Mononuclear Formamidinate Complexes of Lithium and Sodium

Treatment of N,N′‐bis(aryl)formamidines (FXylH = N,N′‐bis(2,6‐dimethylphenyl)formamidine, FEtH = N,N′‐bis(2,6‐diethylphenyl)formamidine, FisoH = N,N′‐bis(2,6‐diisopropylphenyl)formamidine) with nBuLi in the presence of tmeda (= N,N,N′,N′‐tetramethylethylenediamine) led to deprotonation of the amidine affording [Li(FXyl)(tmeda)] ( 1 ), [Li(FEt)(tmeda)] ( 2 ) and [Li(Fiso)(tmeda)] ( 3 ) respectively. Similar treatment of FXylH and FisoH with [Na{N(SiMe₃)₂}] in THF and pmdeta (= N,N,N′,N″,N″‐pentamethyldiethylenetriamine) yielded [Na(FXyl)(pmdeta)] ( 4 ) and [Na(Fiso)(pmdeta)] ( 5 ). All complexes were characterised by spectroscopy (NMR and IR) and X‐ray crystallography. Due to the bulkiness of the formamidinate ligands and the multidentate nature of the supporting neutral amine ligands (tmeda and pmdeta), all compounds were mononuclear with η²‐chelating formamidinate ligands in the solid state.     

Preparation and Properties of Molybdenum and Tungsten Dinitrogen Complexes. 30.1 Syntheses of Zero-Valent Molybdenum Complexes with the DMF Ligand: The Crystal Structure of Trans-[Mo(CO)(DMF)(Ph2PCH2CH2PPh2)2]

Abstract

Treatment of trans-[Mo(N₂)₂(dpe)(dpm)] (dpe = Ph₂PCH₂CH₂PPh₂, dpm = Ph₂PCH₂PPh₂) or trans-[Mo(N₂)₂(dpe)(dpp)] (dpp = Ph₂PCH₂CH₂CH₂PPh₂) with excess DMF in benzene at reflux under Ar resulted in the formation of trans-[Mo(CO)(DMF)(dpe)(dpm)] or trans-[Mo(CO)(DMF)(dpe)(dpp)]. X-ray structural analysis of trans-[Mo(CO)(DMF)(dpe)₂] was performed using single crystals isolated as the minor product from the reaction mixture of trans-[Mo(N₂)₂(dpe)(dpp)] and DMF. Crystal data: C₅₆H₅₅O₂NP₄Mo, monoclinic, space group P2₁, a = 11.145(4), b = 23.425(5), c = 10.516(3) Å, β = 117.17(2)° V = 2442.6(13) ų, D _calcd = 1.35 g/cm³ for Z = 2. This disclosed the relatively long C O bond distance of the carbonyl ligand and the significantly short C=O bond length in the DMF ligand. When recrystallized from benzene/hexane under N₂, trans-[Mo(CO)(DMF)(dpe)(dpm)] was converted into trans-[Mo(CO)(N₂)(dpe)(dpm)].     

Mono- and binuclear complexes involving [Pd(N,N-dimethylethylenediamine)(H2O)2]2+, 4,4′-bipiperidine and DNA constituents

The Pd(dmen)Cl₂, where dmen?=?N,N-dimethethylenediamine, was synthesized and characterized by elemental analysis and spectroscopy. The complex-formation equilibria in the reaction of [Pd(dmen)(H₂O)₂]²⁺ with 4,4′-bipiperidine (Bip) and DNA constituents were investigated at 25°C and 0.1?mol?L^?1 ionic strength. The results show the formation of [(H₂O)(dmen)Pd(Bip)Pd(dmen)(H₂O)]⁴⁺. Inosine, uracil, and thymine interact with the previously mentioned complex by the substitution of two-coordinated water molecules. The formation constants of all possible mono- and binuclear complexes were determined and their speciation diagrams were evaluated.     

Coordination compounds of nickel with trithiocyanuric acid. Part IV. Structure of [Ni(pmdien)(ttcH)] (pmdien = N,N,N′,N′,N′′-pentamethyldiethylenetriamine,ttcH3 = trithiocyanuric acid)

Ni^II mixed-ligand complexes of compositions [Ni(pmdien)(ttcH)] (1), [Ni(baphen)₂(ttcH)] · 4H₂O (2), [Ni-(dpa)(ttcH)(H₂O)] (3), [Ni(cyclam)(ttcH)] · 2H₂O (4), [Ni(hexaa)](ttcH) (5) and [Ni(hexab)(ttcH)] · 2H₂O (6), (baphen = 4,7-diphenyl-1,10-phenanthroline, dpa = 2,2-dipyridylamine, cyclam = 1,4,8,11-tetraazacyclotetradecane, hexaa = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1^6,9]-octadecane, hexab = 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane) have been prepared and characterized by means of i.r., u.v.–vis. spectroscopies and magnetochemical measurements. The redox properties of the complexes were studied by cyclic voltammetry. The crystal and molecular structure of [Ni(pmdien)(ttcH)] was determined. The nickel atom is penta-coordinated by three N atoms of pmdien, and by S and N atoms of trithiocyanurate(2–) anion.     

Speciation of the Ternary Complexes of Vanadium(III)–Dipicolinic Acid with the Amino Acids Glycine,Proline, <Emphasis Type="Italic">α</Emphasis>-Alanine and <Emphasis Type="Italic">β</Emphasis>-Alanine Studied in 3.0 mol⋅dm<Superscript>−3</Superscript> KCl at 25 °C

In this paper we present speciation results for the ternary vanadium(III)–dipicolinic acid (H₂dipic) systems with the amino acids glycine (Hgly), proline (Hpro), α-alanine (Hα-ala), and β-alanine (Hβ-ala), obtained by means of electromotive forces measurements emf(H) using 3.0 mol⋅dm⁻³ KCl as the ionic medium and a temperature of 25 °C. The experimental data were analyzed by means of the computational least-squares program LETAGROP, taking into account hydrolysis of the vanadium(III) cation, the respective stability constants of the binary complexes, and the acid base reactions of the ligands, which were kept fixed during the analysis. In the vanadium(III)–dipicolinic acid–glycine system, formation of the ternary [V(Hdipic)(Hgly)]²⁺, [V(dipic)(Hgly)]⁺, [V(dipic)(gly)], [V(dipic)(gly)(OH)]⁻ and [V(dipic)(gly)(OH)₂]²⁻ was observed; in the case of the vanadium(III)–dipicolinic acid–proline system the ternary complexes [V(Hdipic) (Hpro)]²⁺, [V(dipic)(Hpro)]⁺, [V(dipic)(pro)] and [V(dipic)(pro)(OH)]⁻ were observed; in the vanadium(III)–picolinic acid–α-alanine were observed [V(Hdipic)(Hα-ala)]²⁺, [V(dipic) (Hα-ala)]⁺, [V(dipic)(αala)], [V(dipic)(α-ala)(OH)]⁻ and [V(dipic)(α-ala)(OH)₂]²⁻; and in the vanadium(III)–dipicolinic acid–β-ala system the complexes [V(dipic) (Hβ-ala)]⁺, [V(dipic)(β-ala)], [V(dipic)(β-ala)(OH)]⁻ and [V(dipic)(β-ala)(OH)₂]²⁻ were observed. Their respective stability constants were determined, and we evaluated values of Δlog ₁₀ K″ in order to understand the relative stability of the ternary complexes compared to the corresponding binary ones. The species distribution diagrams are briefly discussed as a function of pH.     

Synthesis of N,N‐Dialkyl‐9‐oxoacridine‐10(9H)‐carbothioamides via the Reaction of (2‐Halophenyl)(2‐isothiocyanatophenyl)methanones with Secondary Amines,Followed by Cyclization with NaH

The first preparation of acridin‐9(10H)‐ones carrying a tertiary thiocarbamoyl group at C(10), i.e., N,N‐dialkyl‐9‐oxoacridine‐10(9H)‐carbothioamides 9 , is described. The method is based on the reaction of (2‐halophenyl)(2‐isothiocyanatophenyl)methanones 7 , prepared from (2‐aminophenyl)(2‐halophenyl)methanones 5 by a convenient three‐step sequence, with secondary amines in DMF at room temperature to generate the corresponding thiourea derivatives 8 in situ, which are treated with NaH at 100–120° to provide the desired products in one‐pot reactions in generally good yields.     

Synthesis,Crystal Structure and DNA Cleavage Activity of a Ternary Copper(Ⅱ)Complex of Dipyrido[3,2-d:2',3'-f]-quinoxaline and Glycine

A ternary copper(II) complex, [Cu(Dpq)(Gly)(H₂O)]·NO₃·1.5H₂O (Dpq=dipyrido[3,2‐d:2′,3′‐f]quinoxaline, Gly=glycine), has been synthesized and structurally characterized. The complex crystallized in a triclinic system with space group P‐1, a=6.6979(9) Å, b=7.6351(10) Å, c=18.980(2) Å, α=85.815(2) °, β=88.182(2) °, γ=71.203(2) °. The five‐coordinate copper(II) center is a distorted square pyramid. Absorption spectra, fluorescence spectra and CD spectra showed that there were interactions between the copper complex and DNA through a groove binding mode. The complex exhibited efficient DNA cleavage activity at micromolar concentration in the presence of ascorbate with hydroxyl radicals as the active species.     

Synthesis,characterization, and antimicrobial properties of two Cu(II) complexes derived from a benzimidazole ligand

Two copper(II) complexes, [Cu(L)₂](ClO₄)₂] and [Cu(L)(bipy)](ClO₄)₂, were prepared and characterized by the spectroscopic and analytic methods, where L is N-butylbenzimidazole and bipy is 2,2′-bipyridine. Single crystals of [Cu(L)(bipy)](ClO₄)₂ suitable for X-ray diffraction study were obtained by slow diffusion of diethyl ether into a DMF solution of the complex and the complex was found to crystallize as [Cu(L)(bipy)](ClO₄)₂·DMF. The asymmetric unit contains one [Cu(L)(bipy)]²⁺, two uncoordinated perchlorates, and one DMF solvate. Coordination geometry around Cu(II) is distorted square pyramidal with τ value of 0.31. Thermal properties of the complexes were examined by thermogravimetric analysis, indicating that the complexes are thermally stable to 310?°C. The metal complexes were screened for their in vitro antibacterial and antifungal activities Bacillus subtilis and Bacillus cereus (as Gram(+) bacteria), Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae (as Gram(–) bacteria), and Saccharomyces cerevisiae, Candida utilis, and Candida albicans (as yeasts). The complexes show antibacterial and antifungal activities against bacteria and yeasts.     

Synthesis and Reactivity of Cationic Triruthenium Clusters Derived from 2‐Methyl‐ and 4‐Methylpyrimidines: From Conventional Cyclometalated Ligands to Novel Types of N‐Heterocyclic Carbenes

The methylation of the uncoordinated nitrogen atom of the cyclometalated triruthenium cluster complexes [Ru₃(μ‐H)(μ‐κ²N¹,C⁶‐2‐Mepyr)(CO)₁₀] ( 1 ; 2‐MepyrH=2‐methylpyrimidine) and [Ru₃(μ‐H)(μ‐κ²N¹,C⁶‐4‐Mepyr)(CO)₁₀] ( 9 ; 4‐MepyrH=4‐methylpyrimidine) gives two similar cationic complexes, [Ru₃(μ‐H)(μ‐κ²N¹,C⁶‐2,3‐Me₂pyr)(CO)₁₀]⁺( 2 ⁺) and [Ru₃(μ‐H)(μ‐κ²N¹,C⁶‐3,4‐Me₂pyr)(CO)₁₀]⁺ ( 9 ⁺), respectively, whose heterocyclic ligands belong to a novel type of N‐heterocyclic carbenes (NHCs) that have the C_carbene atom in 6‐position of a pyrimidine framework. The position of the C‐methyl group in the ligands of complexes 2 ⁺ (on C²) and 9 ⁺ (on C⁴) is of key importance for the outcome of their reactions with K[N(SiMe₃)₂], K‐selectride, and cobaltocene. Although these reagents react with 2 ⁺ to give [Ru₃(μ‐H)(μ‐κ²N¹,C⁶‐2‐CH₂‐3‐Mepyr)(CO)₁₀] ( 3 ; deprotonation of the C²‐Me group), [Ru₃(μ‐H)(μ₃‐κ³N¹,C⁵,C⁶‐4‐H‐2,3‐Me₂pyr)(CO)₉] ( 4 ; hydride addition at C⁴), and [Ru₆(μ‐H)₂{μ₆‐κ⁶N¹,N^1′,C⁵,C^5′,C⁶,C^6′‐4,4′‐bis(2,3‐Me₂pyr)}(CO)₁₈] ( 5 ; reductive dimerization at C⁴), respectively, similar reactions with 9 ⁺ have only allowed the isolation of [Ru₃(μ‐H)(μ₃‐κ²N¹,C⁶‐2‐H‐3,4‐Me₂pyr)(CO)₉] ( 11 ; hydride addition at C²). Compounds 3 and 11 also contain novel six‐membered ring NHC ligands. Theoretical studies have established that the deprotonation of 2 ⁺ and 9 ⁺ (that have ligand‐based LUMOs) are charge‐controlled processes and that both the composition of the LUMOs of these cationic complexes and the steric protection of their ligand ring atoms govern the regioselectivity of their nucleophilic addition and reduction reactions.     

Syntheses and structures of cobalt(II), nickel(II), and copper(II) complexes with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides (O-daap) containing nitrate as the counter ion

Reactions of M(NO₃)₂?·?xH₂O [M?=?Co(II), Ni(II), and Cu(II)] with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides(O-daap) in CH₃CN yield [Co(O-dmap)(NO₃)₂] (1), [Co(O-deap)(NO₃)₂] (2), [Co(O-dpap)(NO₃)₂] (3), [Ni(O-dmap)(H₂O)₃](NO₃)₂] (4), [Ni(O-deap)(H₂O)₂(NO₃)](NO₃)] (5), [Cu(O-deap)(NO₃)₂] (6), and [Cu(O-dpap)(NO₃)₂] (7). X-ray crystal structures of 1, 2, 4, 5, and 7 reveal that O-daap ligands coordinate tridentate to each metal, O–N–O, with nitrate playing a vital role in molecular and crystal structures of all the complexes. The coordination geometry in the two Co(II) complexes, 1 and 2, is approximately pentagonal bipyramidal with nitrate bonded in a slightly unsymmetrical bidentate chelating mode. [Ni(dmap)(H₂O)₃](NO₃)₂ (4) and [Ni(deap)(H₂O)₂(NO₃)](NO₃) (5) exhibit octahedral geometry, the former containing uncoordinated nitrate while the latter has one nitrate coordinated unidentate and the other nitrate outside the coordination sphere. The Cu(II) in [Cu(dpap)(NO₃)₂] (7) occupies a distorted square pyramidal geometry and is linked to two unidentate nitrates, although one nitrate is also involved in a weak interaction with the metal through its other oxygen. IR spectra and other physical studies are consistent with their crystal structural data. O-dmap?=?N,N,N′,N′-tetramethylpyridine-2,6-dicarboxamides; O-deap?=?N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamides; and O-dpap?=?N,N,N′,N′-tetraisopropylpyridine-2,6-dicarboxamides.     

Phosphoester binding,DNA binding,DNA cleavage and in vitro cytotoxicity studies of simple heteroleptic copper(II) complexes with bidentate ligands

Abstract

Two mononuclear heteroleptic copper complexes, [Cu(±trans-dach)(bpy)](ClO₄)₂ 1a and [Cu(±trans-dach)(phen)](ClO₄)₂ 2a [dach?=?1,2-diaminocyclohexane, bpy?=?2,2′-bipyridine and phen?=?1,10-phenanthroline], were synthesized and analyzed by CHN analysis, electronic absorption, FT-IR spectroscopy, EPR, and SXRD. The molecular structures of 1a and 2a showed octahedral geometry around Cu(II). Both complexes interacted with phosphoesters and DNA. Their binding affinities with diphenylphosphate, di n-butylphosphate, trimethylphosphate, and triphenylphosphate were studied by UV–vis spectroscopy. For understanding the stereochemical role of dach ligand toward DNA interaction, enantiopure DACH complexes [Cu(R,R-trans-dach(bpy)](ClO₄)₂ 1b, [Cu(S,S-trans-dach)(bpy)](ClO₄)₂ 1c, [Cu(cis-dach)(bpy)](ClO₄)₂ 1d, [Cu(R,R-trans-dach)(phen)](ClO₄)₂ 2b, [Cu(S,S-trans-dach)(phen)](ClO₄)₂ 2c, and [Cu(cis-dach)(phen)](ClO₄)₂ 2d were synthesized and analyzed. All complexes interacted with calf thymus-DNA (CT-DNA) as studied by UV–vis spectroscopy. The nature of binding to CT-DNA was groove/electrostatic as supported by circular dichroism, cyclic voltammetry, and docking studies. Complexes were able to cleave plasmid DNA at 12.5 µM (1a–d) and 6 µM (2a–d), where 2d showed 64% Form II and 36% Form III. The in vitro cytotoxic studies of two different cancer cell lines showed inhibition with low IC₅₀ value in comparison to reference control (cisplatin). These complexes are efficient in inducing apoptosis in cancer cells, making them viable for potent anticancer activity.     

Syntheses and Crystal Structures of Cadmium Complexes with Thiophenedicarboxylate and Bipyridine‐like Ligands

Two new coordination polymers [Cd(tdc)(bpy)(H₂O)]_n ( 1 ) and [Cd(tdc)(phen)]_n ( 2 ) (H₂tdc = thiophene‐2,5‐dicarboxylic acid, bpy = 2,2′‐bipyridine and phen = 1,10‐phenanthroline) have been synthesized under hydrothermal condition. Their crystal structures have been established by X‐ray single‐crystal diffraction. Complex 1 crystallizes in the orthorhombic space group Fdd2 with a = 14.757(7), b = 45.38(2), c = 10.518(5) Å, V = 7044(6) ų, Z = 16; 2 in the monoclinic space group P2₁/c with a = 7.262(1), b = 21.970(2), c = 10.051(1) Å, β = 105.01(1)°, V = 1548.8(2) ų, Z = 4. Both of them are double‐stranded chains and further assembled into three‐dimensional networks by π‐π stacking interactions. 1 and 2 are stable in air, and show blue photoluminescence at 415 nm and 410 nm, respectively.     

Synthesis,characterization, and antibacterial activities of two new copper(II) glycinate complexes incorporating 2-(4′-thiazolyl)benzimidazole/2-(2-pyridyl)benzimidazole

Two new complexes, [Cu(TBZ)(Gly)(H₂O)]Cl (1) and [Cu(HPB)(Gly)Cl]?·?2H₂O (2) (TBZ?=?2-(4′-thiazolyl)benzimidazole, HPB?=?2-(2-pyridyl)benzimidazole, and Gly?=?glycinate), have been synthesized and characterized by elemental analysis, molar conductivity, UV-Vis, and IR methods. The complexes, structurally characterized by single-crystal X-ray crystallography, show a slightly distorted square-pyramidal coordination geometry in which two nitrogen atoms of TBZ or HPB and the carboxylate oxygen and amino nitrogen of glycinate bind in the plane and a water or chloride coordinated at the axial site. The complexes, free ligands, and copper(II) chloride were tested for their ability to inhibit growth of Bacillus subtilis, Staphylococcus aureus, and Salmonella. The results show that the complexes have good antibacterial activities against the microorganisms compared with their ligands and copper(II) chloride.     

Crystal Structures of the Europium and Yttrium Hydroxychromates Eu(OH)(CrO4) and Y(OH)(CrO4); Structural Evolution as a Function of the Ln3+ Ionic Radius

The compounds Eu(OH)(CrO₄) and Y(OH)(CrO₄) were obtained under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction analysis. They are isostructural and crystallize in the monoclinic system, space group P2₁/n (no. 14) with lattice parameters a = 8.278(1) Å, b = 11.400(2) Å, c = 8.393(1) Å, β = 93.76(2)°, V = 790.3(2) Å³, Z = 4, d = 4.79 g · cm^–3 for Eu(OH)(CrO₄) and a = 8.151(1) Å, b = 11.362(2) Å, c = 8.285(1) Å, β = 94.23(1)°, V = 765.2(2) Å³, Z = 4, d = 3.85 g · cm^–3 for Y(OH)(CrO₄). The [EuO₈] polyhedra form infinite double chains along the a direction, which are connected by common edges and corners. These double chains are related together in the two other directions by the [CrO₄]^2– tetrahedra to form a three‐dimensional network in which channels appear parallel to the [100] direction. We examine the structural evolution, as a function of the Ln³⁺ ionic radius, in the series Ln(OH)(CrO₄) compounds (with Ln = Nd, Eu, Gd, Tb, Er, Yb) and Y(OH)(CrO₄). To determine the best coordination number of each lanthanide and yttrium ions, different calculations of bond valence sum were realized.     

Gold(III) amine complexes in aqueous alkali solutions

The gold(III) 1,3-diaminopropane complex [Au(1,3-pn)(1,3-pn-H)]Cl₂ has been synthesized. Its dissociation constant has been determined: Au(1,3-pn)₂³⁺ = Au(1,3-pn-H)²⁺ + H⁺, logK _a1 = −7.03 ± 0.05 (I = 0.1 mol/L NaClO₄). Considerable spectral changes are observed for strong alkali solutions (pH 11–14) containing the monoamido forms of the gold(III) ethylenediamine, 1,3-diaminopropane, and diethylenetriamine complexes (Au(en)(en-H)²⁺, Au(1,3-pn)(1,3-pn-H)²⁺, Au(dien-H)OH⁺). These changes are attributed to the formation of the diamido species Au(en-H)₂⁺, Au(1,3-pn-H)₂⁺, and Au(dien-2H)OH⁰. The dissociation constants of the monoamido complexes have been determined: Au(en)(en-H)²⁺ (logK _a2 = −10.9 ± 0.1 at I = 0.001–0.01 mol/L NaCl); Au(1,3-pn)(1,3-pn-H)²⁺ (logK _a2 = −11.3 ± 0.1 at I = 0.1 mol/L NaCl); Au(dien-H)OH⁺ (logK _a2 = −12.4 ± 0.1 at I = 0.1 mol/L NaCl).     

Mixed pseudohalide complexes of copper(II). Crystal and molecular structure of [Cu(N3)(NCS)(tmen)] n and of [Cu(N3)(NCO)(tmen)]2 (tmen = N,N,N′,N′-tetramethylethylenediamine)

The compounds [Cu(N₃)(NSC)(tmen)]_n (1), [Cu(N₃)(NCO)(tmen)]_n (2) and [Cu(N₃)(NCO)(tmen)]₂ (3) (tmen=N,N,N′,N′-tetramethylethylenediamine) were synthesized and studied by i.r. spectroscopy. Single crystals of compounds (1) and (3) were obtained and characterized by X-ray diffraction. The structure of compound (1) consists of neutral chains of copper(II) ions bridged by a single azido ligand showing the asymmetric end-to-end coordination fashion. Each copper ion is also surrounded by the other three nitrogen atoms; two from one N,N,N′,N′-tetramethylethylenediamine and one from a terminal bonded thiocyanate group. Compound (2) decomposes slowly in acetone and the product formed [Cu(N₃)(NCO)(tmen)]₂ (3) crystallizes in the monoclinic system (P2₁). The structure of (3) consists of dimeric units in which the Cu atoms are penta-coordinated and connected by μ(1,3) bridging azido and cyanate ligands. In both cases the five coordinated atoms give rise to a slightly distorted square-based pyramid coordination geometry at each copper ion. The thermal behavior of [Cu(N₃)(NSC)(tmen)]_n (1) and [Cu(N₃)(NCO)(tmen)]_n (2) were investigated and the final decomposition products were identified by X-ray powder diagrams.     

Ternary copper(II) complex of 1,10-phenanthroline and L-glycine: crystal structure and interaction with DNA

A ternary copper(II) complex, [Cu(phen)(L-Gly)(H₂O)] ·?NO₃ ·?1.5H₂O (phen =?1,10-phenanthroline, L-Gly =?L-glycine), has been synthesized and structurally characterized. The complex crystallized in a monoclinic system with space group C2/c, a =?20.572(3) Å, b =?6.9987(10) Å, c =?23.561(3) Å, β?= 98.776(5)°. The five-coordinate copper(II) center is a distorted square pyramid. Absorption spectra, fluorescence spectra and viscosity measurements showed interaction between the copper complex and DNA through an intercalative mode. The complex exhibited efficient DNA cleavage activity at micromolar concentration in the presence of ascorbate with hydroxyl radicals as the active species.     

Hydrogen‐transfer reduction of α,β‐unsaturated carbonyl compounds catalyzed by naphthyridine‐functionalized N‐heterocyclic carbene complexes

Substitution of silver complex of 2‐chloro‐7‐(mesitylimidazolylidenylmethyl)naphthyridine (NpNHC) with palladium(II), rhodium(I) and iridium(I) metal precursors provided [Pd(C ,N ‐NpNHC)(η³‐allyl)](BF₄) ( 5 ), RhCl(COD)(C ‐NpNHC) ( 6a ) and IrCl(COD)(C ‐NpNHC) ( 6b ), respectively. Abstraction of chloride from 6a and 6b with AgBF₄ provided the chelation complexes [Rh(COD)(C ,N ‐NpNHC)](BF₄) ( 7a ) and Ir(COD)(C ,N ‐NpNHC)(BF₄) ( 7b ), respectively. All complexes were characterized using NMR and elemental analyses and the structural details of 5 and 6a were further confirmed using X‐ray crystallography. In catalytic activity studies, complex 5 was found to be an effective catalyst in the hydrogen‐transfer reduction of α,β‐unsaturated carbonyl compounds into the corresponding saturated carbonyl compounds.     

Synthesis,Characterization and Crystal Structure of a Ternary Cu(II) Complex with 1,10-Phenanthroline and l-Leucinate

The complex [Cu(l-Leu)(phen)(H₂O)]NO₃ has been synthesized and characterized by elemental analysis, molar conductivity, spectroscopic and X-ray diffraction methods, where phen = 1,10-phenanthroline and l-Leu = l-leucinate. The complex crystallizes in the triclinic space group Pī with two molecules in a unit cell of dimensions a = 7.288(4) Å, b = 11.588(7) Å, c = 12.349(3) Å, α = 86.388(10)^o, β = 76.175(11)°, γ = 72.132(3)°, V = 963.8(10) ų, Z = 2, D _c = 1.564 g/cm³, μ = 1.177 mm^?1, F(000) = 470, R ₁ = 0.0611, and wR ₂ = 0.0711. The copper(II) is ligated in a distorted square-pyramidal geometry by the two nitrogen atoms of phen and the amino nitrogen atom and one carboxylate oxygen atom from each independent l-Leu moiety in the basal plane, and one water oxygen at the apical position. A supramolecular configuration is formed from strong phen-phen stacking interactions between neighboring [Cu(l-leu)(phen)(H₂O)]⁺cations in the crystal.     

Ethylenediamine-N,N"-Diacetate Ion (Edda2–) as a Tridentate Ligand: Synthesis and Structure of the [Co(Edda)(Dien)]ClO4 · H2O and [Co(Edda)(En)(CN)] · 2H2O Complexes

The cobalt(III) complexes with tridentate ethylenediamine-N,N"-diacetate ions (Edda^2–) and additional ligands, namely, diethylenetriamine (Dien) or ethylenediamine (En) and cyanide ions, were synthesized. As follows from X-ray diffraction analysis of [Co(Edda)(Dien)]ClO₄· H₂O (monoclinic crystals with a = 9.243 (2) Å, b = 14.167 (4) Å, c = 13.046 (3) Å, = 91.19 (2)°, Z = 4, space group P2₁/c), the secondary N atom of the Dien ligand occupies the trans-position relative to the N atom of the Edda^2– ligand, which contains a free acetate group. Two fac-isomers of [Co(Edda)(En)(CN)] with the CN^– ion in the cis- and trans-positions relative to the oxygen atom of the carboxyl group were isolated, and the structure of the trans-(O,CN)-[Co(Edda)(En)(CN)]· 2H₂O was determined: monoclinic crystals with a = 9.136 (3) Å, b = 15.484 (3) Å, c = 10.564 (3) Å, = 110.67 (5)°, Z = 4, space group P2₁/c.