Oxidative addition reaction of o-quinones to triphenylantimony: novel triphenylantimony catecholate complexes

New catecholate Sb(V) complexes triphenyl(3,6-di-tert-butylcatecholato)antimony(V) Ph₃Sb(3,6-DBCat) (1) and triphenyl(perchloroxanthrenecatecholato)antimony(V) Ph₃Sb(^OXCat_Cl) (2) were synthesized by the oxidative addition reaction of corresponding o-quinones (3,6-di-tert-butyl-o-benzoquinone and perchloroxanthrenequinone-2,3) with triphenylantimony. Catecholates 1 and 2 can alternatively be synthesized by reacting the appropriate thallium catecholate with triphenylantimony dichloride. The oxidative addition reaction of an equimolar ratio of 4,4′-di-(3-methyl-6-tert-butyl-o-benzoquinone) and triphenylantimony yielded 4-(2-methyl-5-tert-butyl-cyclohexadien-1,5-dion-3,4-yl)-(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V) Ph₃Sb(Cat-Q) (3); in the case of a 1:2 molar ratio, complex 4,4′-di-[(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V)] Ph₃Sb(Cat-Cat)SbPh₃ (4) resulted. Complexes 1-4 were characterized by IR- and ¹H NMR spectroscopy. Molecular structures of 1, 2 and 4 were determined by X-ray crystallography to be a distorted tetragonal-pyramidal.     

Antiradical activity of morpholine- and piperazine-functionalized triphenylantimony(V) catecholates

The antiradical activity of the functionalized triphenylantimony(V) catecholates Ph₃Sb[4-O(CH₂CH₂)₂N-3,6-DBCat] (I), Ph₃Sb[4,5-Piperaz-3,6-DBCat] (II), and Ph₃Sb[4-PhN(CH₂CH₂)₂N-3,6-DBCat] (III) (where [4-O(CH₂CH₂)₂N-3,6-DBCat]^2?, [4,5-Piperaz-3,6-DBCat]^2?, and [4-PhN(CH₂CH₂)₂N-3,6-DBCat]^2? are the dianionic ligands 3,6-di-tert-butyl-4-(morpholin-1-yl)-, 3,6-di-tert-butyl-4,5-(piperazine-1,4-diyl)-, and 3,6-di-tert-butyl-4-(4-phenylpiperazin-1-yl)catecholates, respectively) was studied in reactions with the diphenylpicrylhydrazyl radical during autooxidation of unsaturated fatty (oleic and linoleic) acids with lipid peroxidation of Russian sturgeon (Acipenser gueldenstaedti B.) sperm and human blood erythrocytes in vitro as examples. The EC₅₀ and n _DPPH values obtained indicate the high antiradical activity of complexes II and III in the reactions with the stable radical. On the whole, complexes I–III inhibit the lipid peroxidation in both model (oxidation of unsaturated fatty acids) and in vitro experiments. The inhibiting effects of the complexes are comparable with and even, in some cases, higher than those of the known antioxidant ionol.     

Tri- and tetraphenylantimony propiolates: Syntheses and structures

The reaction of triphenylantimony with propiolic acid in the presence of hydrogen peroxide (molar ratios 1 : 2 : 1 and 1 : 1 : 1) in diethyl ether affords triphenylantimony dipropiolate Ph₃Sb[OC(O)C≡CH]₂ (I) and μ₂-oxobis[(propiolato)triphenylantimony] [Ph₃SbOC(O)C≡CH]₂O (II). Tetraphenylantimony propiolate Ph₄SbOC(O)C≡CH (III) is synthesized from pentaphenylantimony and propiolic or acetylenedicarboxylic acid in toluene. According to the X-ray diffraction data, the crystals of compounds I and III include two types of crystallographically independent molecules (a and b). The antimony atoms in molecules Ia, Ib, II, IIIa, and IIIb have the trigonal-bipyramidal coordination mode with different degrees of distortion. The OSbO and OSbC axial angles are 176.8(2)° (Ia, Ib), 170.17(15)°, 178.78(14)° (II), and 173.2(5)°, 174.4(5)° (IIIa, IIIb). The CSbC equatorial angles lie in the ranges 108.2(3)°–143.1(3)° (I), 109.0(2)°–131.0(2)° (II), and 113.1(4)°–125.4(4)° (III). The SbOSb angle in II is 141.55(19)°. The Sb-C bond lengths are 2.103(8)–2.141(5) (I), 2.105(5)–2.119(5) (II), and 2.076(12)–2.166(13) Å (III). The Sb-O distances increase in a series of I, II, and III: 2.139(6)–2.156(7) (Ia, Ib); 2.206(4), 2.218(3) (II); and 2.338(10), 2.340(10) Å (III).     

Penta- and hexacoordinate antimony(V) compounds with the tridentate O,N,O-donor ligand: Electrochemical transformations and antiradical activity

The electrochemical transformations and antiradical activity of penta- and hexacoordinate antimony(V) complexes I–V containing the tridentate O,N,O-donor ligand, N,N-bis(di-3,5-tert-butyl-2-hydroxyphenyl)amine, are studied. The oxidation of hexacoordinate triarylantimony(V) compounds R₃Sb(Cat-NH-Cat) (I–III) leads to the formation of neutral paramagnetic intermediates Ia–IIIa. Two anodic reversible one-electron stages are observed for pentacoordinate complexes R′₂Sb(Cat-N-Cat) (IV, V). The possibility of the formation of stable paramagnetic species in electrochemical oxidation is a reason for the antiradical activity of the complexes. The study of the reactions of compounds I–V with the electrogenerated superoxide radical anion, diphenylpicrylhydrazyl radical, peroxy radicals, and hydroperoxides formed by the autooxidation of unsaturated fatty acids (oleic, linoleic) shows that all complexes exhibit a pronounced antiradical activity. The highest effect is observed for compounds I, IV, and V characterized by the prolonged action.     

New morpholine- and piperazine-functionalized triphenylantimony(V) catecholates: The spectroscopic and electrochemical studies

Novel functionalized triphenylantimony(V) catecholates - Ph₃Sb[4-O(CH₂CH₂)₂N-3,6-DBCat] (1), Ph₃Sb[4-PhN(CH₂CH₂)₂N-3,6-DBCat] (2), Ph₃Sb[4-Ph₂CHN(CH₂CH₂)₂N-3,6-DBCat] (3), Ph₃Sb[4,5-Piperaz-3,6-DBCat] (4) and binuclear bis-catecholate Ph₃Sb[3,6-DBCat-4-N(CH₂CH₂)₂N-4-3,6-DBCat]SbPh₃ (5) were synthesized by the oxidative addition reaction of corresponding o-quinones with triphenylantimony. The [4-O(CH₂CH₂)₂N-3,6-DBCat]²⁻, [4-PhN(CH₂CH₂)₂N-3,6-DBCat]²⁻, [4-Ph₂CHN(CH₂CH₂)₂N-3,6-DBCat]²⁻ and [4,5-Piperaz-3,6-DBCat]²⁻ are 4-(morpholin-1-yl)-, 4-(4-phenyl-piperazin-1-yl)-, 4-(4-dephenylmethyl-piperazin-1-yl)-, and 4,5-(piperazin-1,4-diyl)-3,6-di-tert-butyl-catecholate dianionic ligands, correspondingly. Complexes 1-5 were characterized in details by IR-, ¹H and ¹³C NMR spectroscopy and cyclic voltammometry. Molecular structure of 4·CH₃OH was determined by X-ray crystallography to be a distorted tetragonal-pyramidal. The NMR spectroscopic and electrochemical investigations of complexes in the presence of air reveal the reactions of complexes with dioxygen leading to the formation of spiroendoperoxides of 1,2,4,3-trioxastibolane type in a NMR yield of 25-37%.     

Radical scavenging activity of sterically hindered catecholate and o-amidophenolate complexes of LSbPh3 type

The radical scavenging effect of the substituted catecholates (1-3, 6) and o-amidophenolates (4, 5) of triphenylantimony(V) in reactions with DPPH^• radical and in a process of oleic acid peroxidation was studied in details. Complexes 1-6 show the high activity in radical scavenging reactions with DPPH^• radical leading to disappearance of radical species. Complexes were demonstrated to be high-efficient inhibitors of chain-radical process of the peroxidation of oleic acid as well as the effective destructors of the formed hydroperoxides. It was found that the effectiveness of complexes studied in the inhibition of the peroxidation of oleic acid depends on the first oxidation potential of complex.     

X-ray single crystal, spectral, thermal analysis and 31P{1H} NMR of ruthenium(II)/ether-phosphine/1,2-diphenyl-1,2-ethanediamine complexes

Neutral complex 1 and mono-cationic complex 2 were made available using Ph₂PCH₂CH₂OCH₃ and 1,2-diphenyl-1,2-ethanediamine ligands. One of the chloride atoms in complex 1 was abstracted by AgOTf to prepare the mono-cationic O–Ru–P closed complex 2. The hemilability of hybrid ether-phosphine ligand in such complexes was monitored by ³¹P{¹H} NMR and confirmed by X-ray single crystal. XRD structure of complex 2 was found to be a Trigonal crystal system with P3 space group and Z = 6.     

Redox reactions involving the indium(III) catecholate complexes

Indium catecholate complexes 3,6-CatInR (3,6-Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion (3,6-Q), R = Me (I) and Et (II)) are synthesized by the exchange reaction between RInI₂ and thallium catecholate 3,6-CatTl₂. Compounds I and II are trimeric in both the solution and crystalline state. The oxidation of compound I and earlier described complex [3,6-CatInI(THF)]₂ (THF is tetrahydrofuran) by various substrates (iodine, 3,6-Q, and tetramethylthiuram disulfide) is studied. Different indium(III) o-semiquinone complexes are the reaction products, depending on the reaction conditions.     

Synthesis and structure of antimony iodide complexes: [Ph3MeP] + 2 [SbI5]2−, [Ph3MeP] + 3 [Sb3I12]3−·Me2C=O, [Ph3MeP] + 3 [Sb3I12]3−, and [Ph3MeP] + 3 [Sb2I9]3−

Complexes with antimony-containing anions, [Ph₃MeP] ₊ ² [SbI₅]^2? (I), [Ph₃MeP] ₊ ² [Sb₃I₁₂]^3? (II), [Ph₃MeP] ₊ ³ [Sb₃I₁₂]^3? · Me₂C=O (III), and [Ph₃MeP] ₊ ³ [Sb₂I₉]^3? (IV), were synthesized by reacting triphenylmethylphosphonium iodide with antimony iodide. The central atom in the cations of the complexes has a distorted tetrahedral coordination. In the trinuclear anions of complexes II and III, each of the terminal SbI₃ groups is bound to the central Sb atom through two μ₂- and one μ₃ iodine bridges (SbSbSb angles are 103.0° and 102.2°, respectively). In the binuclear anion of complex IV, antimony atoms are linked with each other via three bridging iodine atoms.     

Synthesis and structures of mercury and cadmium complexes: [Ph4Sb] 2 + [Hg2I6]2−·Ph2Hg, [Ph4Sb] 2 + [E2I6]2− (E = Hg, Cd), and [Ph4Sb] 2 + [Hg4I10]2−

The reaction of pentaphenylantimony with mercury iodide affords the ionic complex [Ph₄Sb] ₂ ⁺ [Hg₂I₆]^2?·Ph₂Hg (I). The [Ph₄Sb] ₂ ⁺ [Hg₂I₆]^2? (II) and [Ph₄Sb] ₂ ⁺ [Cd₂I₆]^2? (III) complexes are synthesized from tetraphenylantimony iodide and mercury and cadmium iodides. The [Ph₄Sb] ₂ ⁺ [Hg₄I₁₀]^2? complex (IV) is prepared from tetraphenylantimony 2,4-dimethylbenzenesulfonate and mercury iodide. According to the X-ray diffraction data, the Sb atom in the [Ph₄Sb]⁺ cations of complex I has virtually ideal tetrahedral coordination (the CSbC angles are 108.09°–109.64°). In the central square fragment Hg₂I₂ of the [Hg₂I₆]^2? anion, the Hg-I_br bond lengths are 2.825 and 3.075 Å, and the terminal iodine atoms are more strongly bonded to the mercury atoms (Hg-I_term 2.691 and 2.700 Å). The [Cd₂I₆]^2? anion in complex III has a similar structure (the Cd-I_bridg and Cd-I_term distances are 2.865, 2.872 and 2.723, 2.748 Å, respectively). The anions in complex IV are joined by I…Hg (3.651 Å) and I…I (4.058 Å) interactions into an infinite dimeric network.     

Trialkylantimony(V) o-amidophenolates: Electrochemical transformations and antiradical activity

The electrochemical transformations and antiradical activity of trialkylantimony(V) o-amidophenolate derivatives, (AP)SbR₃ (AP = 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-amidophenolate); R = CH₃ (I), C₂H₅ (II), and C₆H₁₁ (III), are studied. The electrochemical oxidation of compounds I–III proceeds successively to form mono- and dicationic forms of the complexes. The presence of the donor hydrocarbon groups at the antimony(V) atom shifts the oxidation potentials to the cathodic range and decreases the stability of the monocationic complexes formed in electrochemical oxidation. The second anodic process is irreversible and accompanied by o-iminoquinone decoordination. The antiradical activity of compounds I–III is studied in the reaction with the diphenylpicrylhydrazyl radical and oleic acid autooxidation. The values obtained for indices EC₅₀ and IC₅₀ indicate the antiradical activity of the studied compounds. Complexes I–III were found to be the efficient inhibitors of oleic acid oxidation and act as efficient destructors of hydroperoxides.     

Evaluation of catalytic activity of imidazolo[1,2-a]pyridine derivatives: oxidation of catechol

A series of heterocyclic compounds possessing imidazolo[1,2-a]pyridine moiety, namely, ethyl 7-methylimidazolo[1,2-a] pyridine-2-carboxylate L1; 2-(3-nitrophenyl)imidazo[1,2-a]pyridine L2; 3-(imidazo[1,2-a]pyridine-2-yl)aniline L3; 2-phenylimidazolo[1,2-a]pyridine-3carbaldehyde L4; and 2-phenylimidazo[1,2-a]pyridine L5 were synthesized. The in situ generated copper (II), iron (II), and zinc (II) complexes of these compounds (L1–L5) were examined for their catalytic activities and were found to be effective catalysts for the oxidation of catechol to o-quinone with the atmospheric oxygen. The present study reveals that the rate of oxidation depends on four parameters: the nature of the ligand, transition metals, ion salts, and the concentration of the complex. The combination L2(Cu(CH ₃ COO) ₂ ) gives the highest rate.     

Synthesis and molecular structures of cymantrenecarboxylate derivatives of titanium(IV) and vanadium(III) cyclopentadienyl complexes and of copper(II) and manganese(II) lutidine complexes

The reactions of dimethyltitanocene borohydride and vanadocene with cymantrenecarboxylic acid CymCOOH gave the monomer (C₅H₄Me)₂Ti(OOCCym)₂ (I) and dimer (C₅H₅)V(OOCCym)₄V(C₅H₅) (II), respectively. Treatment of Cu(II) cymantrenylcarboxylate with excess lutidine gives the monomer (C₇H₉N)₂Cu(COOCym)₂ (III). The reaction of lutidine with a mixture of Cu(II) and Mn(II) bis-cymantrenecarboxylates affords the heterometallic trinuclear complex (C₇H₉N)Cu(OOCCym)₃Mn(OOCCym)₃Cu(C₇H₉N) (IV). The structures of I–IV were established by X-ray diffraction. In I and III, the cymantrenecarboxylate groups are terminal and in II and IV, they are bridging, which is also manifested as characteristic OCO stretching bands in the IR spectra.     

Syntheses, structures and intermolecular interactions of tetraorganoammonium, -phosphonium and -stibonium dimethyl- and diphenyltetrahaloantimonates

The syntheses and spectroscopic (NMR, MS) investigations of the antimonates [Ph₄P]⁺[Me₂SbCl₄]⁻ (1), [Me₄Sb]⁺[Me₂SbCl₄]⁻ (2), [Et₄N]⁺[Ph₂SbCl₄]⁻ (3), [Bu₄N]⁺[Ph₂SbCl₄]⁻ (4), [Me₄Sb]⁺[Ph₂SbCl₄]⁻ (5), [Et₃MeSb]⁺[Ph₂SbCl₄]⁻ (6), [Et₄N]⁺[Ph₂SbF₄]⁻ (7) and [Et₄N]⁺[Ph₂SbBr₄]⁻ (8) are reported. Halogen scrambling reactions of Et₄NBr or Ph₄EBr (E = P, Sb) with R₂SbCl₃ (R = Me, Ph) produce mixtures of compounds from which crystals of [Et₄N]⁺[Ph₂SbBr_1.24Cl_2.76]⁻ (9), [Et₄N]⁺[Ph₂SbBr_2.92Cl_1.08]⁻ (10) or [Ph₄Sb]⁺[Me₂SbCl₄]⁻ (11) were isolated. The crystal and molecular structures of 1 and 3-11 are reported.     

Synthesis and catalytic activity of novel Ni-N complexes

A series of nickel complexes with 1,3-xylylenediamine, 1,2-diaminobenzene and 1,2-aminobenzylamine were first synthesized and characterized. The reaction of these amines with Ni(OAc)₂ · 4H₂O and NiCl₂ · 6H₂O in methanol or tetrahydrofuran resulted in the production of four novel nickel complexes I, II, III, and IV. The structure of each complex was determined by X-ray diffraction analysis. Each complex was also characterized using elemental analysis, ¹H NMR and IR. The complexes were then used to catalyze the Henry reaction, and good catalytic results (65?C99%) were achieved. The catalytic activity of the complexes was determined by ¹H NMR.     

Diphenyldichalcogenide complexes of iron, chromium and rhenium carbonyls

The substitution of a labile THF ligand in Cr(CO)₅(THF) by the Ph₂Se₂ molecule provided the monomeric complex Cr(CO)₅(Ph₂Se₂) (I). The similar diiodo-tricarbonyl-iron complex (CO)₃FeI₂(Ph₂Se₂) (II) (along with [(CO)₃Fe(??-SePh)₃Fe(CO)₃]⁺(I₅)^? (III) as a by-product) was separated upon the treatment of ??phenylselenyl iodide?? [PhSeI] with iron pentacarbonyl, Fe(CO)₅. Complex II is isostructural with the known tellurium-containing analogue, (CO)₃FeI₂(Te₂Ph₂). The latter have provided the dimeric tellurophenyl bridged iodo-tricarbonyl-iron complex [(CO)₃IFe(??-TePh)]₂ (IV) under action of the excess of Fe(CO)₅. Its bromide analogue [(CO)₃BrFe(??-TePh)]₂ (V) was prepared upon the treatment of PhTeBr with the excess of Fe(CO)₅. The reaction of [PhSeI] with Re(CO)₅Cl afforded only [(CO)₆Re₂(??-I)₂(??-Se₂Ph₂)] (VI) in contrast to the (CO)₃Re(PhTeI)₃(??₃-I) formation in similar known reaction of [PhTeI]. The molecular and crystal structures of I?CVI is discussed.     

Synthesis and structure of Bis(tetraphenylantimony) 1,2-diphenylethanedione dioximate toluene solvate Ph4SbONC(Ph)C(Ph)ONSbPh4 · 2PhCH3 and tetraphenylantimony 2-hydroxy-1,2-diphenylethanone oximate Ph4SbONC(Ph)CH(Ph)OH

Bis(tetraphenylantimony) 1,2-diphenylethanedione dioximate toluene solvate Ph₄SbONC(Ph)C(Ph)NOSbPh₄ · 2 PhCH₃ (I) and tetraphenylantimony 2-hydroxy-1,2-diphenyl(ethanone oximate Ph₄SbONC(Ph)CH(Ph)OH (II) have been synthesized by the reaction of pentaphenylantimony with 1,2-diphenylethane dioxime and 2-hydroxy-1,2-diphenylethanone oxime in toluene. A molecule of compound I is centrosymmetric with an inversion center at the midpoint of the C-C bond in the ethane moiety. A crystal of compound II contains two types of crystallographically independent molecules A and B. Antimony atoms in compounds I and II have a distorted tetragonal bipyramidal surrounding: equatorial CSbC and axial CSbO angles are 114.95(10)°–126.82(11)° and 173.24(9)° (I), 117.2(2)°–122.9(2)° and 178.15(18)° (IIA), and 112.3(2)°–127.7(2)° and 175.09(18)° (IIB), respectively. The Sb-C and Sb-O bond lengths are 2.106(3)–2.182(3) and 2.1344(17) ÅI), 2.118(5)–2.4199(5) and 2.153(4)Å(IIA), and 2.106(5)–2.200(5) and 2.120(4) Å (IIB), respectively. A molecule of compounds I, IIA, and IIB has been found to contain Sb...N intramolecular contacts (2.838(3), 2.867(5), and 2.889(5)Å, respectively). Molecules of compounds IIA and IIB contain O-H...N hydrogen bonds (H...N, 1.91(9) and 2.06(8) Å, respectively).     

Tin(IV) complexes based on 2-hydroxy-3,6-di-tert-butyl-para-benzoquinone: Syntheses,structures, and electrochemical behavior in solution

A series of new tin(IV) complexes based on 2-hydroxy-3,6-di-tert-butyl-para-benzoquinone (LH) of the general formula L₂SnR₂ (R = Me (I), Et (II), Bu ⁿ (III), Ph (IV)) and LSnMe₃ (V) were synthesized. The obtained compounds were characterized by IR and ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy and elemental analysis. The X-ray diffraction analysis was carried out for complexes L₂Sn(Bu ⁿ )₂ (III) and LSnMe₃ (V). The low-frequency region of the IR spectra, which has not earlier been studied in detail, was interpreted for compounds I–V and previously described complex LSnPh₃ (VI). The electrochemical properties of LH and related tin complexes I–VI were studied. The nature of the hydrocarbon groups at the metal atom affects the stability of the intermediates formed in the electrochemical reactions.     

Synthesis and structure of tetraphenylantimony and triphenylantimony 4-oxybenzoates

Solvate Ph₃Sb[OC(O)C₆H₄(OH-4)]₂ · 1/2Et₂O (I) has been synthesized by the reaction between triphenylantimony and 4-oxybenzoic acid in the presence of hydrogen peroxide in diethyl ether. Tetraphenylantimony 4-oxybenzoate, which crystallizes from DMSO in the form of solvate Ph₄SbOC(O)C₆H₄(OH-4) · DMSO (II), has been synthesized from pentaphenylantimony and triphenylantimony bis(4-oxybenzoate) or 4-oxybenzoic acid. According to X-ray diffraction data, an antimony atom in molecules of compounds I and II has a trigonal bipyramidal coordination. Crystals of compound I contain two crystallographically independent types of molecules (A and B). The Sb-C and Sb-O distances, the equatorial CSbC and axial OSbO angles are, respectively, 2.083(9)–2.103(8)Å; 2.068(5), 2.128(5)Å; 117.6(3)°–124.2(3)° and 171.5(2)° (IA); 2.103(9)–2.135(8)Å; 2.086(5), 2.154(6)Å;110.2(3)°–138.0(4)° and 174.8(2)° (IB). In compound II, Sb-C is 2.117(2)–2.175(2) Å, Sb-O is 2.247(2) Å, and C_eqSbC_eq and OSbC_ax angles are 110.89(9)°–133.30(9)° and 177.05(7)°, respectively. The Sb…O=C intramolecular contacts are 3.151(7), 3.153(8) Å (IA), 2.985(8), 3.008(9) Å (IB), and 2.975(5) Å (II). Molecules IA and IB are conformation isomers, which differ from each other by the arrangement of carboxyl groups with respect to the equatorial plane.     

Mononuclear copper(II) complexes of bis-triazole-based macrocyclic Schiff base hydrazones: direct synthesis,EPR studies,magnetic and thermal properties

Mononuclear copper(II) complexes of 1,2,4-triazole-based Schiff base macrocyclic hydrazones, III and IV, have been reported. The prepared amorphous complexes have been characterized by spectroscopic methods, electron spray ionization mass spectrometry, and elemental analysis data. Electrochemical studies of the complexes in DMSO show only one quasi-reversible reduction wave at +0.43 V (ΔE = 70 mV) and +0.42 V (ΔE = 310 mV) for III and IV, respectively, which is assigned to the Cu(II) → Cu(I) reduction process. Temperature dependence of magnetic susceptibilities of III and IV has been measured within an interval of 2–290 K. The values of χ_M at 290 K are 1.72 × 10^?3 cm³ mol^?1 and 1.71 × 10^?3 for III and IV, respectively, which increases continuously upon cooling to 2 K. EPR spectra of III and IV in frozen DMSO and DMF were also reported. The trend g_|| > g⊥ > g_e suggests the presence of an unpaired electron in the d_x2?y2 orbital of the Cu(II) in both complexes. Furthermore, spectral and antimicrobial properties of the prepared complexes were also investigated.