wdwith,, Fus and Scent of Opool of Na

ethylimidazole were synthesized. The complexes were characterized byFT-IR, Raman and PXRD techniques.

The complexes exhibit weaksemiconductive behavior.

eronuclear polymeric complexes M(II)/Ni(II) (M = Fe, Mn and Co) with 1-

Heteronuclear complexmodes of both theomplexes. Ttemperaturder X-ray a

revealed no signicant differences between the single crystal and powder forms. Additionally, eand magnetic properties of the complexes were investigated. The FT-IR and Raman spectroscopythermal and elemental analyses results propose that these complexes are similar in structureHofmann-type complexes.

2015 Elsevier B.V. All rights reserved.

Corresponding author. Tel.: +90 222 2393750; fax: +90 222 2393578.E-mail address: gkurkcuo@ogu.edu.tr (G.S. Krkoglu).

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 816

Contents lists available at ScienceDirect

Spectrochimica Acta Part A: Molecular andBiomolecular S

jouTetracyanonickelate(II) complex1-Ethylimidazole complexFT-IR and Raman spectraPowder XRD

spectra of the complexes were presented and discussed with respect to the internaletim and the cyanide ligands. The C, H and N analyses were carried out for all the cbehaviors of these complexes were followed using TG, DTG and DTA curves in the30700 C in the static air atmosphere. The FT-IR, Raman spectra, thermal and powhttp://dx.doi.org/10.1016/j.saa.2015.04.0191386-1425/ 2015 Elsevier B.V. All rights reserved.hermale rangenalyseslectrical, PXRD,to theArticle history:Received 5 November 2014Accepted 11 April 2015Available online 17 April 2015

Keywords:Cyanide-bridged complex

The heteronuclear tetracyanonickelate(II) complexes of the type [M(etim)Ni(CN)4]n (hereafter, abbrevi-ated as MNietim, M = Mn(II), Fe(II) or Co(II); etim = 1-ethylimidazole, C5H8N2) were prepared in pow-der form and characterized by FT-IR and Raman spectroscopy, powder X-ray diffraction (PXRD), thermal(TG; DTG and DTA), and elemental analysis techniques. The structures of these complexes were eluci-dated using vibrational spectra and powder X-ray diffraction patterns with the peak assignment to pro-vide a better understanding of the structures. It is shown that the spectra are consistent with a proposedcrystal structure for these compounds derived from powder X-ray diffraction measurements. Vibrationala r t i c l e i n f o a b s t r a c tethylimidazole were synthesized and characterized. The structures of these complexes were elucidatedusing vibrational spectra and powder X-ray diffraction patterns with the peak assignment to provide abetter understanding of the structures. New three cyanide complexes with 1- New cyanide-bridged hetVibrational spectra, poof cyanide complexes

Gnes Sheyla Krkoglu aa Eskisehir Osmangazi University, Faculty of ArtbAtasehir Adgzel Vocational School, DepartmcEskisehir Osmangazi University, Graduate Sch

h i g h l i g h t ser X-ray diffractions and physical properties1-ethylimidazole

lya etinkaya Kiraz b, Elvan Sayn c

iences, Department of Physics, TR-26480 Eskisehir, Turkeytician, TR-34779 _Istanbul, Turkeytural and Applied Sciences, Physics, TR-26480 Eskisehir, Turkey

g r a p h i c a l a b s t r a c t

rnal homepage: www.elsevier .com/locate /saapectroscopy

Introduction

The coordination chemistry of cyanide bridged metal complexesattracts interest because of their magnetic behavior, extraordinaryelectronic states and photochemical properties [13]. The cyanideion may coordinate either through the C atom, as a monodentate

water (10 mL) with potassium cyanide (4 mmol, KCN = 0.260 g) inwater (10 mL) solution. M[Ni(CN)4]H2O was prepared by mixingtogether the water solution of 1 mmol (0.258 g) K2[Ni(CN)4]H2O.To this K2[Ni(CN)4]H2O solution, 1 mmol metal(II) chloride(MnCl2 = 0.126 g, FeCl24H2O = 0.199 g or CoCl2 = 0.130 g) dissolvedinwater (10 mL)were addedwith continuous stirring approximately

The complexes obtained were performed elemental analyses.Elemental analyses were carried out on LECO, CHNS-932 analyzer

Vibrational spectroscopy

nd

G.S. Krkoglu et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 816 9ligand, or through the C and N atoms as a bridging ligand, formingpolymeric complexes with one-, two- or three-dimensional net-works. There is still much to be explored in the structures ofHofmann-type and its analogous that are built by the CN-bindingsamong square planar or tetrahedral tetracyanometallate(II) unitsand octahedral metal(II) units combined with auxiliary ligands [4].Hofmann-type complexes are determined by the general formula[ML2M0(CN)4] (M(II) = Mn, Fe, Co, Ni, Cu, Zn or Cd; M0(II) = Ni, Pdor Pt; L = unidentate ligand). The structures of these complexes con-sist of two-dimensional polymeric layers formed from [ML2]2+

cations and [M0(CN)4]2 anions. The M0 atom is coordinated to fourC atoms of the CN groups forming a square-planar geometry. TheM(II) ion is octahedrally surrounded by six N atoms, four fromthe CN units and the other two are from two ligand molecules.The ligand molecules are located above and below the layers. Theligands and the layers as blocking units provide voids of varyingshapes and dimensions, in which guest molecules may be conned[4]. Similar to this structure, several metal tetracyanonickelate(II)complexes with regard to Hofmann-type host have been improvedby using N-donor ligands [512].

Metal complexes containing imidazole-based ligands are sub-ject of intensive researches due to their rich coordination chem-istry and a number of installed potential application areas [1315].

Recently, we have synthesized heteronuclear polymeric com-plexes with cyanide and 1-ethylimidazole ligands [1618]. In ourprevious work [17], we reported that the FT-IR, Raman spectra, ther-mal property and crystal structure results of tetracyanonickelate(II)complexes with 1-ethylimidazole (etim). As a part of an ongoingresearch project dealing with the coordination chemistry of cyanideand 1-ethylimidazole ligands, herein we report the results of ourstudy on the preparation, vibrational spectra, powder X-ray diffrac-tions and thermal properties of three new heteronucleartetracyanonickelate(II) complexes, namely, [Mn(etim)Ni(CN)4]n,{[Fe(etim)Ni(CN)4]2H2O}n and [Co(etim)Ni(CN)4]n. In addition tothe structural analysis of the complexes were also measured electri-cal conductivity and magnetic susceptibility.

Experimental

Materials

All materials such as manganese(II) chloride (MnCl2, 96%),iron(II) chloride tetrahydrate (FeCl24H2O, 99%), cobalt(II) chloride(CoCl2, 99%), potassium cyanide (KCN, 96%) and 1-ethylimidazole(C5H8N2, 95%) were purchased from commercial sources and usedwithout further purication.

Syntheses of the complexes

K2[Ni(CN)4]H2Owas prepared bymixing stoichiometric amountsnickel(II) chloride hexahydrate (1 mmol, NiCl26H2O = 0.238 g) inTable 1Elemental analyses of the complexes.

Complex Mwt. (g/mol) Elemental analyses

C%

Calc. Fou[Mn(C5H8N2)Ni(CN)4]n 313.83 35.74 34.44{[Fe(C5H8N2)Ni(CN)4]2H2O}n 350.77 31.34 30.82[Co(C5H8N2)Ni(CN)4]n 317.83 35.28 34.011-Ethylimidazole vibrationsThe FT-IR and Raman spectra of the complexes are shown in

Figs. 13, respectively. Additionally, the assignments of thewavenumbers of the etim molecule observed in the FT-IR andRaman spectra of the complexes are given in Table 2, togetherwith the wavenumbers for etim and complex [Ni(etim)4Ni(l-CN)2(CN)2]n [17]. As shown from Table 2, considerable shifts to

Color

H% N%

Calc. Found Calc. Found

2.92 2.57 25.83 26.78 Whitefor C, H and N at the Middle East Technical University CentralLaboratory. Elemental analyses are in good agreement with the cal-culated values which are given in Table 1. FT-IR and Raman spectraof the complexes were recorded in the region of 4000250 cm1

via Perkin-Elmer FT-IR 100 spectrometer at a resolution of4 cm1 and Bruker Senterra Dispersive Raman Microscope usingthe 785 nm line of a 3B diode laser, respectively. Perkin ElmerDiamond TG/DTA thermal analyzer was used to record simultane-ous TG, DTG and DTA curves in the static air atmosphere at a heat-ing rate of 10 K min1 in the temperature range of 30700 C usingplatinum crucibles. The XRD patterns of the powder products wereobtained on a Rigaku Rint 2200 diffractometer using Cu-Ka radia-tion. The samples were loaded in a 0.3 mm glass capillary, whichwere rotated during the data collection. Electrical conductivitywith four-probe technique was measured using Keithley 2601 ASystem Sourcemeter four terminal conductometer. The two oppo-site surfaces of the pellet were coated, under pressure, with a mix-ture of the material and iodine powder in the weight ratio 3:1.Contacts were glued to the complexes with a graphite paste using1020 lm diameter platinum wire. Applied current was 1020 lA.Magnetic susceptibility was measured using Sherwood ScienticMagnetic susceptibility balance (MSB) MX I Model. The MSBMark I or Evans magnetic balance is designed as a reverse tradi-tional Gouy magnetic balance.

Results and discussionfor 4 h at 50 C in a temperature-controlled bath. The compoundswere ltered and washed with water and dried in open air. To this1 mmol of M[Ni(CN)4]H2O (M = 0.236 g for Mn(II), 0.236 g for Fe(II)and 0.240 g for Co(II)) water solution, 4 mmol (0.385 g) of etim dis-solved in ethyl alcohol (10 mL) was added a few drops to resultingsolution with continuous stirring approximately for 5 h at 60 C in atemperature-controlled bath and then ltered, washed with water,ethanol, and ether, respectively, and dried at room temperature.

Physical measurements3.45 3.45 22.19 23.96 Orange2.83 2.54 25.55 26.44 Pink

lecu10 G.S. Krkoglu et al. / Spectrochimica Acta Part A: Mohigher or lower wavenumber occur in the presence of numerousabsorption bands in the spectra of all complexes.

The absorption bands are observed in the region from3588 cm1 to 3446 cm1 due to the symmetric and asymmetricm(OH) stretching vibrations of the water molecules [17].Moreover, the presence of water molecules manifests itself at

Fig. 1. The FT-IR (a) and Raman (b) slar and Biomolecular Spectroscopy 149 (2015) 816about 1650 cm1 and 1620 cm1 due to d(OH) deformation vibra-tions [19]. In FT-IR spectra of FeNietim, the absorption band at3489 cm1 may be attributed to the asymmetric and symmetricm(OH) stretching mode of water molecules. Furthermore, d(OH)deformation vibrations belonging to OH bending modes wasobserved at 1639 cm1. The shift to lower frequencies of these

pectra of MnNietim complex.

olecuG.S. Krkoglu et al. / Spectrochimica Acta Part A: Mstretching modes and the shift to higher frequencies of the bendingmodes may be connected to the hydrogen bonding in the complex.These bands were not observed MnNietim and CoNietimcomplexes.

As evident from Table 2, in the FT-IR and Raman spectra of thecomplexes, the observed bands at 3152 and 3122 cm1 forMnNietim, at 3154 and 3122 cm1 for FeNietim, at 3157 and3122 cm1 for CoNietim can be assigned to the characteristicimidazole ring CH symmetric and antisymmetric stretchingmodes, respectively. The absorption bands of the m(CH3) andm(CH2) groups in the complexes are observed in the frequencyrange of 30022887 cm1, and signicantly shifted to loweror higher frequencies compared to the free ligand. The

Fig. 2. The FT-IR (a) and Raman (b) slar and Biomolecular Spectroscopy 149 (2015) 816 1117001200 cm1 frequency range is mainly characteristic forantisymmetric and symmetric, C@C and C@N, stretching vibrationsof the imidazole ring as well as various CH bond deformations.When the aromatic ring nitrogen involves in the complex forma-tion, the certain ring modes, particularly the modes in the regionof 16001400 cm1 increase in value both due to the coupling withMN(ligand) bond vibrations and due to the alterations of the ringforce. The CH bond deformation vibrational modes of the etim canbe observed in the 14601400 cm1 region of the spectra, the1200900 cm1 region is dominated by the CC stretches, CHdeformation vibrations as well as by the ring vibrations. The spec-tral features and assignments of the other vibrations are includedin Table 2.

pectra of FeNietim complex.

lecu12 G.S. Krkoglu et al. / Spectrochimica Acta Part A: MoNi(CN)4 group vibrationsThe most important aspects of the FT-IR and Raman spectra of

the complexes, involve the characteristic vibrations of m(CN). Inthe spectra of the complexes, the dominant feature is representedby strong and sharp well identiable absorption bands, due to them(CN) stretching vibrations [20]. The [Ni(CN)4]2 anion possessesideally D4h symmetry and, thus, will have 16 fundamental vibra-tions (2A1g, 1A2g, 2B1g, 2B2g, 1Eg, 2A2u, 2B2u, and 4Eu) [21]. Of these,A2u and Eu are infrared active, while A1g, B1g, B2g, and Eg are Ramanactive. The A2g and B2u vibrations are inactive. No B2g modes wereobserved. The m(CN) vibrations are the most important absorp-tion bands for the complexes. The vibrational wavenumbers of

Fig. 3. The FT-IR (a) and Raman (b) slar and Biomolecular Spectroscopy 149 (2015) 816[Ni(CN)4]2 group for the K2[Ni(CN)4]H2O and all complexes arepresented in Table 3, together with vibrational assignments of[Ni(CN)4]2 [22].

The characteristic bands in the FT-IR and Raman spectra ofmetal complexes containing cyanide are sharp and strong between2000 and 2200 cm1 resulting from m(CN). The m(CN) modes areobserved at 2151 cm1 for MnNietim, 2155 cm1 FeNietim,and 2158 cm1 CoNietim in the FT-IR spectra. Seven Ramanactive modes are expected in the same region, but only two ofthese, the m(CN) modes (2176 and 2122 cm1 for MnNietim,2177 and 2135 cm1 for FeNietim and, 2182 and 2138 cm1

for CoNietim) are observed in the complexes on which Raman

pectra of CoNietim complex.

olecuTable 2The vibration wavenumbers of etim in the complexes (cm1).

Assignments [29] etim (liquid) NiNietim [17]

FT-IR Raman

ms(CH) of CH@CH 3134 sh 3140 sh 3155 mmas(CH) of CH@CH 3107 m 3129 m 3135 mmas(CH3), mas(CH2) 2981 s 2971 m 2974 mms(CH3), ms(CH2) 2940 m 2943 m 2948 mms(CH2) 2889 w 2903 w 2929 wm(C@C) m(C@N) 1676 w 1681 sh m(R), combination 1596 w 1591 m

G.S. Krkoglu et al. / Spectrochimica Acta Part A: Mexperiments were made. m(CN) and d(NiCN) are both strong sharpbands in the FT-IR spectra of the complexes. m(CN) is shiftedupwards by about 30 cm1 compared to the same frequency inthe K2Ni(CN)4 complex. d(Ni-CN) is shifted upwards much less.These frequencies of both bands are dependent on the metal. Them(NiC) stretching vibration is observed as a broad, weak bandaround 540 cm1 and this vibration shows a small metal depen-dence. The out-of-plane p(NiCN) mode is only observed weaklyin the complexes. As can be seen from Table 3, m(CN) frequenciesare metal dependent and increase in the order Mn < Fe < Co. Intetracyanonickelate(II) complexes, mechanical coupling betweenthe m(CN) stretching mode and m(NiC) modes is well known[23]. Therefore, the metal dependence of the m(CN) wavenumbers

1510 vs 1524 s 1530 mdas(CH2)scis 1465 m 1468 m 1460 wdas(CH3)scis 1448 m 1449 m 1419 wm(R), combination 1394 m d(CH), m(R) 1385 m 1377 m

1355 m 1359 m 1356 mm(R), d(CH2)twist 1287 m 1290 m 1294 wCombination 1250 w 1252 m

1228 vs 1235 s 1245 wq(CH3), q(CH2), m(R) combination 1194 sh

1110 s 1109 s 1105 m1078 vs 1090 s

d(R) 1034 m 1036 m 1048 mc(CH) 958 m 955 m 967 m

908 s c(CH), m(CC) 875 sh 852 m 864 vw

819 s 829 s 742 s 742 s 770 vw

m(CH2N), m(CCH2) 667 vs 658 m 663 wd(CH) 624 m 620 m d(CH2), m(CC) 515 vw

Abbreviations used: m stretching, d deformation, c wagging, t twisting, r rocking, s stron

Table 3The wavenumbers of the [Ni(CN)4]2 and metalligand vibrations in the complexes (cm1

Assignments [22] K2[Ni(CN)4]H2O NiNietim [17]A1g, m(CN) (2160)vs (2179)vsB1g, m(CN) (2137)m (2142)wEu, m(CN) 2122 vs 2155 vs, 2120 sEu, m(13CN) 2084 w 2079 wEu, m(NiC) 540 w 541 wA2u,p(NiCN) 443 w 449 wEu, d(NiCN) 417 s 425 sA1g, m(NiC) (374) (376) wEg, p(NiCN) (298) (344) wB2g, d(CNiC) (109)

Metalligand vibrations [30]A2u,m(MN)(etim) 369 wEu, m(MN)(CN)4 289 wA1g/Eg, m(MN)(etim) (261) wA2u, d(NMN)(etim) Eu, d(NMN)(CN)4

Abbreviations used: s strong, m medium, w weak, sh shoulder, br broad, v very. Trespectively.MnNietim FeNietim CoNietim

FT-IR Raman FT-IR Raman FT-IR Raman

3152 m 3159 m 3154 m 3161 m 3157 m 3160 m3122 m 3133 m 3122 m 3138 w 3122 m 3132 m2989 m 3002 m 2989 m 2999 m 2989 m 2984 m2942 m 2953 m 2943 m 2950 m 2942 m 2952 m2891 w 2898 w 2890 w 2887 w 2892 w 2894 w1682 w 1687 vw 1683 w 1697 vw 1684 w 1697 vw1596 w 1545 w 1597 m 1543 vw 1596 m 1542 m

lar and Biomolecular Spectroscopy 149 (2015) 816 13reects the strength of the metal anion bond, MN(NC) [23].Such frequency shifts have been observed for other Hofmann-typeclathrates [512] and Hofmann-type complexes [23,30].

Metal-ligand vibrationsThe FT-IR spectra of the complexes showed a group of new

bands with different intensities which characteristics for m(MN).The m(MN) stretching and d(NMN) bending bands in the far infra-red region enable the information about the structure of themetalligand. m(MN) stretching vibrations of 16 imidazole com-plexes of Ni(II), Cu(II), Zn(II), and Co(II) were observed in the325210 cm1 region [21]. The m(MN) stretching bands wereobserved at 367 and 281 cm1 for MnNietim, at 368 and

1512 s 1513 s 1513 vw 1514 s 1470 m 1470 m 1470 m 1475 w 1471 m 1469 w1458 m 1423 w 1459 m 1427 w 1459 m 1423 w1397 m 1398 m 1395 vw 1398 m 1377 m 1376 m 1375 m 1355 m 1354 w 1355 w 1359 m 1358 w1288 vw 1289 w 1297 vw 1288 vw 1299 vw1258 w 1258 w 1257 w 1257 w 1267 vw1240 s 1241 s 1248 vw 1242 s 1136 w 1136 w 1137 sh 1137 vw 1137 sh 1137 w1121 s 1122 s 1121 s 1087 s 1100 m 1088 s 1103 w 1088 s 1100 m1038 m 1054 w 1037 m 1050 w 1037 m 1053 w968 w 968 w 970 w 969 w 983 w 911 vw 914 vw850 w 862 vw 850 w 863 vw 850 w 864 vw832 s 833 s 834 s 747 s 757 vw 747 s 756 vw 747 s 754 vw660 s 667 m 661 s 669 w 661 s 665 w616 m 617 m 628 vw 617 m 622 w526 vw 530 vw 525 vw

g, m medium, w weak, sh shoulder, v very.

).

MnNietim FeNietim CoNietim

(2176)vs (2177)vs (2182)vs(2122)w (2135)w (2138)w2151 vs 2155 vs 2158 vs2111 w 2114 w 2116 w543 w 544 vw453 vw 455 vw 457 vw427 s 431 s 432 s(378) w (376) w (376) vw(349) w (342) vw (343) w

367 w 368 vw 362 w281 w 278 w 285 vw(259) w (260) vw (250) vw

he symbols m, d, and p refer to valence, in-plane and out-of-plane vibrations,

lecu14 G.S. Krkoglu et al. / Spectrochimica Acta Part A: Mo278 cm1 for FeNietim, at 362 and 285 cm1 for CoNietim, at369 and 289 cm1 for NiNietim in the FT-IR spectra. The samebands were found at 261 cm1 for NiNietim, at 259 cm1 forMnNietim, at 260 cm1 for FeNietim, at 250 cm1 for CoNietim in the Raman spectra. d(NMN) bending bands were notobserved for spectra taken up to 250 cm1.

Fig. 4. The powder X-ray diffraction patterns of the complexes (a) M

Fig. 5. The molecular structure of complex NiNietim complex [17].lar and Biomolecular Spectroscopy 149 (2015) 816Powder X-ray diffraction

Single crystal X-ray diffraction method could not be used, dueto poor single crystal quality. Thats why, powder X-ray diffractionand energy minimization methods were used to predict threedimensional molecular geometries of the complexes. The powderdiffraction patterns of the four compounds are shown in Fig. 4.As a result of energy minimization studies three main atomicplanes were obtained. The diffractogram of complexes exhibitsintense peaks.

In previous study [17], NiNietim complex was obtained as asingle crystal (Fig. 5). NiNietim complex obtained as single crys-tal was also examined by PXRD in this study, and the structure ofNiNietim complex was compared with other complexes.

Magnetic properties

The magnetic susceptibility of the complexes was determinedby Evans Method. The complexes exhibit paramagnetic behavior.Since the Ni(II) atom in the [Ni(CN)4] unit remains in diamagneticstate, these results are conclusive evidence on the high spin statefor the four metals (Mn, Fe, Co, Ni). In Table 4, the values for theeffective magnetic moment (leff) at room temperature, calculatedfrom the magnetic susceptibility are summarized.

MnNietim complex exhibits a magnetic moment value of5.57 BM, which corresponds to ve of unpaired electrons perMn(II) ion. This value is considerably lower than the spin-onlyvalue of 5.92 BM, expected for high-spin Mn(II). The magneticvalue of CoNietim complex at room temperature is 4.12 BM,which is higher than the calculated spin-only value of 3.87.

nNi-etim; (b) FeNietim; (c) CoNietim; (d) NiNietim.

ected value [31]in + orbital)

Expected value [31](spin only)

Unpaired electrons

0 5.92 5 e

5.5 4.90 4 e

5.2 3.87 3 e

4.0 2.83 2 e

olecuHowever, it agrees with the values observed for octahedral Co(II)complexes with a signicant rst-order orbital contribution to onlya spin magnetic moment. FeNietim complex exhibits magneticmoment value of 4.68 BM, which correspond to four unpaired elec-tron of the Fe(II) ion, respectively. This value is close to the spin-only value of 4.90. NiNietim complex exhibit magnetic momentvalues of 3.04 BM which both correspond to paramagneticwith two unpaired electrons. Compare the experimental valueswith the theoretical values of complexes we can say thatthey have paramagnetic properties [24]. The complexes have asimilar measurement to the previously reported 5.04 BM inCo(EtIm)2[Ni(CN)4] and 2.97 BM in Ni(EtIm)2[Ni(CN)4] (EtIm = 2-ethylimidazole) [25], 4.59 BM in Fe(Im)2[Ni(CN)4], 5.18 BMCo(Im)2[Ni(CN)4] and 3.24 BM Co(Im)2[Ni(CN)4] (Im = Imidazole)[26].

Electrical measurements

All products produced by the reaction with the solution ofiodine MNietim complexes exhibited a higher value of the elec-trical conductivity over the whole range of frequencies used (10105 Hz, at 25 C). The conductivity of compounds was measuredby the standard four-point probe method in the dc plane. The con-ductivities at room temperature were found to be2.596 108X1 cm1 for MnNietim, 2.047 108X1 cm1for FeNietim, 1.137 107X1 cm1 for CoNietim and1.923 109X1 cm1 for NiNietim. The conductivity valuesof the complexes are a like each other and rather high in spite ofthe measurements on the powder compressed pellets. The electri-cal conduction properties of several examples of these types ofcomplexes have been studied [27,28] and they have been foundto behave as semiconductors with the conductivity in the directionof the metal atom chain ranging from 107 to 1010X1 cm1 atroom temperature. The complexes show very weak semiconductor.

Thermal analyses of the complexes

Thermal behaviors of the complexes were studied by TG, DTGand DTA curves in the temperature range 30700 C in the staticair atmosphere. Thermal decomposition curves of the complexesare presented in the labels of Fig. 6.

The complexes are thermally stable up to 118 C for MnNietim, 138 C for FeNietim and 137 C for CoNietim and the

Table 4Magnetic susceptibilities at room temperature of the complexes.

Complex Experimental values Exp(sp

[Mn(C5H8N2)Ni(CN)4]n 5.57 5.9{[Fe(C5H8N2)Ni(CN)4]2H2O}n 4.68 5.1[Co(C5H8N2)Ni(CN)4]n 4.12 4.1[Ni(C5H8N2)4Ni(CN)4]n 3.04 2.8

G.S. Krkoglu et al. / Spectrochimica Acta Part A: Mcomplexes show two stage mass loss (Fig. 6). The MnNietimand CoNietim complexes followed usual decomposition mecha-nism in which neutral ligand (etim) is released rst stage. The FeNietim complex followed usual decomposition mechanism inwhich two water molecules and etim ligand are released rststage. In the second stage, cyanide ligands in the complexes aredecomposed. The stage between 118 and 407 C for MnNietim,138 and 385 C for FeNietim and 137 and 413 C for CoNietim corresponds to the exothermic peak on the DTA curve(DTAmax = 401 C in MnNietim, 365 C in FeNietim and395 C in CoNietim). This peak is associated with the decompo-sition and burning of the cyanide ligands. The nal decompositionproducts are found to be the corresponding metal oxides. Thelar and Biomolecular Spectroscopy 149 (2015) 816 15thermal decomposition products were identied as MnO and NiOwith a mass loss of 43.20% (calcd. 46.40%) for MnNietim, asFeO and NiO with a mass loss of 43.20% (calcd. 47.07%) in

Fig. 6. TG, DTG and DTA curves of (a)MnNietim, (b) FeNietim and (c) CoNietim.

FeNietim and as CoO and NiO with a mass loss of 44.52% (calcd.47.07%) in CoNietim.

Conclusion

The present paper is a part of our investigations on the struc-tures and physical properties of heterometallic cyanide complexeswith 1-ethylimidazole. We have synthesized and characterized the

host-aromatic guest systems, J. Inclusion Phenom. Macrocyclic Chem. 45 (2003)129137.

[10] G.S. Krkoglu, O.Z. Yesilel, _I. Kavlak, O. Bykgngr, Nickel(II) pinteraction in [M(ampy)2Ni(l-CN)2(CN)2]n (M = Zn(II) and Cd(II), ampy = 2-aminomethylpyridine): syntheses, vibrational spectroscopy, thermal analysesand crystal structures of cyano-bridged heteronuclear polymeric complexes, J.Mol. Struct. 920 (2009) 220226.

[11] G.S. Krkoglu, Vibrational spectroscopic studies of some dimethylpyrazinecadmium(II) tetracyanonickelate benzene clathrates: [Cd(C6H8N2)Ni(CN)4]C6H6, J. Inclusion Phenom. Macrocyclic Chem. 67 (2010) 191200.

[12] G.S. Krkoglu, _I. Kavlak, _I. ayl, Infrared and Raman spectroscopic studies of

16 G.S. Krkoglu et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 816three new heterometallic cyanide complexes [Mn(etim)Ni(CN)4]n,{[Fe(etim)Ni(CN)4]2H2O}n and [Co(etim)Ni(CN)4]n. On the basisof the vibrational (FT-IR and Raman) spectroscopic results, we pro-pose that in the case of the complexes the etim molecule are coor-dinated to M(II) (M = Mn, Fe and Co) ions of the adjacent layers of[M-Ni(CN)4]n. For a given series of isomorphous complexes, theeffects of metal ligand bond formation on the ligand vibrationalmodes are examined. The complexes showed a moderate conduc-tivity of 108X1 cm1 at room temperature. These results suggestthat cyanide complexes with stronger donor ability may give newcomplexes having electrically and magnetically intriguingproperties.

Acknowledgement

This paper is dedicated to Prof. Dr. Ziya KANTARCI, who died onJanuary, 2012.

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Vibrational spectra, powder X-ray diffractions and physical properties of cyanide complexes with 1-ethylimidazoleIntroductionExperimentalMaterialsSyntheses of the complexesPhysical measurements

Results and discussionVibrational spectroscopy1-Ethylimidazole vibrationsNi(CN)4 group vibrationsMetal-ligand vibrations

Powder X-ray diffractionMagnetic propertiesElectrical measurementsThermal analyses of the complexes

ConclusionAcknowledgementReferences