Syntheses,crystal structure and biological evaluation of three novel Cu (II) complexes with Schiff base derived from fluorinated amino acid and Salicylaldehyde

Three novel Cu (II) coordination complexes, formulated as [Cu₃(C₁₄H₈NO₃F) ₂ (CH₃COO)₂]_n ( 1 ), [Cu₂(C₁₄H₉NO₃F)₂(CH₃COO)Cl] ( 2 ) and [Cu(C₁₄H₈NO₃F)(CH₃OH)₂] ( 3 ), have been synthesized by 3-Fluoroanthranilic acid, Salicylaldehyde and Cu (II) salt as sources in different reaction conditions and characterized by single crystal X-ray diffraction, X-ray powder diffraction, IR spectroscopy and elemental analysis. Single-crystal diffraction analysis revealed that the complexes exhibited different coordination modes and conformations which were linked into multidimensional networks through some weak interactions. The biological activities vary greatly on account of the different Cu (II) numbers among the three complexes. In order to discuss the bioactivities, the complexes have been screened for antimicrobial activities against E. coli and S. aureus, antitumor activities against A549 (human lung cancer cells), Hela (human cervical cancer cells) and HepG-2(human liver hepatocellular carcinoma cells). Their interactions with calf thymus DNA were investigated by UV–visible and fluorescence spectrometry, as well as viscosity measurements. Interestingly, 1 (the rare 3-core Cu (II) coordination polymer) shows great antibacterial activities and highest DNA binding affinities. Antitumor studies revealed that complex 1 also exhibited highest activity.     

Synthesis, crystal structures and magnetic properties of tricyanomethanide-containing copper(II) complexes

The preparation, crystal structures and magnetic properties of the copper(II) complexes of formula [Cu(pyim)(tcm)(2)](n) (1), [Cu(bpy)(tcm)(2)](n) (2), [Cu(4)(bpz)(4)(tcm)(8)] (3), {[Cu(terpy)(tcm)].tcm}(n) (4) and {[Cu(2)(tppz)(tcm)(4)].3/2H(2)O}(n) (5) [pyim = 2-(2-pyridyl)imidazole, tcm = tricyanomethanide, bpy = 2,2'-bipyridine, bpz = 2,2'-bipyrazine, terpy = 2,2':6',2'-terpyridine and tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine] are reported. Complexes, 1, 2 and 4 are uniform copper(II) chains with single- (1 and 4) and double-(2) micro-1,5-tcm bridges with values of the intrachain copper-copper separation of 7.489(1) (1), 7.520(1) and 7.758(1) (2) and 7.469(1) A (4). Each copper atom in 1, 2 and 4 is five-coordinate with bidentate pyim (1)/bpy (2) and tridentate terpy (4) ligands and nitrile-nitrogen atoms from bridging (1,2 and 4) and terminal (1) tcm groups building a distorted square pyramidal surrounding. The structure of 3 is made up of neutral centrosymmetric rectangles of (2,2'-bipyrazine)copper(II) units at the corners, the edges being built by single- and double-micro-1,5-tcm bridges with copper-copper separations of 7.969(1) and 7.270(1) A, respectively. Five- and six-coordinated copper atoms with distorted square pyramidal and elongated octahedral environments occur in . Compound 5 is a neutral copper(II) chain with regular alternating bis-tridentate tppz and double micro-1,5-tcm bridges, the intrachain copper-copper distances being 6.549(7) and 7.668(1) A, respectively. The two crystallographically independent copper atoms in 5 have an elongated octahedral geometry with three tppz nitrogen atoms and a nitrile-nitrogen atom from a bridging tcm group in the equatorial positions, and two nitrile nitrogen atoms from a terminal and a bridging tcm ligand occupying the axial sites. The investigation of the magnetic properies of 1-5 in the temperature range 1.9-295 K has shown the occurrence of weak ferro- [J = +0.11(1) cm(-1) (2)] and antiferromagnetic interactions [J = -0.093(1) (1), -0.083(1) (4), -0.04(1) and 1.21(1) cm(-1) (3)] across the micro-1,5-tcm bridges and intermediate antiferromagnetic coupling [-J = 37.4(1) cm(-1) (5)] through bis-tridentate tppz. The values of the magnetic interactions are analyzed through simple orbital symmetry considerations and compared with those previously reported for related systems.     

Synthesis, characterization and biological activity of ternary copper(II) complexes containing polypyridyl ligands

Ternary copper(II) complexes involving polypyridyl ligands in the coordination sphere of composition [Cu(tpy)(phen)](ClO4)2 (1), [Cu(tpy)(bipy)](ClO4)2 (2), [Cu(tptz)(phen)](ClO4)2 (3) and [Cu(tptz)(bipy)](BF4)2 (4) where tpy = 2,2':6',2'-terpyridine, tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazine, phen = 1,10-phenanthroline and bipy = 2,2'-bipyridine have been synthesized and characterized by elemental analysis, magnetic susceptibility, X-band e.p.r. spectroscopy and electronic spectroscopy. Single crystal X-ray of (1) has revealed the presence of a distorted square pyramidal geometry in the complex. Magnetic susceptibility measurements at room temperature were in the range of 1.77-1.81 BM. SOD and antimicrobial activities of these complexes were also measured. Crystal data of (1): P-1, a = 9.3010(7) A, b = 9.7900(6) A, c = 16.4620(6) A, Vc = 1342.73(14) A3, Z = 4. The bond distance of CuN in square base is 2+/-0.04 A.     

Synthesis,crystal structures and properties of two copper(II) 2-aminomethylbenzimidazole complexes

Two new Cu^II complexes, [Cu(Hambi)₂(ClO₄)₂] and [Cu(Hambi)₂(dca)₂] (Hambi = 2-aminomethylbenzimidazole) have been prepared and characterized by X-ray diffraction, electronic paramagnetic resonance (e.p.r.) and i.r. analyses. Both complexes exhibit an elongated octahedral coordination environment with two Hambi ligands situated at the equatorial positions in a trans fashion [Cu—N bond distances range from 1.940(9) to 2.031(9) Å]. In the second complex, a new coordination mode, in which dicyanamide coordinates to copper(II) as a monodentate ligand with the amide nitrogen atom, was observed.     

Synthesis, characterization, and X-ray crystal structures of copper(II) and nickel(II) complexes with Schiff base

New copper(II) complexes, [Cu₂L¹L²] · ClO₄ (I) and [Ni(L³)₂] (II), where L¹ is the monoanionic form of 2-[1-(2-emthylaminoethylimino)ethyl]phenol, L² is the dianionic form of N,N′-ethylene-bis(2-hydroxyacetophenonylideneimine), L³ is the mono-anionic form of 2-(1-iminoethyl)phenol, were prepared and characterized using elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction. In complex I, the Cu(1) atom is coordinated by the NNO tridentate ligand L¹ and the two phenolate O atoms of L², forming a square pyramidal geometry. The Cu(2) atom in complex I is coordinated by the NNOO tetradenate ligand L², forming a square planar geometry. The Ni atom in complex II is coordinated by two phenolate O and two imine N atoms from two ligands L³, forming a square planar geometry. In the crystal structure of I, the perchlorate anions are linked to the dinuclear copper(II) complex cations through intermolecular N-H...O hydrogen bonds. In the crystal structure of II, the mononuclear nickel complex molecules are linked through intermolecular N-H...O hydrogen bonds, forming a trimer.     

Synthesis and crystal structures of two azido-bridged copper(II) complexes with schiff bases

Two new end-on azido-bridged dinuclear copper(II) complexes with the formula [Cu(μ_1,1-N₃)₂(IEP)₂] (I) and [Cu(μ_1,1-N₃)₂(EMP)₂] (II), where IEP and EMP are the deprotonated forms of 2-[1-(2-isopropylaminoethylimino)ethyl]phenol and 2-ethoxy-6-[(2-methylaminoeth-ylimino)methyl]phenol, respectively, were synthesized. Both complexes were characterized by elemental analyses and IR spectra. The crystal structures were determined by the X-ray diffraction. The crystal of I is monoclinic: space group P2₁/c, a = 9.662(2), b = 15.282(3), c = 10.639(2) Å, β = 115.418(10)°, V = 1418.9(5) ų, Z = 2. The crystal of II is monoclinic: space group P2₁/n, a = 12.588(2), b = 7.705(1), c = 14.481(2), β = 91.736(5)°, V = 1403.9(2) ų, Z = 2. The two Cu atoms in each complex are bridged by two end-on azide groups. Each Cu atom is in a square pyramidal coordination. The Cu…Cu distances are 3.230(2) Å in I and 3.150(2) Å in II.     

Synthesis,characterization and crystal structure of ternary chloroacetate,dichloroacetate and trichloroacetate copper(II) complexes

Three binuclear ternary copper(II) chloroacetate complexes with OP(OMe)₃ were prepared, and the configurations of the copper(II) dichloroacetate and trichloroacetate complexes were converted from a square-planar structure into a binuclear cage structure during the reaction. The crystal structure of Cu₂(ClCH₂CO₂)₄[OP(OMe)₃]₂ were determined by single-crystal X-ray diffraction. The i.r. spectra show that the carboxylate groups behave as bridging bidentate ligands in Cu₂(ClCH₂CO₂)₄(H₂O)₂ (1), Cu₂(ClCH₂CO₂)₄[OP(OMe)₃]₂ (4), Cu₂(Cl₂CHCO₂)₄-[OP(OMe)₃]₂ (5) and Cu₂(Cl₃CCO₂)₄[OP(OMe)₃]₂ (6), and as monodentate ligands in Cu(Cl₂CHCO₂)₂(H₂O)₂ (2) and Cu(Cl₃CCO₂)₂(H₂O)₂ (3). The electronic reflectance spectra in the solid state suggest a square pyramidal coordination environment around the copper(II) atom in (1), (4), (5) and (6), and a square-planar coordination environment in (2) and (3). Room temperature X-band e.s.r. spectra of powdered samples studied indicate the presence of electron coupling of copper(II) ions in (1), (4), (5) and (6).     

Synthesis,characterization and function of ternary copper(II) complexes

Ternary complexes of glycine, alanine, -alanine, serine and ethylenediamine with copper iminodiacetate have been prepared and characterized by their i.r., u.v.-vis. and e.s.r. spectra. The data suggest that the complexes possess axial symmetry and a distorted octahedral configuration in aqueous solution. The H2O molecule on the axial copper site can be replaced by O2–. The bonding parameters, which fall between 0.84 and 0.88, indicate that the bonds between copper(II) and the ligands possess more ionic character. The ternary complex containing serine displays the highest catalytic activity in dismutation of the superoxide radical O2–. This activity may be explained on the basis of the stabilization of CuII-O2– by hydrogen bonding.     

Synthesis,crystal structures and characterizations of three new copper(II) complexes including anti‐inflammatory diclofenac

Three new diclofenac‐based copper(II) complexes, namely tetrakis{μ‐2‐[2‐(2,6‐dichloroanilino)phenyl]acetato‐κ²O:O′}bis(methanol‐κO)copper(II), [Cu₂(μ‐dicl)₄(CH₃OH)₂] ( 1 ), bis{2‐[2‐(2,6‐dichloroanilino)phenyl]acetato‐κ²O,O′}bis(1‐vinyl‐1H‐imidazole‐κN³)copper(II), [Cu(dicl)₂(vim)₂] ( 2 ), and bis{2‐[2‐(2,6‐dichloroanilino)phenyl]acetato‐κ²O,O′}bis(1H‐imidazole‐κN³)copper(II), [Cu(dicl)₂(im)₂] ( 3 ) [dicl is diclofenac (C₁₄H₁₀Cl₂NO₂), vim is 1‐vinylimidazole (C₅H₆N₂) and im is imidazole (C₃H₄N₂)], have been synthesized and characterized by elemental analysis, FT–IR spectroscopy, thermal analysis and single‐crystal X‐ray diffraction. X‐ray diffraction analysis shows that complex 1 consists of dimeric units in which the dicl ligand exhibits a bidentate syn,syn‐μ₂ coordination mode linking two copper(II) centres. Complexes 2 and 3 have mononuclear units with the general formula [Cu(dicl)₂L₂] (L is vim or im) in which the Cu^II ions are octahedrally coordinated by two L and two dicl chelating ligands. The L and dicl ligands both occupy the trans positions of the coordination octahedron. The different coordination modes of dicl in the title complexes were revealed by Fourier transform IR (FT–IR) spectroscopy. The spin matching between the copper(II) centres in the dimeric [Cu₂(μ‐dicl)₄(CH₃OH)₂] units was also confirmed by magnetic data to be lower than the spin‐only value and electron paramagnetic resonance (EPR) spectra. The thermal properties of the complexes were investigated by thermogravimetric (TG) and differential thermal analysis (DTA) techniques.     

Synthesis,crystal structures and physical properties of two terephthalate-bridged copper(II) and nickel(II) complexes

Two ₂-terephthalate (tp) bridged complexes, [Cu₂(tp)(pren)₄](ClO₄)₂ (pren = 1,3-diaminopropane) (1) and [Ni₂(tp)(pren)₄(Him)₂](ClO₄)₂ (Him = imidazole) (2), have been synthesized and characterized by X-ray single-crystal structural analysis. In the discrete dinuclear [Cu₂(tp)(pren)₄]²⁺ cation of complex (1), each Cu^II atom has a square-pyramidal geometry, being coordinated by four nitrogen atoms (avg. 2.031 Å) from two pren ligands at the basal plane and one oxygen atom [2.259(3) Å] from a bis-monodentate tp group at the axial position. In the discrete dinuclear [Ni₂(tp)(pren)₄(Him)₂]²⁺ cation of complex (2), each Ni^II center is coordinated by five nitrogen atoms [Ni—N 2.069(3)–2.109(2) Å] from one Him group and two pren groups, and completed by one oxygen atom [Ni—O 2.138(3) Å] from a bis-monodentate tp group to furnish a distorted octahedron. Magnetic susceptibility studies show that the pair of metal atoms, although being separated by >11.5 Å, exhibit weak intramolecular antiferromagnetic interactions in complexes (1) (g = 2.07 and J = –3.4 cm^–1) and (2) (g = 2.10 and J = –0.7 cm^–1). The electrochemical behaviors of the complexes have also been studied by cyclic voltammogram processes.     

Synthesis, crystal structures and DNA-binding properties of two new mononuclear copper(II) complexes

Two mononuclear copper(II) complexes, [Cu(bpy)₂(CH₃OH)](pic)₂ (1) and [Cu(Me₂bpy)₂(H₂O)](pic)₂ (2) (bpy = 2,2′-bipyridine; Me₂bpy = 4,4′-dimethyl-2,2′-bipyridine; Hpic = 2,4,6-trinitrophenol), were synthesized and characterized by elemental analyses, conductivity measurements, IR, UV–Visible spectroscopy and single crystal X-ray analyses. Both complexes 1 and 2 are mononuclear compounds. The copper atom in complex 1 is in a distorted square pyramidal geometry with a CuN₄O chromophore as revealed from the τ value (0.25), while the Cu(II) ion in complex 2 displays a distorted trigonal bipyramidal stereochemistry with τ = 0.72. Hydrogen bonding interactions and π–π stacking interactions link the mononuclear copper complex 1 or 2 into a 1D infinite chain. The interactions of the two mononuclear complexes with herring sperm DNA (HS-DNA) have been studied by UV–visible absorption titration, fluorescence titration and ethidium bromide (EB) displacement experiments. The results suggest that both complexes might bind to DNA by intercalation.     

Synthesis,crystal structures and magnetic properties of nitronyl nitroxide radical-coordinated copper(II) complexes

Transition Metal Chemistry - The coordination compound constructed for nitronyl nitroxide radical NIT-Ph-4-Br and CuII(hfac)2(H2O)2 building blocks...     

Complexes of pendant-armed cyclam derivatives with copper(II) perchlorate: Synthesis and crystal structures

A designed series of cyclam type macrocyclic ligands 1–3 that feature a different degree of saturation and number of functional appendages of the macroring, including preparation of the respective Cu(II) perchlorate complexes 1a–3a, was synthesized. Comparative discussion of the X-ray crystal structures of the free ligands and the corresponding complexes shows that dependent on the structure of the compound, transanular, pendant arm and anion involving conventional and weaker H bond contacts are operating. In the complexes, the coordination environment around the Cu(II) cation is distorted octahedral with the nitrogens of the macroring defining the equatorial sites and either two oxygens, each of a perchlorate anion, or the lateral pyridine nitrogens in apical positions. Thus, only the pyridine containing pendants in 3a proved effective in metal ion coordination while the anisyl groups are engaged in H bonding, respectively. The uncomplexed macrocycle 3 yielded an inclusion compound with chloroform, also indicating a special ability relating to this series of compounds.     

Synthesis,crystal structures and magnetic and electrochemiluminescence properties of three manganese(II) complexes

Three novel complexes, namely, penta‐μ‐acetato‐bis(μ₂‐2‐{[2‐(6‐chloropyridin‐2‐yl)hydrazinylidene]methyl}‐6‐methoxyphenolato)‐μ‐formato‐tetramanganese(II), [Mn₄(C₁₃H₁₁ClN₃O₂)₂(C₂H₃O₂)_5.168(CHO₂)_0.832], 1 , hexa‐μ₂‐acetato‐bis(μ₂‐2‐{[2‐(6‐bromopyridin‐2‐yl)hydrazinylidene]methyl}‐6‐methoxyphenolato)tetramanganese(II), [Mn₄(C₁₃H₁₁BrN₃O₂)₂(C₂H₃O₂)₆], 2 , and catena‐poly[[μ₂‐acetato‐acetatoaqua(μ₂‐2‐{[2‐(6‐chloropyridin‐2‐yl)hydrazinylidene]methyl}‐6‐methoxyphenolato)dimanganese(II)]‐μ₂‐acetato], [Mn₂(C₁₃H₁₁ClN₃O₂)(C₂H₃O₂)₃(H₂O)]_n, 3 , have been synthesized using solvothermal methods. Complexes 1 – 3 were characterized by IR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction. Complexes 1 and 2 are tetranuclear manganese clusters, while complex 3 has a one‐dimensional network based on tetranuclear Mn₄(L¹)₂(CH₃COO)₆(H₂O)₂ building units (L¹ is 2‐{[2‐(6‐chloropyridin‐2‐yl)hydrazinylidene]methyl}‐6‐methoxyphenolate). Magnetic studies reveal that complexes 1 – 3 display dominant antiferromagnetic interactions between Mn^II ions through μ₂‐O bridges. In addition, 1 – 3 also display favourable electrochemiluminescence (ECL) properties.     

Synthesis,characterization, and thermal decomposition of fluorinated salicylaldehyde Schiff base derivatives (salen) and their complexes with copper(II)

Trifluoromethoxy functionalized copper(II) Schiff base complexes N,N′-bis(5-trifluoromethoxysalicylaldehyde)cyclohexanediiminatodiaquacopper(II) and N,N′-bis(5-trifluoromethoxysalicylaldehyde)phenylenediiminatocopper(II) were synthesized and characterized. Thermal decompositions of the synthesized complexes were studied by thermogravimetry in order to evaluate their thermal stability and thermal decomposition pathways. Three similar decomposition steps occurred for the two copper complexes. Mass losses and evolved gasses were characterized by TG/DTA-MS. Kinetic parameters were calculated and the results showed that the values obtained are comparable.     

Syntheses,crystal structures and thermal behavior of three Mn(II) complexes with 4-acyl pyrazolone derivatives

Three new manganese complexes, [Mn(PPeAP-INH)(CH₃OH)₂]_n(CHCl₃) (1) [PPeAP-INH=N-(1-phenyl-3-phenylethyl-4-ethylene-5-pyrazolone isoniazid, INH = isoniazid], [Mn₂(PM4MbP-INH)₂(CH₃OH)₄](CH₃OH) (2·CH₃OH), [PM4MbP-INH=N-(1-phenyl-3-methyl-4-(p-methylbenzoylene)-5-pyrazolone) isoniazid)] and [Mn₂(PPePeP-INH)₂(CH₃OH)₄] (3) [PPePeP-INH=N-(1-phenyl-3-phenylethyl-4-phenylethylene-5-pyrazolone) isoniazid] have been prepared, aiming at the formation of extended coordination polymer with Mn(II) ions. Formation of the corresponding manganese-ligand complexes has been monitored and characterized by chemical and spectroscopic techniques. X-ray diffraction analyses of available single crystals revealed 1D polymeric patterns of supramolecular system. Among them, the dimers of 2 and 3, bridged by two methanol molecules, are extended by hydrogen bond of O–H···N to form the 1D chain. In these three new complexes which are all octahedral coordination environments, the N(5) atom of the pyridine heterocycles plays a very important role in building the bridged polymeric chain.     

Synthesis, crystal structures, and magnetic properties of tetranuclear nickel(II) and copper(II) complexes with tridentate Schiff bases

Two cubane-type tetranuclear nickel(II) and copper(II) complexes, [Ni₄(L¹)₄(CH₃OH)₄] (1) and [Cu₄(L²)₄]·H₂O (2), where L¹ and L² are the dianionic forms of the tridentate Schiff bases 4-nitro-2-[(2-hydroxyethylimino)methyl]phenol (H₂L¹) and 5-methoxy-2-[(2-hydroxyethylimino)methyl]phenol (H₂L²), respectively, have been synthesized and characterized by physicochemical methods and single-crystal X-ray diffraction. The magnetic properties of the complexes show the presence of ferromagnetic interactions for complex 1 and antiferromagnetic interactions for complex 2, mediated by hydroxyl bridges.     

Synthesis,crystal structures,and magnetic properties of three new iron(II) complexes with pyrrolyl-substituted triaryltriazoles

Three pyrrolyl-substituted triaryltriazoles, 3-(N-methyl-2-pyrrolyl)-4-(p-R-phenyl)-5-(2-pyridyl)-1,2,4-triazole (L¹: R = MeO; L²: R = Cl; L³: R = Br), and their mononuclear iron(II) complexes, trans-[Fe(L^1–3)₂(NCS)₂]?2MeOH (1: L¹; 2: L²; 3: L³), have been synthesized and characterized by elemental analysis, FT-IR, ESI-MS, and single-crystal X-ray crystallography. Crystallographic studies revealed that 1–3 are isomorphous and crystallize in the triclinic space group P-1. All the complexes have a similar octahedral [FeN₆] core with two trans-NCS^? ions. Each ligand adopts a chelating bidentate coordination mode via the pyridyl N and one N of the triazole. Intermolecular O–H?O hydrogen bonding and C–H?π interactions link the molecules of 1–3 to form a 1-D chain or 2-D framework. Variable-temperature magnetic susceptibility measurements indicated that all the complexes remained in a high-spin state from 1.8 to 300 K and had a weak antiferromagnetic interaction.     

Synthesis and X-ray crystal structures of three copper(II) complexes of 1,4- bis (di-2-pyridylmethyl)phthalazine

The synthesis and X-ray crystal structures of three discrete copper(II) complexes of 1,4-bis(di-2-pyridylmethyl)phthalazine (L) are reported. The complexes 1–3 have Cu₂L, Cu₃L and Cu₂L₂ composition and display interesting relationships to previously reported complexes of this ligand.     

Heteroligand zinc(II) and copper(II) complexes with naphthylacetic acid and monoethanolamine: Syntheses and crystal structures

New heteroligand Cu(II) and Zn(II) complexes with the α-naphthylacetic acid anion (NAA) and monoethanolamine (MEA), [M(NAA)₂(MEA)₂] (M = Cu²⁺, (I), Zn²⁺ (II)), are synthesized. The crystal structures of the obtained complexes are determined by X-ray diffraction analysis (CIF files CCDC 984097 (I) and 930946 (II)). The crystals are monoclinic, for I: a = 18.8140(9) Å, b = 4.82500(14) Å, c = 16.0360(7) Å, β = 115.135(6)°, V = 1317.87(11) ų, space group P2₁/c, Z = 2; for II: a = 32.9760(14) Å, b = 5.0911(3) Å, c = 15.7994(10) Å, β = 94.418(5)°, V = 2644.6(3) ų, space group C2/c, Z = 4. In the structure of complex I, the Cu²⁺ ion arranged in the symmetry center is coordinated at the vertices of the distorted octahedron by the oxygen atoms of two NAA molecules (Cu-O(2) 2.019(4) Å) and two MEA molecules. The latter is the bidentate-chelating ligand and coordinates the metal through the O and N atoms to form the five-membered metallocycle (Cu-O(3) 2.457(5), Cu-N(1) 1.986(5) Å). In complex II, the Zn atom (on axis 2) is coordinated at the vertices of the distorted tetrahedron by the oxygen atoms of two NAA molecules (Zn-O(2) 1.976(4) Å) and the nitrogen atoms of two MEA molecules (Zn-N 2.034(6) Å). The character of the interaction of coordinated NAA and MEA ligands and methods for packing complexes I and II are considered on the basis of the structural data.