Synthesis and characterization of two acetato-bridged dinuclear copper(II) complexes with 4-bromo-2-((4 or 6-methylpyridin-2-ylimino)methyl)phenol as ligand (original) (raw)
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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.
Inorganic Chemistry, 2004
Copper(II) complexes (1−3) of a sterically constrained phenol-based tetradentate N 2 O 2 ligand 1,4-bis(2-hydroxy-3,5-dimethylbenzyl)piperazine (H 2 L) have been reported. The associated anions of the copper(II) ion precursors have profound influence on the stoichiometry of the products. Thus, with perchlorate ion, the product is a binuclear compound [Cu 2 L 2 ] (1), while with coordinating anions viz. Cland N 3-, the products [Cu 3 L 2 Cl 2 (H 2 O)]‚1/2H 2 L (2) and [Cu 3 L 2 (N 3) 2 (CH 3 OH)]‚4H 2 O (3) have triangulo trinuclear composition. The syntheses, X-ray structures, and spectroscopic and magnetic properties of these complexes are described. Compound 1 has a noncentrosymmetric structure with a rectangular Cu 2 (OPh) 2 core. It appears to be a rare example of a phenolato-bridged Cu(II) dimer exhibiting ferromagnetic interactions (J) 0.93 cm-1), a behavior in agreement with the theoretical predictions but seldom observed experimentally. In compounds 2 and 3, the copper centers are triangularly disposed, and the molecules have a shape much like that of a butterfly. The terminal copper centers Cu(1) and Cu(2) in 2 and 3 have distorted square pyramidal geometry, connected to each other by a bridging chloro-(in 2) or azido ligand (in 3) in "end to end" fashion. The central copper center (Cu(3) in 2 and Cu in 3) in both the compounds has distorted square planar geometry. The separations between the metal centers, viz. Cu(1)‚‚‚Cu(2), Cu(2)‚‚‚Cu(3), and Cu-(3)‚‚‚Cu(1), are 4.826, 3.214, and 3.244 Å, respectively, in 2. The corresponding distances in 3 are 5.590, 3.178, and 3.485 Å, respectively. The overall magnetic behaviors in 2 and 3 are consistent with antiferromagnetic interactions between the spin centers. In 3, the exchange couplings between the terminal and central copper centers J Cu(1)-Cu and J Cu(2)-Cu appear to be equal (−234 cm-1), resulting in an S) 1 / 2 ground state at temperatures near or below 77 K.
Inorganica Chimica Acta, 1995
The crystal structures, spectroscopic and magnetic properties of two dinuclear copper(II) coordination compounds containing the ligand N3-salicyloylpyridine-2-carboxamidrazonato (abbreviated as spa) are reported. Compound 1, bis[(N3-salicyloylpyridine-2-carboxamidrazonato-N 1, N2,O)aquacopper(II)nitrate], [Cu(spa)(H20)(NO3)]:, Cu2C26H~N10On, crystallizes in the triclinic space group P1, with a = 8.898(1), b = 12.472(4), c = 14.063(5) /~, a = 91.15(3), /3 = 97.48(2), y= 102.25(2) °, V= 1511.8 /~3 and Z = 2 (dinuclear units). The least-squares refinement based on 3147 reflections, with I> 20(0, converged to R = 0.0501 and Rw = 0.0581. Two crystallographic independent five-coordinated copper(II) atoms are present in this structure, which differ slightly in bond distances and angles. Both metal ions are in a square pyramidal environment of which the basal plane is formed by two nitrogen and an oxygen donor atom of the spa ligand and a water molecule. A nitrate anion occupies the apical position. The mononuclear fragments of symmetry related metal ions are linked in dinuclear units via a four-fold hydrogen bonding network, with Cul-Cul' (l-x,1-y, 1-z)=4.723(2) /~ and Cu2-Cu2" (-x,-y,-z)=4.616(2) /~. Compound 2, bis[(N 3salicyloylpyridine-2-carboxamidrazonato-N ~, N2,O)diaquacopper(II)] diperchlorate, [Cu(spa)(H20)2]2(C104)2, Cu2C-~HaoNsO16CI2, crystallizes in the triclinic space group Pi, with a = 7.138(1), b = 10.655(2), c = 12.844(1) A,, a= 103.71(1),/3 = 98.43(1), y = 102.19(2) °, V=907.4 A. 3 and Z= 1 (dinuclear unit). The least-squares refinement based on 3022 reflections, with 1> 20(0, converged to R =0.0359 and Rw=0.0475. The copper(II) ion is in a distorted octahedron, with two N and an O donor atom of the spa ligand and a water molecule in the equatorial plane. An additional water molecule and a phenol-O are in the axial positions. There is an intramolecular stacking of two [Cu(spa)(H20)2] units, with Cu-Cu' (l-x;-y,-z)=6.2810(7) A. The X-band powder EPR spectra for [Cu(spa)(H20)(NO3)]2 show the usual spectrum for copper(II) ions in an axial symmetry. For [Cu(spa)(H20)2]2(CIO4)2 the signals at g=4.04, 3.02, 2.08 and 1.66, give evidence for Cu...Cu exchange splittings, although the magnetic interaction is extremely weak and could not be detected by magnetic susceptibility measurements over the temperature range 10-280 K.
Polyhedron, 2010
Five new complexes of copper(II) having the general formula [CuL(OAc)], where HL and OAc À represent the N,N,O-donor 4-R-2-[(2-pyridin-2-yl-ethylimino)-methyl]-phenol (R = H, Br, NO 2 and OMe) or 5methoxy-2-[(2-pyridin-2-yl-ethylimino)-methyl]-phenol and acetate, respectively have been reported. The complexes have been synthesized in 52-80% yields by reacting one mole equivalent each of Cu(OAc) 2 ÁH 2 O, 2-(2-aminoethyl)pyridine and the appropriate substituted salicylaldehyde in methanol. The solid state effective magnetic moments of the complexes at 298 K are within 1.79-1.97 l B. In solution, all the complexes are electrically non-conducting. The electronic spectra of these species display a weak ligand-field band within 640-615 nm and several strong charge transfer bands in the range 410-235 nm. The complexes are EPR active. The frozen (120 K) solution spectral parameters are g || = 2.22-2.23, A || = 189-191 Â 10 À4 cm À1 , g ? = 2.06-2.07, and A ?ðNÞ = 10-16 Â 10 À4 cm À1. X-ray structures show that the ligand L À coordinates the metal center through the phenolate-O, the imine-N and the pyridine-N and forms two six-membered chelate rings. The acetate is bidentate but asymmetric with respect to the Cu-O as well as CO bond lengths. Only the complex where R = Br dimerises due to two reciprocal CuÁ Á ÁBr interactions.
Polyhedron, 2009
The copper(II) complexes of formula [Cu 2 (2,5-dpp)(H 2 O) 4 (CF 3 SO 3) 4 ] Á 2H 2 O (1) and [Cu 2 (2,5dpp)(H 2 O) 2 (tcnoet) 4 ] n (2) [2,5-dpp = 2,5-bis(2-pyridyl)pyrazine and tcnoet À = 1,1,3,3-tetracyano-2-ethoxypropenide anion] have been prepared and their structures determined by X-ray crystallographic methods. Compound 1 is a dinuclear complex where the 2,5-dpp molecule acts as a bis-bidentate bridge between the two copper centers, the electroneutrality being achieved by four terminally bound triflate anions. Each copper(II) ion presents an elongated octahedral CuN 2 O 4 environment with two nitrogen atoms from 2,5-dpp and two water molecules in the basal plane and two triflate-oxygen atoms in the axial positions. Compound 2 is a zigzag chain of copper(II) ions with regular alternating 2,5-dpp and double tcnoet groups as bridges. Each copper(II) ion exhibits an elongated octahedral CuN 5 O surrounding with four nitrogen atoms, two from 2,5-dpp, one from a terminally bound tcnoet and the other from a bridging tcnoet occupying the equatorial positions and a water oxygen and a nitrogen from a monodentate tcnoet in the axial sites. The values of the copper-copper separation across 2,5-dpp are 6.763(1) (1) and 6.754(1) Å (2) whereas that through the double tcnoet bridge is 9.559(1) Å (2). The investigation of the magnetic properties of 1 and 2 in the temperature range 1.9-295 K reveal a Curie law behaviour for 1 and a very weak ferromagnetic interaction for 2. The poor ability of the 2,5-dpp ligand to mediate magnetic interactions between the copper(II) ions in the 2,5-dpp-bridged copper(II) complexes contrast with the somewhat better ability of the pyrazine ring in related pyrazine-bridged copper(II) complexes.
Inorganica Chimica Acta, 2012
The formation and the magnetic properties of the copper(II) compounds [Cu(L1)(py)](ClO4) (1a) and [Cu(L2)(py)](ClO4) (2a), bearing the NNO tridentate Schiff base ligand L1- = (E)-2-((3-aminoethylimino)methyl)phenolate or L2- = (E)-2-((3-aminopropylimino)methyl)phenolate (obtained by monocondensation of salicylaldehyde, salH, and ethylenediamine, en, or 1,3-propylenediamine, tn, respectively) and pyridine (py) are presented. These complexes are converted into new mono-, di- and trinuclear derivatives, whose nature depends on the length of the diamine used and hence on the size of the corresponding metallacycle. Pyridine can be substituted by a molecule of N,N-dimethylformamide (DMF) in compound 2a, leading to the mononuclear [Cu(L2)(dmf)](ClO4) (2b), while 1a undergoes only decomposition under similar conditions. Pyrazine does not act as bridging ligand between two copper centres by substitution of py, but its reaction with 2a yields either the dinuclear compound [Cu2(L2)2(ClO4)2] (2c), with exclusion of pyridine, or the trinuclear [Cu3(L2)3(l3-OH)](ClO4)2 (2d), where pyrazine acts as base generating OH-, and it does not appear in the product. Reaction of 1a with pyrazine yields only the trinuclear [Cu3(L1)3(mu3-OH)](ClO4)2 (1d). Also with 2,2'-bipyridine (2,2'-bpy) dinuclear complexes are not formed, but bpy acts as bidentate ligand to copper yielding the pentacoordinated mononuclear compounds [Cu(L1)(2,2'-bpy)](ClO4) (1e) and [Cu(L2)(2,2'-bpy)](ClO4) (2e). The crystal structures of compounds 2b, 2c and 1e have been solved and are reported. The magnetic susceptibilities vM(T) of 1a and 2a have been studied, showing the absence of any measurable Cu–Cu interaction for 1a (en, fivemembered ring), while a weak but interesting intermolecular Cu–Cu ferromagnetic coupling (J = +0.96(3) cm-1) through the short dimeric Cu...O contacts is detected for 2a (tn, six-membered ring). The X-band EPR spectrum of 2a in a frozen methanol solution at 70 K shows the hyperfine coupling of mononuclear copper with the three coordinated 14N atoms, yielding seven narrow lines.
Australian Journal of Chemistry, 2012
Two novel trinuclear CuII complexes have been synthesised from the nucleophilic addition derivatives of the small cyano anion, dicyanonitrosomethanide (dcnm). The reaction of CuII with the water adduct ligand, carbamoylcyanonitrosomethanide (ccnm) and teaH3 (triethanolamine) in a basic MeOH/MeCN solution results in the formation of [Cu3(acnm)2(teaH2)2]·2MeOH (1) (acnm = amidocarbonyl(cyano)nitrosomethanide and teaH2– = singly deprotonated triethanolamine). The reaction of CuII with dicyanonitrosomethanide (dcnm) and m-xylenediamine in a basic MeOH/MeCN solution results in the formation of [Cu3(cimm)2(a3acnm)2]·6MeCN (2) (cimm = cyano(imido(methoxy)methyl)nitrosomethanide and a3acnm = {amino(3-aminomethylphenyl)methylimino}methyl(cyanonitrosomethanide)). Both complexes display linear trinuclear CuII metallic cores. Solid state DC magnetic susceptibility studies were performed on 1 and 2. Compound 1 revealed very strong antiferromagnetic interactions between central and terminal Cu at...
Strong antiferromagnetic coupling in doubly N, O oximato-bridged dinuclear copper(II) complexes
Polyhedron, 2010
The use of di-2-pyridyl ketone oxime, (py)pkoH, and phenyl 2-pyridyl ketone oxime, ppkoH, in copper(II) hexafluoroacetylacetonate chemistry is reported. The reaction of CuCl 2 Á2H 2 O with one and two equivalents of ppkoH and Na(hfac), respectively, in CH 2 Cl 2 affords the dinuclear complex [Cu 2 (hfac) 2 (ppko) 2 ] (1) in excellent yield. The replacement of ppkoH by (py)pkoH gives the isostructural compound [Cu 2 (hfac) 2 {(py)pko} 2 ] (2) in good yield. The Cu II atoms in both 1 and 2 are doubly bridged by the oximate groups of two g 1 :g 1 :g 1 :l 2 ppko À and (py)pko À ligands, respectively. The bridging Cu-(R-NO)-Cu 0 units are not planar, with the torsion angles being 23.2°(1) and 20.3°(2). A bidentate chelating hfac À ligand completes five-coordination at each square pyramidal metal ion. The hfac À -free reaction system CuCl 2 Á2H 2 O/(py)pkoH/NEt 3 (1:2:1) gives instead the mononuclear complex [CuCl{(py)pko}{(py)pkoH}] (3) in very good yield. The Cu II atom is coordinated by two N,N 0 -bidentate (py)pko À /(py)pkoH chelates and a monodentate chloride anion resulting in a distorted square pyramidal geometry around the metal center. Variable-temperature, solid-state dc magnetic studies were carried out on the representative dinuclear complex 1 in the 2.0-300 K range. The data indicate a very strong antiferromagnetic exchange interaction and a resulting S = 0 ground state, which is well isolated from the S = 1 excited state. The J value of À720 cm À1 was derived from the fitting of the experimental data using the Hamiltonian H = ÀJ(S 1 Á S 2 ).