-diamine or (1R,3S)-1,2,2-trimethylcyclopentane-1,3-diamine), were synthesized and characterized by X-ray single-crystal diffraction. They crystallize in the Pbca and P2₁2₁2₁ space groups, respectively, and have different coordination numbers and coordination geometry (four-coordinate tetrahedron for Zn(II) in 1 and five-coordinate square-based pyramid for Cd(II) in 2) mainly due to their different ionic radii.     

Supramolecular Coordination Cages Based on N-Heterocyclic Carbene-Gold(I) Ligands and Their Precursors: Self-Assembly,Structural Transformation and Guest-Binding Properties

The incorporation of functional groups into the cavity of discrete supramolecular coordination cages (SCCs) will bring unique functions and applications. Here, three dicarboxylate ligands (H₂ L1 Cl, H₂ L2 Cl and H₂ L3 Cl) containing N-heterocyclic carbene (NHC) precursors as linkers were introduced to construct SCCs by combining with two C₃-symmertic (CpZr)₃(μ₃-O)(μ₂-OH)₃ clusters as three-connect vertices, resulted in a series of rugby-like V₂E₃ (V=vertex, E=edge) type homoleptic cages ( SCC-1 , SCC-2 and SCC-3 ). However, V₄E₆-type tetrahedral cages ( SCC-4 and SCC-5 ), incorporating six Au-NHC moieties, were obtained when the corresponding NHC-gold(I) functionalized ligands (H₂ L1 ^Au, H₂ L2 ^Au) were applied. For the first time, we present a trackable CpZr-involved cage to cage conversion to generate a heteroleptic V₂E₃ cage ( SCC-6 ) from two homoleptic cages ( SCC-2 and SCC-5 ) with different geometries of V₂E₃ and V₄E₆. The heteroleptic assembly SCC-6 can also be formed upon a subcomponent displacement strategy. The structural transformation and reassembly processes were detected and monitored by ¹H NMR spectroscopy and electrospray-ionization mass spectrometry. The formation of heteroleptic assembly was further supported by single crystal X-ray diffraction analysis. Moreover, homoleptic cage SCC-2 possesses a trigonal bipyramidal cationic cavity allowing the encapsulation of a series of sulfonate anionic guests.     

Influence of Peripheral Substitution on the Magnetic Behavior of Single‐Ion Magnets Based on Homo‐ and Heteroleptic TbIII Bis(phthalocyaninate)

A series of homoleptic ([Tb^III(Pc)₂]) and heteroleptic ([Tb^III(Pc)(Pc′)]) Tb^III bis(phthalocyaninate) complexes that contain different peripheral substitution patterns (i.e., tert‐butyl or tert‐butylphenoxy groups) have been synthesized in their neutral radical forms and then reduced into their corresponding anionic forms as stable tetramethylammonium/tetrabutylammonium salts. All of these compounds were spectroscopically characterized and their magnetic susceptibility properties were investigated. As a general trend, the radical forms exhibited larger energy barriers for spin reversal than their corresponding reduced compounds. Remarkably, heteroleptic complexes that contain electron‐donor moieties on one of the two Pc ligands show higher effective barriers and blocking temperatures than their homoleptic derivatives. This result is assigned to the elongation of the N? Tb distances in the substituted macrocycle, which brings the terbium(III) ion closer to the unsubstituted Pc, thus enhancing the ligand‐field effect. In particular, heteroleptic [Tb^III(Pc)(Pc′)] complex 4 , which contains one octa(tert‐butylphenoxy)‐substituted Pc ring and one bare Pc ring, exhibits the highest effective barrier and blocking temperature for a single‐molecule magnet reported to date.     

Diorganotin Complexes with N(4)-Phenylthiosemicarbazones: Synthesis,Spectroscopic Characterization,and Antibacterial Activity

Abstract

The organotin(IV) complexes, SnPh₂L^a (1), SnMe₂L^a (2), SnBu₂L^a (3), SnPh₂L^b (4), SnMe₂L^b (5), SnPh₂L^c (6), SnMe₂L^c (7), and SnBu₂L^c (8) were obtained by reaction of SnR ₂Cl₂ (R = Ph, Me, and Bu) with 1-(5-bromo-2-hydroxybenzylidene)-4-phenylthiosemicarbazide (H₂L^a), 1-((2-hydroxynaphthalen-1-yl)methylene)-4-phenylthiosemicarbazide (H₂L^b), and 1-(2-hydroxy-3-methoxybenzylidene)-4-phenylthiosemicarbazide (H₂L^c). The synthesized complexes have been investigated by elemental analysis, IR, ¹H NMR, and ¹¹⁹Sn NMR spectroscopy. The data show that the thiosemicarbazone acts as a tridentate dianionic ligand and coordinates via the thiol group, imine nitrogen, and phenolic oxygen. The coordination number of tin is 5. The in vitro antibacterial activities of the ligands and their complexes have been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and compared with the standard antibacterial drugs.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the following free supplemental files: Additional figures and tables]     

Synthesis of uranium complexes incorporating extended azo-imine ligands: Molecular and electronic structure

The new azo-imine ligands 2,4-di-tert-butyl-6-((2-((2-hydroxyphenyl)diazenyl) phenylimino)methyl)phenol, H₂L¹, 1a, and 2,4-di-tert-butyl-6-((2-((2-hydroxyphenyl) diazenyl)p-chlorophenylimino)phenol, H₂L², 1b, were prepared. Reaction of H₂L¹;1a, and H₂L²;1b, with uranyl nitrate hexahydrate afforded the mononuclear complexes of compositions [U(O)₂(L¹)(H₂O)]; 2a, and [U(O)₂(L²)(H₂O)]; 2b, complexes respectively. The newly synthesised ligands (1a and 1b) and the complexes (2a and 2b) were characterised unequivocally. The x-ray structure of 2a was determined. The tetradentate dianionic ligand (L¹)^2- coordinated the uranium ion equatorially with a water molecule in the same plane. Two axially coordinated oxo ligands completed the overall pentagonal bipyramid geometry around U(VI) ion. Structural pattern, electron transfer properties (oxidation near 1.32 ​V vs Ag/AgCl) and electronic transitions of [U(O)₂(L¹)(H₂O)]; 2a, and [U(O)₂(L²)(H₂O)]; 2b have been rationalized by DFT calculations.     

Synthesis and X‐Ray Single Crystal Structure of Two New Copper Complexes with the Redox Active Ligand 1,10‐Phenanthroline‐5,6‐dione

The synthesis and the crystal structures of the complexes [Cu(L^I)₂](ClO₄) ( 1 ) and [Cu(L^I)(CH₃CN)₂(ClO₄)₂] ( 2 ) are reported. 1 crystallizes in the monoclinic space group C2/c with the unit cell dimensions a = 13.169(4), b = 12.289(3), c = 14.732(3) Å, β = 109.03(2)° and Z = 4. Copper(I) is coordinated to four N atoms of the two 1,10‐Phenanthroline‐5,6‐dione (L^I) ligands with a two‐fold axis passing between the ligands. The copper(II) compound 2 crystallizes in the orthorhombic space group Pbn2₁ with unit cell dimensions of a = 7.498(5), b = 23.492(7), c = 12.363(4) Å and Z = 4. Copper(II) coordination can be described as a distorted octahedron with the N donor atoms of one L^I ligand and of two molecules of CH₃CN occupying the equatorial positions completed by two oxygen atoms of the two perchlorate molecules in the axial positions.