788-791A few homo/hetero trinuc1ear complexes of the type [MNiM(BTDO)2X2(H2O)4] nH2O [where M = nickel(II), cobalt(II) and copper(II), X = cr or NO, n = 0, or 0.5 and BTDO = 1,8-bis(2'-oxophenyl)-2,3,6, 7-tetraza4,5-dimethyl-1 ,3,5,7-octatetraene] have been isolated in a stepwise reaction from the precursor nickel bis(diacetyldihydrazone) complexes. These have been characterised on the basis of elemental analyses, spectral and magnetic properties, conductivity measurements and thermal analyses. All the complexes contain coordinated water. The metal centres have an octahedral environmental around them

Mohanty, H

Panda, A K

Rout, S

English

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Indian Journal of ChemistryVol. 33A, August 1994, pp. 788-791Studies on some homo and hetero trinuclearcomplexes of nickel(II), cobalt(II) andcopper(II) with 1,8-bis(2' -oxophenyl)-2,3,6, 7-tetraza-4,5-dimethyl-l ,3,5,7-octatetraene (BTDO)A K Panda* & S RoutP G Department of ChemistrySambalpur University, Jyoti Vihar, Burla 768 019, OrissaandH MohantyLarambha College, Larambha 768 OJ 2Received 1 October 1993; revised and accepted 7 April 1994A few homojhetero trinuc1ear complexes of the type[MNiM(BTDOhXiH20)4] nH20 [where M = nickel(II),cobalt(II) and copper(II), X = cr or N03- ,n = 0, or 0.5and BTDO = 1,8-bis(2' -oxophenyl)-2,3,6, 7-tetraza-4,5-dimethyl-1 ,3,5, 7-octatetraene] have been isolated in astepwise reaction from the precursor nickelbis(diacetyldihydrazone) complexes. These have beench.iracterised on the basis of elemental analyses, spectraland magnetic properties, conductivity measurements andthermal analyses. All the complexes contain coordinatedwater. The metal centres have an octahedral environmentalaround them.The coordinated thio and phenyloxy groups havenon-bonding electron pairs which are sufficientlynucleophilic to form bridges with various metalions! -4. As a result, molecules such as bis(2-aminoethylene thio) nickel (II) and N,N' -ethylenebis(salicylidene iminate) metal [M Salen] [M =copper or nickel] can function as bidentate chelatingagents (metallo ligands) and form bi- and tri-nuclearcomplexes of the type (I) (M = Ni, Pd, Cd, Cu or Hg)and (II) (M = Ni or Cu, M' = Cu, Pe or Mil) as shownbelow.The metal complexes of dihydrazones of diacetyl,benzil and glyoxal have free amino groups suitablyoriented for condensation reaction. Suchmacrocyclic complexes with these metal complexeshave been reported by condensing the complex withformaldehyde':". However, no investigation has beenmade to increase the number of metal centresexploiting these amino groups. In this note we reportthe preparation and characterization of a fewhomo/hetero tri-nuclear complexes of thesedihydrazone complexes.IIExperimentalAll the chemicals used were of BDH or E Merckgrade. The solvents were distilled before use. All theother chemicals were used as such. Diacetyldi-hydrazone and its nickel complexes were preparedfollowing the literature method". Both homo- andhetero- nuclear complexes were prepared by thefollowing two methods.(i) The ethanolic solutions of bis(diacetyl-dihydrazone) nickel complex (0.5 mmol) andsalicylaldehyde (2 mmol) were retluxed for 2 h and tothe resulting solution was added ethanolic solutionsof metal salts of copper(IJ), nickel(II) and cobalt(II)(Immo!) dropwise. After refluxing for lh again, aclear solution was obtained. It was cooled to roomtemperature and a calculated amount of NaOH (2mmol) was added when an intense colouredprecipitate was obtained. It was filtered, washedseveral times with water followed by ethanol anddried over fused CaCho(ii) Hydrazine hydrate (2 mmol) and diacetyl(Immol) in ethanol were refluxed for 2h and whilerefluxing the nickel salts (0.5 mmol) in ethanol wereadded and the refluxing continued for another Ih. Itwas cooled to room temperature whereupon aprecipitate was obtained, which was filtered, washedseveral times with ethanol and dried over fused CaChoThe analytical data of this complex corresponds to thenickel bis(biacetyldihydrazone) complex as reportedby earlier workers 7•NOTES 789Table I-Analytical data of the complexesMol. Wt Found (Calc.), % AM IlerrFound mho ern- (B.M.)(Calc.) Ni Cu Co N'" C H CI mol-1Ni3(BTDOhCI24H2O 964 18.93 12.02 44.81 4.32 8.06 13 3.06(959) (18.35) (11.67) (45.84) (4.17) (7.40)Ni3(BTDOMN03h4H2O 1021 17.76 14.16 43.34 3.76 13 2.92(1012) (17.39) (13.83) (42.68) (3.95)NiCu2(BTDOhClz4.5HzO 974 5.92 13.42 12.26 43.42 4.58 7.76 18 5.13(978) (6.00) (13.00) (11.45) (44.17) (4.91) (7.25)NiCu2(BTDOMN03h4.5H20· 1036 5.76 12.83 13.95 41.81 4.17 II 4.98(1031 ) (5.69) (12.33) (13.57) (41.90) (3.97)NiCo2(BTDOhCI24H2O 963 6.35 12.77 12.05 45.16 4.02 7.71 16 5.39(960) (6.11) (12.29) (11.67) (45.01) (4.16) (7.39)NiCoiBTDOh(N03h4H2O 1023 5.97 12.36 14.23 43.05 3.92 14 5.26(1013) (5.79) (11.65) (13.82) (42.65) (3.94)*Induding nitrogen of nitrate groupSince the reaction product of diacetyl andhydrazine hydrate afford the metallo-ligands, we didnot isolate it from the reaction products. Afterrefluxing diacetyl and hydrazine hydrate in thepresence of nickel salt for 2h salicylaldehyde(4mmol) was added to the reaction mixture andrefluxing continued for another lh. On cooling, acalculated amount of NaOH was added. Theprecipitate was filtered, washed several times withwater followed by ethanol and finally dried over fusedCaCI2• The colour and composition of the complexesthus isolated corresponds to the complexes isolatedby method (i). The analytical data of the complexesare presented in Table 1.The metal and nitrogen content was estimated bythe known methods. Carbon and hydrogen wereestimated with a MLW-CHN micro analyser. Thereflectance and IR. spectra of the complexes wererecorded on a Cary 2390 and Perkin Elmer 983spectrophotometer respectively. The conductivitiesof the complexes in dioxane were measured with aToshniwal conductivity bridge. The roomtemperature magnetic moments were determined byGouy method with Hg[Co(NCS)4l as calibrant. Themolecular weight of the complexes were determinedby Rast's method.Results and discussionThe complexes are coloured and stable at roomtemperature. They are slowly attacked by dilute acids.They have high melting point (> 250°C) indicatingthese to be high molecular weight compounds. All thecomplexes are soluble in polar solvents such asdioxane, DMF and DMSO.The metallo schiff base ligand could not be isolated.Hence the spectra of the complexes are compared withthe spectra of the parent diacetyldihydrazone" andsome known salicylidene complexes". All thecomplexes exhibit an identical pattern suggestingthem to be isostructural.The IR spectra of the parent nickeldiacetyldihydrazone complexes undergo drasticchange after schiff base condensation reaction. Tnthehigh frequency region, the important characteristicfeature of the spectra is the absence of bands in theregion 3350-3200 em -1 and above 1700 em - 1indicating that condensation has taken place between- NH2 groups of hydrazone and the carbonyl groupof the salicylaldehyde.A broad band with its centre of gravity at ~3450 em -] indicates the presence of water molecules.The broadness of the band may be attributed to thepresence of strong inter/intramolecular hydrogenbonding. The next pair of bands which arc ofstructural significance are observed as a douhlet at "'"'1640and 1670em - 1. They can be assigned to vC = Nvibrations. The sharpness, intensity and the splittingof the band is probably due to the presence of twostructurally different C = N groups.Comparing the spectra of the earlier reporteddiacetyldihydrazone complexes, the band at the790 INDIAN J CHEM. SEe. A. AUGUSTlower frequency region (i.e. ~ 1640ern -I) is assignedto the azomethine group of the diacetyl fragmentwhile the band ,....,1670 cm - 1 correspond to theazomethine group from the salicylidene fragment.The former band in the free ligand(diacetyldihydrazone) was observed" at ~ 1580cm-Iwhich shifts to higher frequency region in the complexdue to participation of the d electron cloud from themetal centre into the ligand orbitals", therebyincreasing the degree of conjugation. As a result of thisinteraction, the bond order ofC = N group increases,shifting the C = N to higher frequency region. In thepresent complexes, they are shifted to still higherfrequency region ~ 1640 em - 1 indicating theelongation of conjugated system after condensationhas taken place. The splitting of the band to twofragments suggests that the azomethine groups are indifferent chemical environment.A band '"'-1480 em -1 attributed to vC-O suggeststhat deprotonation has taken place at the phenolicOH group of salicylaldehyde". The symmetric andasymmetric vC-CH, deformation vibrationundergo slight shift in their position, the mode of shiftbeing irregular.All the complexes have low molar conductancevalues and they also contain anions suggesting themto be coordinated (non-ionic) to the central metal ion.In order to confirm their nature (whether ionic ornon-ionic), the spectra of the nitrato complex wasrecorded. A nitrato group can act as a unidentate or abidentate ligand. The IR spectra of the nitratocomplexes exhibited two additional bands, one in theregion ~ 925-1050cm -1 (v.j and otherin the region~ 1290-1200 cm-1 (V2) which can be attributed tovN-O of NO; group. The third band (V3) which isexpected to appear for the N-O group in the region ~1530-1480em -1 appear to have been overlapped withthe deformation vibration of C-CH3 group. Bycomparing the spectra with some known unidentateand bidentate complexes'", weare of the opinion thatthe nitrate group is coordinated in a unidentatemanner in all the nitro complexes.The lower frequency region (600-200 em -I)furnishes information regarding the bonding in thecomplexes with respect to the ligand moiety. Thebands in the region ~ 530-510 cm - I and ~ 460-440cm -I are attributed to vM-O and vM-Nrespectively'J:'". Thus from IR spectral data, weconclude that the ligand molecule coordinates to themetal centres through azomethine nitrogens andphenolic oxygen. Comparing the spectral propertiesof the present series of the complexes with the nickelbis dihydrazone complexes, it seems that the anionsare coordinated probably to the central metal ion. Thephenolic OH group undergo deprotonation in thepresence of NaOH leaving the ligand as a dianion.Thus the charge on the metal centres are neutralised.Based on IR data, the following structure for thecomplexes can be proposed (structure III). It willsatisfy the electroneutrality of the complexes asindicated by conductivity measurement.IIISince IR spectra indicate the presence of watermolecules, we undertook thermal studies to ascertaintheir nature. The decomposition of the complexesfollow an identical pattern. There was no weight lossupto IQO°Cexcept for copper(II) complexes whichlose a mass corresponding to 0.5 molecule of water at~ 80°C. This is probably due to the presence oflatticewaterI3•14. After 160°C, the complexes lose weightcorresponding to four molecules of water in a singlestep supported by an exothermic peak at the sametemperature in the DT A thermogram. Such abehaviour is characteristic of the coordinated watermolecules in the same chemical environment. Thedecomposition proceeds slowly upto ~ 220°Cleaving behind a final residue at 780°C. The residuecorrespond to the formation of the respective metaloxides.The reflectance spectra of the complexes arecomplicated due to the overlapping of bandsbelonging to different metal ions and their presence indifferent crystal fields. However, we have madeattempts to identify some of these bands. Themagnetic moment values have been recorded in Table1. The spectra of parent? bis(diacetyldihydrazone)nickel(II) complex was compared with the spectra ofthe present series of complexes. The nickel(II) ion inbis(diacetyldihydrazone) nickel(II) is spin free typeand have an octahedral field around it. The spectralcharacteristics of the complex also suggests anoctahedral symmetry with certain degree oftetragonal distortion. It exhibits two bands in theregion 14000-19000 em - 1. The lower frequency bandcorresponds to 3Btg-+3 A2g and the higher frequencyband assigned to 3Btg-+3 Eg transitions respectively.The 3A2g and 3Eg transiuons are two splittingcomponents of 3T1g state of an octahedral field whensubjected to tetragonal distortion. These bandsundergo drastic changes when an in situ reaction wascarried out with the carbonyl compounds.All the [Ni3(BTDOhX24H20] complexes exhibitan identical pattern. The parent bands assigned to3BI~-+3 A2g and? Blg-+3 E~undergo a red shift and isobserved in the region 11,300-17,600 em -1. Thissuggests that the complexes have been subjected tostrong tetragonal distortion. The room temperaturemagnetic moment value per nickel ion is in the range2.92-3.06 B.M., which is less than the parentcomplex.All the [NiCu2(BTDO)zX24H20]0.5H20complexes exhibit an identical pattern with the bandsdue to parent bis(diacetyldihydrazone) nickel(II)complex getting broadened. A broad envelopcentered at 15,400 em - 1 and 22.200 em - 1 wereobserved. The former band is probably due to parentbis diacetyldihydrazone complex. The latter band canbe assigned to 2E~-+2 T2g transition due to copper(II)ion in an approximately octahedral field. The roomtemperature magnetic moment values lie in the range4.98-5.13 B.M.In case of [NiC02(BTDOhX24H20] complexes, nowell dissoluted bands were observed. Hence noassignment could be done. The magnetic momentvalues lie in the range 4.98-5.13 B.M. Therefore itseems that they are strong field complexes having twoparamagnetic cobalt centres.NOTES 791AcknowledgementWe gratefully acknowledge the fruitful discussionswith Prof. K C Satpathy Dept. of Chemistry,Sambalpur University. We also thank the authoritiesof RSIC, lIT Madras, for recording the IR andreflectance spectra of the complexes.ReferencesI Thanvasiri T & Sinn E, J chem Soc. (Dalton) (1989) 1187 andreferences therein, Mason M, Kand D, Chion L Kintz A &Blinn E L, J chem s«. Dalton (1987) 2599.2 Blinn E L, Bulter P, Chapman M M & Harris S, Inorg chim Acta.24 (1977) 139.3 De Sirnane R E. Ontko T, Wardman L & Blinn E L, lnorg Chern.14 (1975) 1313.4 Fenton D, Casella to U. Vigato P A & Vidali M. lnorg chimActa. 62 (1982) 57.5 Sahoo B, Rout A K & Sahoo B. Indian J Chern. 25A (1986)609.6 Mohapatra B K & Sahoo B, Indian J Chern. 22A (1983) 494 and23A (1984) 844, 24A (1985) ~53.7 Rai H C & Sahoo B. J Indian chem Sac UII (1976) 646.8 Stouffer R C & Busch D H. J Am chem Soc. 82.(1969) 3491.9 Satpathy K C, Panda A K. Mishra R & Panda I, Acta chimHung. 125 (1985) 527.10 Satpathy K C. Panda A K, Mishra R, Mishra P & Pradhan S K,J Indian chem Soc. 69 (1992) 119.II Satpathy K C. Panda A K, Mishra R, Mohapatra A & Patel A.Synth React Met-Org Chem, 22 (1992) 201.12 Satpathy K C. Jal B B& Mishra R. Indian J Chern. 24A (1987)147.13 Satpathy KC, Panda A K, Mishra R&Chopdar A P, Trans MetChern. 16 (1991) 628.14 Satpathy K C. Panda A K, Mishra R & Panda I, Trans MetChern. 16 (1991) 410.

Studies on some homo and hetero trinuclear complexes of nickel(II), cobalt(II) and copper(II) with 1,8-bis(2'-oxophenyl)2,3,6,7-tetraza-4,5-dimethyl-1,3,5,7-octatetraene (BTDO)

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Studies on some homo and hetero trinuclear complexes of nickel(II), cobalt(II) and copper(II) with 1,8-bis(2'-oxophenyl)2,3,6,7-tetraza-4,5-dimethyl-1,3,5,7-octatetraene (BTDO)

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