Study of copper(II) thiophenecarboxylate complexes with N-methylnicotinamide (original) (raw)
Related papers
Study of copper(II) thiophenecarboxylate complexes with nicotinamide
Polyhedron, 2012
The synthesis and characterization of [Cu(3-Me-2-tpc) 2 (nia) 2 ] (1), [Cu(5-Me-2-tpc) 2 (nia) 2 ] (2), [Cu(2tpc) 2 (nia) 2 ] (3) and [Cu(5-Me-2-tpc) 2 (nia) 2 (H 2 O)] (4) (where 2-tpc is 2-thiophenecarboxylate, 3-Me-2tpc is 3-methyl-2-thiophenecarboxylate, 5-Me-2-tpc is 5-methyl-2-thiophenecarboxylate and nia is nicotinamide) are reported. The complexes under study were characterized by electronic, IR, EPR spectroscopy, magnetic susceptibility over the temperature range and X-ray structure analysis. The coordination arrangement around each copper(II) atom is a distorted tetragonal bipyramidal. The discrepancies between two Cu-O axial bond distances increases in the order: 0 Å (complex 1) < 0.050 Å (complex 3) < 0.209 Å (complex 2) < 0.516 Å (complex 4, Cu1) < 0.746 Å (complex 4, Cu2), indicating that in the same order a distortion of the respective tetragonal bipyramids increases. This is in a good agreement with the ligand field band position in their electronic spectra. The complex molecules of all compounds are connected through H-bonds into supramolecular chains or frameworks. Spectral and magnetic behaviours are discussed with regard to X-ray parameters. Small negative value of Weiss constants confirm an existence of a very weak antiferromagnetic interaction between Cu(II) magnetic center in the crystal lattice. The EPR parameters are typical for a tetragonal bipyramidal Cu(II) complexes. The g av values at r.t. are somewhat lower than those at 77 K.
Crystal structures, spectra and magnetic properties of di-2-pyridylamine (dpa) CuII complexes [Cu(dpa)2(N3)2]·(H2O)2 and Cu2(μ-ox)(dpa)2(CH3CN)22
Inorganica Chimica Acta, 2003
Two Cu II complexes with di-2-pyridylamine (dpa) and combined bridging ligands (azide or oxalato anions), [Cu(dpa) 2 (N 3 ) 2 ] ×/ 2H 2 O (1) and [Cu 2 (m-ox)(dpa) 2 (CH 3 CN) 2 ](ClO 4 ) 2 (2), have been synthesized and characterized by IR spectra, elemental analyses, TGA, UV Á/Vis spectra and ESR technique. The crystal structures of both complexes have been determined by single crystal X-ray diffraction analyses. In the mononuclear complex 1, the Cu II center is coordinated to four N atoms of dpa and two N donors of azide (CuN 6 ), taking an elongated octahedral geometry. The solvent water molecules interlink the neutral [Cu(dpa) 2 (N 3 ) 2 ] units through hydrogen bonds to form a two-dimensional (2D) layered structure with strong p Á/p stacking interactions between the adjacent pyridine rings. Complex 2 is made up of centro-symmetric dinuclear [Cu 2 (m-ox)(dpa) 2 (CH 3 CN) 2 ] 2' cation and noncoordinated perchlorate anions, assembling into a one-dimensional (1D) ladder structure through hydrogen bonding with p Á/p stacking co-effect. The magnetic properties of 2 have been investigated by variable-temperature magnetic susceptibility and magnetization measurements, indicating a very strong anti-ferromagnetic coupling between the intra-molecular Cu II centers (having the perfect square-pyramidal geometry) with J 0/(/382 cm (1 . The strength of the exchange interaction is discussed in detail on the basis of the structural feature. #
Chemical Papers, 2017
The synthesis and characterization of [Cu(5-Me-2-tpc) 2 (4-pyme) 2 ] (I), [Cu(3-Me-2-tpc) 2 (4-pyme) 2 ] (II), [Cu(2-tpc) 2 (4-pyme) 2 ] (III), [Cu(2-tpc) 2 (isonia) 2 (2-tpcH)] (IV), [Cu(5-Me-2-tpc) 2 (isonia) 2 (5-Me-2-tpcH)] (V), [Cu 2 (2-tpc) 4 (4-pyme) 2 ] (VI), [Cu 2 (3-Me-2-tpc) 4 (isonia) 2 ] (VII) (where 2-tpc is 2-thiophenecarboxylate, 3-Me-2-tpc is 3-methyl-2-thiophenecarboxylate, 5-Me-2-tpc is 5-methyl-2-thiophenecarboxylate and 4-pyme is 4-pyridinemethanol and isonia is isonicotinamide) are reported. The complexes under study were characterized by electronic, IR and EPR spectroscopy, magnetic susceptibility over the temperature range and X-ray structure analysis. Structural studies revealed a distorted tetragonal-bipyramidal environment around the copper ion for monomeric complexes I-V. The structure of dimeric complexes VI and VII consists of units of the known paddle-wheel dicopper(II) tetracarboxylates, which are made up of four thiophene-2-carboxylate ions thus bridging the two copper atoms. The complex molecules of all compounds are connected through H-bonds into supramolecular chains or frameworks. The spectral and magnetic properties are discussed with regard to X-ray data.
Inorganica Chimica Acta, 2007
A new complex of composition [Cu(2-NO 2 bz) 2 (nia) 2 (H 2 O) 2 ] (1) (nia = nicotinamide, 2-NO 2 bz = 2-nitrobenzoate) has been prepared and its composition and stereochemistry as well as coordination mode have been determined by elemental analysis, electronic, infrared and EPR spectroscopy, magnetization measurements over the temperature range 1.8-300 K, and its structure has been solved, as well. The complex structure consists of the centrosymmetric molecules with Cu(II) atom monodentately coordinated by the pair of 2-nitrobenzoato anions and by the pair of nicotinamide molecules, forming nearly tetragonal basal plane, and by a pair of water molecules that complete tetragonal-bipyramidal coordination polyhedron about the copper atom. The complex 1 exhibits magnetic moment l eff = 1.86 B.M. at 300 K which decreases to l eff = 1.83 B.M. at 1.8 K. The magnetic susceptibility temperature dependence obeys Curie-Weiss law with Curie constant of 0.442 cm 3 K mol À1 and with Weiss constant of À1.0 K. EPR spectra at room temperature as well as at 77 K are of axial type with g^= 2.065 and g i = 2.280 and exhibit clearly, but partially resolved parallel hyperfine splitting with A II = 160 G, that is consistent with the determined molecular structure of 1. In order to analyze the factors influencing the degree of tetragonal distortion of coordination polyhedron, the dataset of 72 structures similar to that of 1 was extracted from CCD and analyzed. A significant correlation between the average Cu-O ax bond length and tetragonality parameter s which was found as a consequence of the Jahn-Teller effect.
Synthesis, structure, UV–Vis–IR spectra, magnetism and theoretical studies on CuII(2-aminomethyl)pyridine2 and comparisons with an analogous CuII complex
Polyhedron, 2011
The title complex was synthesized under self-assembly conditions using Cu(acetate) 2 ÁH 2 O, 2-amp (= 2-aminomethylpyridine) and KSCN, and was characterized by IR, elemental analysis and single crystal structural analysis, and its spectral and RT magnetic properties were investigated. The asymmetric unit consists of a square planar Cu(II) center, with two ligand N atoms and two anionic Ns forming the square plane. In the unit cell, the monomeric complex assembles into 2-D layers through very weak non-bonded interactions between anionic S and Cu 2+. Further, the structure was satisfactorily modeled by calculations based on Density Functional Theory (DFT), and the UV-Vis and IR spectra are analyzed in depth with the help of Time Dependent DFT (TDDFT). The results indicate that the absorption maxima are at relatively high energy and are mainly assigned to p ? p ⁄ transitions (in pyridine), with a fair contribution of metal to ligand charge transfer (MLCT) and ligand to ligand charge transfer (LLCT) transitions. All the low lying transitions are categorized as mixed MLCT/LLCT. A very weak but broad band in the higher wavelength region has been detected and identified as a d-d transition band. Also, it has been found that when the ligand ratio is modified, the formation of Cu(2-amp) 2 (SCN) 2 takes place under the same self-assembly conditions, whose structure only has been recently reported. Structural, spectral and theoretical comparisons are presented for both complexes.
ChemistrySelect, 2018
Two novel copper(II) complexes, [Cu 4 (L) 2 (LH) 2 (H 2 O) 2 ] 2 (NO 3) 2. (pydc).9H 2 O (1) and {[Cu 4 (L) 2 (LH) 2 (H 2 O) 2 (ppda)].5H 2 O} n (2) [H 2 L = 2-[(2-hydroxy-ethylimino)-methyl]-6-methoxy-phenol, pydc = pyridine-3,5-dicarboxylate, ppda = phenylene-1,4-diacrylate] have been synthesized and characterised by X-ray single crystal diffraction analysis and low temperature magnetic study. The structural determination reveals for complex 1 a tetranuclear species exhibiting a double-open cubane like core framework, whereas use of ppda anions results 1D coordination polymer where tetranuclear double-open cubane cores are connected by bridging ppda ligands. In both the complexes, hydrogen bonding interactions lead to 3D supramolecular structures. Low temperature magnetic study indicates antiferromagnetic coupling in both the complexes. A model based on an effective square tetramer of Heisenberg spins was used to determine exchange strengths of 174(2) K for 1 and 107.4(4) K for 2. Copper(II) complexes, especially those comprising a cubane-like Cu 4 O 4 core, have been widely studied with the aim to synthesize magnetic materials, [10] a route favoured by possible different coordination geometries of the metal and the presence of unpaired electrons. Mergehenn and Haase have proposed a classification of cubane-like complexes considering the distribution of Cu À O distance values within the cube. [11-13] Thus, compounds having four long Cu À O distances between two pseudodimeric units have been classified of type I (displaying dominant antiferromagnetic interactions), while compounds with a pair of long distances within each of the pseudodimeric units have been classified of type II (displaying dominant ferromagnetic interactions). On the other hand, based on Cu⋅⋅⋅Cu distances Ruiz et al. [14] classified cubane compounds as: (i)[2 + 4], complexes with two short and four long Cu⋅⋅⋅Cu distances; (ii) [4 + 2], complexes with four short and two long Cu⋅⋅⋅Cu distances; (iii) [6 + 0], complexes with six equivalent Cu⋅⋅⋅Cu distances. In the present contribution we have used a multidentate Schiff base ligand, 2-[(2-hydroxy-ethylimino)-methyl]-6-methoxy-phenol (H 2 L) in combination of aromatic dicarboxylate species to synthesize copper complexes of double open cubane like core structure, [Cu 4 (L) 2 (LH) 2 (H 2 O) 2 ] 2 (NO 3) 2. (pydc).9H 2 O (1) and {[Cu 4 (L) 2 (LH) 2 (H 2 O) 2 (ppda)].5H 2 O} n (2) (H 2 L = 2-[(2-hydroxy-ethylimino)-methyl]-6-methoxy-phenol, pydc = pyridine-3,5-dicarboxylate, ppda = phenylene-1,4-diacrylate). Variable temperature magnetic properties of the complexes have been studied.
Inorganic Chemistry, 2001
New Cu(II) complexes of sulfamethazine (4-amino-N-[4,6-dimethyl-2-pyrimidinyl]benzenesulfonamide, HL) [Cu 2 (CH 3 COO) 2 (L) 2 ]·2dmf (1) and {[Cu(L) 2 ]‚2H 2 O} ∞ (2) were prepared and structurally characterized. Compound 1 crystallizes in the monoclinic system, space group P2 1 /n, with a ) 8.9486(9) Å, b ) 15.0956(12) Å, c ) 16.542(3) Å, ) 105.584(15)°, and Z ) 2. Compound 2 crystallizes in the monoclinic system, space group P2 1 /c, with a ) 13.8097(8) Å, b ) 14.5765(4) Å, c ) 13.7853(15) Å, ) 96.033(9)°, and Z ) 1. In compound 1 two copper ions are linked by two syn-syn acetates and two nonlinear NCN bridging groups pertaining to the deprotonated sulfamethazine ligands. Each copper center presents a nearly square planar geometry. Magnetic susceptibility data for 1 show a strong antiferromagnetic coupling with 2J ) -216.7 cm -1 . The EPR spectra at the X-and Q-band frequencies present the signals corresponding to the dinuclear entity, being the zero-field splitting parameter, D ) 0.265 cm -1 . The antiferromagnetic exchange coupling is discussed using DFT calculations on some model compounds with NCN bridging ligands and also on model structures with mixed µ-acetato and NCN bridges. The copper in the polymeric compound 2 is five coordinate. The CuN 5 chromophore has a highly distorted square pyramidal geometry with small axial N-Cu-N angles of 65.53(14) and 59.90(13)°. In the structure a sulfamethazinate anion binds to one copper through the sulfonamido and pyrimidine N atoms and to an adjacent copper via the amino N atom.
Inorganica Chimica Acta, 2020
The chemical preparation, crystal structure and spectroscopic characterization of two new Cu(II) complexes [Cu(ampymo)4](O2CMe)2, ( 1 ) and [Cu(C5H7N3O)2(H2O)3](CH3COO)2, [Cu(ampymo)2(H2O)3](O2CMe)2, ( 2 ) with the monodentate ligand 2-amino-6-methylpyrimidin-4-(1H)-one, (ampymo), are reported. In ( 1 ), the Cu(II) atom is four-coordinated, in a square planar fashion, by nitrogen atoms of four ampymo ligands. In ( 2 ), it is five-coordinated in a square pyramidal fashion by two pyrimidine nitrogen atoms and three water oxygen atoms. The crystal structure of ( 1 ) is stabilized by N H⋯O hydrogen bonds with pillars of the cationic complexes alternating with channels occupied by the acetate anions. In the atomic arrangement of ( 2 ), the complex cations are located parallel to the (a, b) plane between which the acetate anions intercalate by establishing hydrogen bonds with these cations to form a tridimensional network. The vibrational absorption bands were identified by infrared spect...
Polyhedron, 2013
The 1D coordination polymers [Cu 2 (syn,syn-g 1 :g 1 :l-RCOO) 4 (anti,anti-g 1 :g 1 :l-RCOO)(Et 3 NH)] n , R = Me (1) and H (2), and the dimer [Cu 2 (syn,syn-g 1 :g 1 :l-PhCOO) 4 (anti-g 1 -PhCOO) 2 (Et 3 NH) 2 ] (3) are formed by reaction of copper carboxylates with the corresponding carboxylic acid and NEt 3 . Moreover, the compound [Cu 2 (syn,syn-g 1 :g 1 :l-MeCOO) 4 (anti-g 1 -MeCOO) 2 (Et 2 NH 2 ) 2 ] (4) can be obtained with the use of NHEt 2 . The crystal structures of 1ÁCH 3 CN and 2 comprise linear anionic 1D chains of paddle-wheel copper carboxylates [Cu 2 (RCOO) 4 ], bridged together by anti,anti-g 1 :g 1 :l acetato or formato ions. The negative charges are balanced by hydrogen-bonded triethylammonium countercations, and in compound 1 acetonitrile molecules are hosted in the voids between the chains. In compounds 3 and 4, two anti-g 1 -benzoato or -acetato anions occupy the apical positions of the paddle-wheel dimers [Cu 2 (RCOO) 4 ], with Et 3 NH + or Et 2 NH 2 + cations balancing the negative charges, without the formation of coordination polymer chains.