ne

ale

bDepartamento de Qumica, Centro de Investigacin y de Estudios Avanzados, Instituto Politcnico Nacional, Av. Instituto Politcnico Nacional 2508, San Pedro Zacatenco, DF,Mxico 07360, Mexicoc Facultad de Ciencias Qumicas, UANL, Guerrero y Progrd to Polit

103F, Co

ng 1D zcture co3)] linkare conll the m

a b s t r a c t

nologies [14]. By reducing Schiff bases, a newclass of amine ligandscan be obtained. As compared to the corresponding Schiff bases, thisclass of ligands has better conformational exibility and better abil-ity to form hydrogen bonds involving the amino groups [5]. On theother hand, studies of the properties of the Cu(II)-phenolato com-pounds are important because of their involvement in a range of bio-logical and catalytic processes [6,7]. An interesting synthetic

synthesis, the structural, electronic and magnetic studies of the[Cu(II)(saleanN3H3)] 1 complex are presented.

2. Experimental

2.1. Materials and instrumentation

The N,N00-bis(2-hydroxybenzyl)-diethylenetriamine (saleanN3H5)ligand is prepared as previously reported [12,13]. All reagents forsynthesis and analyses were of analytical grade.

Corresponding author. Fax: +52 22 295551.

Journal of Molecular Structure 1034 (2013) 183188

Contents lists available at

ec

lseE-mail address: yasmi.reyes@correo.buap.mx (Y. Reyes-Ortega).Article history:Available online 12 September 2012

Keywords:Cu(II) complexMagnetic studies1D-chainCrystal structureUVVisIR studies

[Cu(II)(saleanN3H3)] 1 (saleanN3H3 = N,N0 0-bis(2-oxybenzyl)-diethylenetriamine dianion) is obtained bydirect synthesis. 1 crystallizes in orthorhombic space group Pbca. The crystalline network featuresone-dimensional (1D) columns of zigzag chains well separated in the [100] direction. Each column isa supramolecular structure, with triangles formed among the Cu(II) ions of the chain. Local Cu(II) geom-etry in 1 is intermediate between square-pyramidal and trigonalbipyramidal conformations. UVVisspectrum, IR, and NMR 1H spectra prove the formation of 1. X-band ESR spectra at 77 K/300 K of a poly-crystalline sample show a broad singlet with temperature independent values g||/g\ = 2.1967/2.1074. Anarea ratio A77/A300 of 1.63 suggests an incomplete antiferromagnetic (AF) coupling of the copper ions. TheX-band ESR spectra at 77 K in solution show typical hyperne interactions of monomer paramagneticcopper ions. The linear chain model ts well the magnetic susceptibility data vs temperature from 2 to300 K and is consistent with antiferromagnetic exchange interaction.

2012 Elsevier B.V. All rights reserved.

1. Introduction

The chemistry of metal complexes with Schiff base ligands hasattracted sustained and extensive attentiondue to biologicalmodel-ing and applications, designing molecular ferromagnets, catalysis,liquid crystals and applications in the eld of optoelectronic tech-

method is the direct synthesis, which is based on the use of zerova-lent metals as starting materials, providing a suitable environmentfor the synthesis of different complexes of Cu(II). It has resulted asuitableway for preparing complexes of Cu(II) without residual salt.This is important in order to reach better conditions for crystalliza-tion process of the synthesized complex [811]. In this work, thea r t i c l e i n f oDepartamento de Fsica, ESFM, IPN, Av. InstitueCentro de Qumica, Instituto de Ciencias, Edif

h i g h l i g h t s

" [Cu(II)(saleanN3H3)] shows a interesti" 1D zigzag chains supramolecular stru" UVVis/IR spectra of [Cu(II)(saleanN3H" ESR at 300 K/77 K spectra and J value" The 1D chain magnetic model ts we0022-2860/$ - see front matter 2012 Elsevier B.V. Ahttp://dx.doi.org/10.1016/j.molstruc.2012.08.041eso S/N, Col. Trevio, Monterrey, NL 64570, Mexicocnico Nacional S/N, Edif 9, UP Zacatenco, Col. San Pedro Zacatenco, DF, Mxico 07738, Mexicomplejo de Ciencias, CU San Manuel, Puebla, Pue. 72570, Mexico

igzag chains supramolecular structure.rrelate well with the magnetic results.perfectly with the Cu(II) coordination.sistent with antiferromagnetic interaction.agnetic data of [Cu(II)(saleanN3H3)].Daniel Ramrez-Rosales , Jos Luis Alcntara-Flores , Yasmi Reyes-Ortegaa Facultad de Ciencias Fsico Matemticas, Universidad Autnoma de Puebla, CU San Manuel, Puebla, Pue. 72570, MexicoSynthesis, structural, electronic and mag

Ma. Guadalupe Quintero-Tllez a, Mara de Jess Rosd

Journal of Mol

journal homepage: www.ell rights reserved.tic studies of [Cu(II)(saleanN3H3)]

es Hoz b, Sylvain Berns c, Rafael Zamorano-Ulloa d,e,

SciVerse ScienceDirect

ular Structure

vier .com/ locate /molst ruc

then ltered. Light green single-crystals of [Cu(II) {N,N -bis(2-

Relevant crystallographic data of 1 are listed in Table 1. Addisonand co-workers [15] reported the trigonality index as s = (b a)/60 with a value of s = 1 when the structure is a perfect trigonalbipyramidal (tbp), and with a value of s = 0 when the structure is

Fig. 1. Molecular and crystal structures of 1. (a) ORTEP-like view of 1, withdisplacement ellipsoids for non-H atoms at 30% probability level. (b) View of thearrangement of molecules in the [100] direction, with intermolecular NAH Ohydrogen bonds and NAH p interactions represented as dashes lines. H atoms notinvolved in hydrogen bonding have been omitted for clarity.

Fig. 2. Crystal structure of 1 viewed down the [001] direction. All C-bonded Hatoms have been omitted for clarity, and dashed lines represent NAH Ointermolecular hydrogen bonds.

l ofoxybenzyl)-diethylenetriamine}] were obtained by crystallization(41.3 mg, 10%), mp 195 C (from MeOH). UVVis kmax/e (MeOH)nm/mM1cm1: 216/24569, 237/13593, 277/9145, 382/779, 598/156. IR mmax (KBr) cm1: 3303 (NH), 468 and 420 (CuN), 447(CuO). X-band ESR polycrystalline sample at 300/77 K g|| =2.1967/2.1967, g\ = 2.1074/2.1074; A77K/300K = 1.63; X-band ESRMeOH frozen-solution sample, ca = 17 mM g|| = 2.2153,g\ = 2.0563, A|| = 192.8 104 cm1. Mass spectrum (FAB+): m/z377 (M+, 45%).

2.3. Instruments

Melting point is obtained on a SEV melting point meter appara-tus. UVVis spectrum (1901100 nm) is recorded in a ShimadzuUV-3100S spectrophotometer in methanol solution for 1 of ca0.13 mM and 0.707 mM at 25 C, respectively. Calibration curvesat concentration used in this study and at kmax of 268 nm,378 nm and 600 nm show an absorbance-concentration linearrelation satisfying the LambertBeer law. IR spectrum (4000400 cm1) is obtained in a Nicolet Magna-IR 750 spectrophotome-ter using KBr pellet. The 1H NMR spectra is recorded at 25 C on aJEOL ECLIPSE 400 MHz spectrometer using methanol-d solutions inthe 100 to 100 ppm range. Powder X-band ESR spectra at 300 Kand 77 K and methanol solutions of 1 at four different concentra-tions ca from 17 mM to 41 mM are recorded on a JEOL JES-RES3X spectrometer. Magnetic measurement is recorded on a Quan-tum Design MPMS SQUID magnetometer from 2 K to 300 K.

2.4. X-ray crystallographic studies

A green crystal of 1with 0.32 0.15 0.1 mm3 size is mountedat random orientation on a glass ber. Data are collected on a En-rafNonius CCD diffractometer using MoKa radiation(k = 0.71073 ) at 295(2) K; programs used solve and rene thestructure: SHELXS-97 [14] and SHELXL-97. The structure of 1 issolved by direct methods and rened by full-matrix least squareson F2. Theta range for data collection 2.0427.49; reections col-lected 13550; independent reections 3591 [R(int) = 0.0618]; com-pleteness to theta = 27.49, 91.5%; zero restraints; absorptioncorrection: semi-empirical from equivalents. Max. and min. trans-mission: 0.95 and 0.74. H-atom parameters constrained. All Hatoms were placed in idealized positions, and were allowed to rideon their carrier atoms, with CAH bond lengths xed to 0.93 (aro-matic CH) and 0.97 (methylene CH2). The atomic coordinateshave been deposited with the Cambridge Crystallographic DataCentre. The coordinates can be obtained, on request from theDirector, Cambridge Crystallographic Data Centre, 12 Union Road,Cambridge CB2 1EZ, UK. Deposition number: CCDC 826049.

3. Results and discussion

3.1. Crystal structure

The neutral complex [Cu(II)(saleanN3H3)] 1 is built from oneunit of [saleanN3H3]2 where all heteroatoms of the base are coor-2.2. Synthesis

The copper complex has been prepared by direct synthesis[811]. Equimolar amounts (1.15 mmol) of copper and neutralbase saleanN3H5 in DMSO (3.7 ml) were placed in a ask and themixture was kept under magnetic stirring at 80 C for 26 h and

00

184 Ma. Guadalupe Quintero-Tllez et al. / Journadinated to the Cu(II) ion, which displays a highly distorted penta-coordinated structure, Fig. 1a. The packing index value for 1 is67.1% and the complex is isomorphous to the Zn(II) analogue [5].Molecular Structure 1034 (2013) 183188perfectly square pyramidal (sp). Molecular structure of 1 displayss = 0.51, in the middle of the two structures, tbp and sp, whichshows that 1 has a highly distorted structure.

(a) (b)

(c)

n

dd

d

d

330

nm

381

nm

237

nm

216

nm

627

nm

642

nm

695

nm

8 98

nm

x-y2 2

z2

xz, yz

xy

200 400 600 800 1000 (nm)

Abso

rban

ce

Abso

rban

ce600 750 900 1050

(nm)

0.12

0.06

0.00

3.0

1.5

0.00

Fig. 3. (a)UVVis spectrumof1. Inset shows the simulationof thedd transitionswiline) is offset by +0.005 absorbance units in order to match the simulated curve (das

Table 1Summary of crystal data, intensity data collection and structure renement of 1.

Empirical Formula CuC18H23N3O2

Formula weight 376.92Crystal system OrthorhombicSpace group PbcaCrystal size (mm3) 0.32 0.15 0.1Crystal color and shape Green blocka () 9.5603(6)b () 17.9503(13)c () 19.9588(16)Volume (3) 3425.0(4)Z 8q(calcd) (Mg/m3) 1.454F000 1576.0Theta range for data collection 2.04 to 27.49Temperature (K) 295(2)Reections collected 13550Independent reections 3591Rint 0.0618Parameters 221Goodness-of-t on F2 1.081Final R ndices [I>2sigmaI]a R1 = 0.0567, wR2 = 0.1307R indices (all data) R1 = 0.1290, wR2 = 0.1663

R1 P

jF0 jjFc jj jPjF0 j

, wR2 P

wF20F2c 2PwF20 2

r

Ma. Guadalupe Quintero-Tllez et al. / Jou al of Molecular Structure 1034 (2013) 183188 185rnth fourGaussian functions at kmax of 627, 642, 695and898 nm. Theexperimental curve (solidhed line). (b) Molecular orbital diagram corresponding to sp geometry. (c) IR spectrum of 1.

20406080100 0 -20 -40 -60 -80ppm

20 15 10 5 0 -5ppm

Fig. 4. 1H NMR spectrum of 1.

to occupy the equatorial positions and breaking the Benn rule[16]. Fig. 1a shows the ve-members CuN2C2 chelato ring highly

where emax is the molar absorptivity of the peak maximum and

The H NMR spectrum of 1 is typical of paramagnetic com-

rapecov

186 Ma. Guadalupe Quintero-Tllez et al. / Journal of Molecular Structure 1034 (2013) 183188distorted as reected in the torsion angles. One chelato ring formedby Cu1, N2, N3, C10 and C11 shows a torsion angle of 25.6(4),and the another chelato ring formed by Cu1, N1, N3, C8 and C9shows the torsion angle of 55.5(4).

Dipolar Coulomb interactions between mononuclear moleculesare observed through N(2)H(2A) O(2) and N(1)H(1A) O(1),forming regular chains in a 1D-supramolecular structure [17,18]with separations H(2A) O(2) of 1.892(3) and H(1A) O(1) of2.049(3) , Figs. 1b and 2. Theoretical investigations show thatthe hydrogen atoms play an essential structural role by holdingthese oxygen atoms in close proximity [19]. Other important inter-action, which produces a high stability for structure 1 is N3AH p-cloud of phenolato group Fig. 1b [19,20].

3.2. UVVis, IR spectroscopies

Fig. 3a shows the UVVis spectrum of 1 in solution with onebroad band which corresponds to dd transition at 600 nm. ThisThe apical bond distances values Cu(1)N(1) = 1.998(4) andCu(1)N(2) = 2.017(4) are shorter than the equatorial distancevalue Cu(1)N(3) = 2.217(4) , showing a less common Cu(II) axialcompression, bringing to the more electronegative oxygen groups

Fig. 5. One way of modeling the magnetic exchange interactions is to consider the tand angles in (bottom). A and A0 are dummy atoms placed on the centroids of nonband is consistent with that of other similar ve-coordinated Cu(II)compounds reported with sp geometry Fig. 3b [11,2127]. Spec-trum shows two bands of charge transfer transitions, one atkmax = 382 nm (e = 779 mM1 cm1) p? d ligandmetal transition,other at 330 nm d? p metalligand transition. At 216 nm(e = 24569 mM1 cm1) occurs the p? p transition, and at 237,277 nm (e = 13593, 9145 mM1 cm1) the n? p transitions, bothcharacteristic of saleanN3H5 [28]. Spectral data of 1 are summa-rized in Table 2 and shows molar absorptivity and oscillatorstrength values typical of transitions where parity forbidden La-porte selection rules are relaxed by lowered symmetry [2932].The dd band is satisfactorily tted with four Gaussian functions.Oscillator strengths, f, of each Gaussian band is calculated from

Table 2Assignments of the optical spectra of 1.

k(nm) Dm1/2(nm) e(cm2/mmol) f

627 102.69 26.82 1.269E-5642 326.32 80.42 1.209E-4695 179.31 41.28 3.412E-5898 239.53 24.20 2.672E-5pounds characterized by base line deformation due to the efcientnuclear relaxation of Cu(II) ions [11,35] The isotropic chemicalshifts observed in the spectrum are broadened either by the dipolarrelaxation of protons which are at 45 of the ion, and/or by thecontact relaxation of protons belonging to ligand residues withrelaxation times shorter than 5 ns [11,35,36]. Chemical shifts for1 appear from 100 to 100 ppm and it is not possible to quantifyand to assign the proton signals, Fig. 4.

3.4. Magnetic behaviorDm is half the intensity bandwidth [30,33]. The four Gaussianbands (Fig. 3a) have been assigned to the dx2y2 ! dz2 ; dxz; dyz; dxy,positive hole transitions for sp, and dx2y2 ! dxy; dz2 ; dxz; dyz positivehole transitions for tbp structure (Fig. 3b) [34]. Far IR spectrum of 1(Fig. 3c) shows saleanN3H5 typical vibrations m/cm1 1591 (C@C)and 3303 (NH) [26]. Metalligand vibrations are observed atm/cm1 447 (CuO), two bands 420 and 468 (CuN), in agreementwith the X-ray structure determination [10,11,19,34].

3.3. 1H NMR spectroscopy

1the relationship f = 4.325 109R e(m)dm 4.610 109emaxDm1/2;

zoid and triangles pathways along 1D-chains for 1. Separations are given in (top)alent intermolecular separations (N1 O1) and (N2 O2).The MYM bridging angle, h, with Y atom bridge, is a keystructural parameter. For h, the angles close to 90 or less favorminimum overlap, leading to ferromagnetic interactions owing toaccidental orthogonality of the orbitals [37]. For CuAOACu = h

0.20

0.10

0.00

0 100 200 300T (K)

1.0

0.8

0.6

0.4

M (em

u/m

ol)

MT

(emu K

/mol)

Fig. 6. Temperature dependence of vMT (h), vM (s), solid line is the best-ttingresults for linear chain for 1.

477 K

al ofangle the principal structural changes concern varies from 95.6 to104.1, antiferromagnetic behavior occurs to >104 [37,38]. Theantiferromagnetic behavior is expected for CuANACu for anglesbetween 97.5 and 108.5 [3941]. It has been proposed[37,40,42] that when the J values are plotted vs the ratio h/R, whereR is the distance from Cu to the bridging group, the h/R value of28.55 1 corresponds to a J maximum value. Hence, bridging an-gles close to 90 or less and h/R < 28.556 1 are taken as evidenceof ferromagnetism coupling.

Structural analysis of 1 shows that there are several magneticpathway types: CuAN OACu with irregular trapezium structureswith magnetic unit CuAN and CuAO; Cu OACu and CuN Cuas triangles magnetic structure pathways. In addition Fig. 5 shows

g = 2.1967

dpph

||

g = 2.1074

32H (kG)

77 K300 K

(a)

Fig. 7. (a) X-band ESR of polycrystalline sample of 1 at 300 K (dashed line) andconcentrations.

Ma. Guadalupe Quintero-Tllez et al. / Journthe bridging angles 101.3 and 108 for CuAOACu and 100.4 and107.9 for CuANACu (h/R = 2428 1) giving rise to the possibil-ity of antiferromagnetic or ferromagnetic exchange interaction[38,43,44]. Fig. 5 (top and bottom) shows in the middle of the linejoining atoms N O (point A) of the trapezium that there is an an-gle that there is an angle CuAAACu = h > 90, h/R > 28 1 (in facth/R around 43 1) indicating possibility of antiferromagnetic ex-change interactions[38,45,46].

The magnetic susceptibility of a polycrystalline sample of 1 ismeasured under an applied eld of 1 kOe, in the temperature range2300 K. Diamagnetic corrections were applied by using Pascalsconstants 149.61 106 emu/mol. 1 shows at room temperaturea vMT value of 1.06 emu K mol1, much higher than the value ex-pected for an isolated spin Cu(II) ion (for g = 2) for spin only para-magnets (0.374 emu K mol1), Fig. 6. When the temperature isdecreased gradually, the vMT values also decrease gradually; at2 K vMT is 0.415 emu K mol1. These two observations imply dom-inant antiferromagnetic interactions between copper centers. ThevT product of 1 shows no evidence of spincanting behavior, whichwould be manifested by a slight increase of vT at low temperature[47].

Analysis of the temperature variation of susceptibility with useof the CurieWeiss law yields a h value of 0.02 K (giso = 2.1372t), suggesting a very small exchange coupling constant [48]. FromX-rays results the distance Cu Cu is 5.016 for all Cu(II) mag-netic centers. The innite linear chain should be able to accountfor the observed susceptibility. The spin Hamiltonian adapted todescribe the isotropic interaction between nearest neighbor ionfor a magnetic chain of an array equally spaced Cu(II) ions isH^ JP SiSi1. The magnetic data have been analyzed using theEq. (1) as quadratic/cubic function [37]:

v Ng2b2

kTA Bx Cx2

D Ex Fx2 Gx3 1

where A = 0.25, B = 0.074975, C = 0.075235, D = 1.00, E = 0.9931,F = 0.172135, G = 0.757825, x = |J|/kT and J is the exchange couplingparameter describing the magnetic interaction between any twonearest neighbor S = 1/2 spins. The g-factor is tted to giso = 2.1372,the J value is -0.06868 cm1 with R = 1.41 102(R Pvobs vcalc2=Pv2obs). The small value of J is indicative ofa weak antiferromagnetism interaction; this result is in agreement

dpph

0 1 2 3 4 5H (kG)

g = 2.0563g = 2.2153||

A = 192.8x10 cm-4 -1||

(b)

c.a. = 40.78 mM

c.a. = 33.5 mM

c.a. = 16.98 mM

c.a. = 1.14 mM

c.a. = 0.1 mM

(solid line). (b) Hyperne splitting of 1 in frozen methanol solution at different

Molecular Structure 1034 (2013) 183188 187with the ESR result and the CurieWeiss adjustment [48].

3.5. ESR spectroscopy

X-band ESR spectra of polycrystalline sample of 1 were re-corded at 300 K and 77 K. The spectra show a broad (34.2 Gaussline width) singlet with the same values of g||(300 K) =g||(77 K) = 2.1967 and g\(300 K) = g\(77 K) = 2.1074 withouthyperne splitting, indicating exchange narrowing, Fig. 7a. Thepowdered sample of 1 does not show additional resonances atzero-eld or any other absorption at any gain. Hence, DMs = 2(Ms = double quantum spin ip), and zero-eld transitions do notoccur in this system [49]. The areas ratio value (arv) A77/300 =1.63 suggest an incomplete [50,51] antiferromagnetic behavior.Identical values of gs at 300 K and 77 K indicate that the atomic-magnetic structure is not signicantly modied with temperature.ESR spectra of 1 in frozen solution at different concentrations, ca0.1, 1.14, 16.98, 33.48, 40.78 mM, are carried out at 77 K, Fig. 7b.Hyperne splitting emerges when the magnetic exchangeinteractions disappear. The frozen solution spectra are rationalizedaccording to the simplied spin Hamiltonian H = g||bHzSz +g\b(HxSx + HySy) + A||SzIz + A\(SxIx + SyIy). Here all symbols havetheir usual meanings [33]. ESR of 1 in solution shows axial spectrawith g values of g|| = 2.2153, g\ = 2.0563, hyperne interactionwith A|| = 192.8 104 cm1 (186.4 G) and A\ (68.4 G) is notresolved in frozen solution. The two forms sp or tbp can berecognized from the ESR spectra, since g\ > g|| 2.00 and|A||| |A\| (60100) 104 cm1 for tbp and g|| > g\ and

|A\| g\ > 2.0023 indicatethat the unpaired electron is in the dx2y2 ground state [15,22,53],in accord with the UVVis spectrum. The electron congurationis characteristic of a sp or tbp local geometry around each Cu(II)ion.

4. Conclusions

We report the direct synthesis and the supramolecular crystal-line-structure network forming one-dimensional 1D columns of

[15] A.W. Addison, T.N. Rao, J. van Reedijk, J. Van Rijn, G.C. Verschoor, J. Chem. Soc.Dalton Trans. (1984) 1349.

[16] J.E. Huheey, E.A. Keiter, R.L. Keiter, Inorganic Chemistry: Principles of Structureand Reactivity, fourth ed., Harper Collins College Publishers, USA, 1993.

[17] B.K. Das, S.J. Bora, M. Chakrabortty, L. Kalita, R. Chakrabarty, R. Barman, J.Chem. Sci. 118 (2006) 487.

[18] D. Braga, F. Grepioni, Acc. Chem. Res. 33 (2000) 601.[19] C. Desplanches, E. Ruiz, A. Rodrguez-Fortea, S. Alvarez, J. Am. Chem. Soc. 124

(2002) 5197.[20] C. Bissantz, B. Kuhn, M. Stahl, J. Med. Chem. 53 (2010) 5061.[21] Y. Reyes-Ortega, J.L. Alcntara-Flores, M.C. Hernndez-Galindo, R. Gutirrez-

Prez, D. Ramrez-Rosales, S. Berns, B.M. Cabrera-Vivas, A. Durn-Hernndez,R. Zamorano-Ulloa, J. Mol. Struct. 788 (2006) 145.

[22] M. Du, Y.M. Guo, S.T. Chen, X.H. Bu, J. Mol. Struct. 641 (2002) 29.[23] E.T. Roth, Inorg. Chem. 46 (2007) 4362.

188 Ma. Guadalupe Quintero-Tllez et al. / Journal of Molecular Structure 1034 (2013) 183188Cu(II) ions in zigzag arrangement of 1. The UVVis study of 1 insolution is consistent with local coordination sphere, highly dis-torted between sp and tbp geometries, around Cu(II) ion shownby crystalline study. Magnetic results, ESR spectra of powder sam-ples of 1 and supramolecular structure are consistent with theweak antiferromagnetic constant value J obtained. In solution, 1is more stable in sp geometry according with UVVis and ESRstudies.

Acknowledgments

Yurij Mozharivskyj, Ph.D. Associate Professor of Chemistry,Department of Chemistry and Chemical Biology, Ontario, Canada,L8S 4M1, acknowledged for magnetization measurements. Presentwork has been supported by Secretara de Educacin Pblica, Sub-secretara de Educacin Superior, and Vicerrectora de Investiga-cin y Estudios de Posgrado from BUAP, Project No. REOM-NAT08/2009-G.

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Synthesis, structural, electronic and magnetic studies of [Cu(II)(saleanN3H3)]1 Introduction2 Experimental2.1 Materials and instrumentation2.2 Synthesis2.3 Instruments2.4 X-ray crystallographic studies

3 Results and discussion3.1 Crystal structure3.2 UVVis, IR spectroscopies3.3 1H NMR spectroscopy3.4 Magnetic behavior3.5 ESR spectroscopy

4 ConclusionsAcknowledgmentsReferences