Indian Journal of ChemistryYol. 21A, August 1982, pp. 825-826

Polymeric Complexes of Copper(II),Nicke1(II) & Cobalt(Il) with Semicarbazonesof 2,5-Dihydroxyacetophenone, 2,5-Dihydroxypropiophenone & 2,5-Dihydroxy-

benzophenone

J K YERMA*

Govt. College, Daman 396210

and

G S P YERMA

Ranchi University, Ranchi 834008

Received 23 October 1981; revised and accepted 29 March 1982

Complexes of Cu(l!), Ni(II) and Co(ll) with semicarbazonederivatives of 2,5-dihydroxyacetophenone, 2,5-dihydroxypropio-phenone and 2,5-dihydroxybenzophenone have been prepared andcharacterised. The analytical data show I: I (metal-ligand)stoichiometry. The TGA and DTA data indicate the presence of twocoordinated water molecules suggesting a general formulaMSB.2H20. The IR spectral data reveal that both the phenolicprotons are lost during complex formation leading to coordinationpolymerisation. The ligands arc coordinated through azomethinenitrogen and carbonyl oxygen. The magnetic and electronic spectraldata suggest octahedral geometry for the complexes.

Maurya et al,' have observed that the salicylaldehydesemicarbazone forms 1:2 monomeric complexes withCu(II), Ni(II) and Co(II) ions. Arora et al. Z havereported that acetophenone semicarbazone formspolymeric complexes with Ni(ll) in which the ligand isbonded through oxygen of C =0 and nitrogen of C= N. The present note deals with the synthesis andcharacterization of the title complexes.

2,5-Dihydroxy-acetophenone,-propiophenone and-benzophenone were prepared by the method reportedearlier:'. The corresponding semicarbazones wereprepared by the conventional method". These gavesatisfactory elemental analyses. The solution ofsemicarbazone(O.OI mol) prepared in DMF was addedto the metal salt solution (0.0 I mol; 2.0 g ofCuAcz.HzO; 2.48 g of NiAcz.4HzO; or 2.48 gCoAcz.4HzO) with constant stirring. The reactionmixture in each case was stirred for 30 min. The pH ofthe mixture was adjusted to 6-7 by sodium acetate-acetic acid buffer and then it was retluxed over a water-bath for 2 hr and finally left overnight. The solid thusseparated was washed with ethanol and dried overfused CaCI2 in oacuo, The compounds (Table I) couldnot be recrystallised due to their insolubility in almostall the common organic solvents.

The metals were estimated by EDT A titration" afterdecomposing the complexes by perchloric acid.

Nitrogen was estimated by Duma's method. Themolecular weight determination by cryoscopic methodusing camphor as the solvent did not give reproducibleresults. Conductances of the complexes were measuredin DMF on a Toshniwal conductivity bridge. TheDT A studies were carried out on a Schreiber 0517instrument and TGA on a Cambridge Clearspan P250thermo balance. The magnetic moments of the solidcomplexes were determined at room temperature on aGouy balance. The absorption spectra were recordedon a spectronic-20 spectrophotometer. Infraredspectra were recorded in KBr phase with the aid of aPerkin-Elmer spectrophotometer in the range 4000-200cm -.1.

The analytical data indicate I: I (metal-ligand)composition. The low molar conductance values (4.8-6.2 mhos em? mol -1) of the complexes are ascribed totheir non-electrolytic nature. The insolubility of thecomplexes in common organic solvents indicates theirpolymeric nature. The endothermic peaks observedbetween 180' and 220' in the DT A curves suggest thepresence of the coordinated water. The TGA studiesreveal that the weight loss upto 180°,2300 and 210°Cfor Cu(II), Ni(I1) and Co(II) complexes respectivelycorresponds to two water molecules suggesting ageneral formula MSB.2HzO for the complexes. Thecomplete decomposition takes place in the range 580-

Table l--Analytical, Thermal and Conductance DataComplexes Found (Calc.), ,%"Colour

Metal N TGAwtloss"

CuSB12H2O Parrot -green 20.65 15.52 11.62(20.73) (15.66) (11.74)

CuSB22H2O Light-green 19.76 14.84 Il.3S(19.82) (14.98) (1123)

CuSB32H2O Light-green 17.34 13.15 9.63(1722) (13.03) (9.75)

NiSBj2H2O Sky-blue 19.58 15.82 11.82(19.45) (15.91) (11.93)

NiSB22HzO Sea-green 18.48 15.32 1l.32(18.60) (15.21) (11.40)

NiSB32HzO Green 16.23 13.29 10.24( 16.15) (13.20) (10.13)

CoSBj2H2O Greenish-brown 19.42 15.68 11.81(1952) (15.80) (11.92)

CoSB22H2O Redish-brown 18.78 15.32 1l.31(18.65) (15.13) (11.39)

CoSB32H2O Brown 16.29 13.08 10.22(16.18) (13.19) (10.08)

"Values in parentheses are those calculated for 2 water molecules---------------

825

INDIAN J. CHEM., VOL. 21A, AUGUST 1982

620°C leaving metal oxide as the residue. The order ofthermal stabilities is: Ni > Co > Cu.

A sharp IR band at 3470-3455 exhibited by theligands is assigned to vOH and a medium intensityband at 2815-2805 to intramolecular hydrogen bondedvOH6

. These vOH bands are absent in complexessuggesting that both the phenolic OH groups aredeprotonated on complex formation. However, theappearance of a band at 3585-3575 in the complexescould be due to vOH of associated water moleculewhich is further confirmed by the presence of a band at1615-1605 due to c50H of water molecule", Themedium intensity band at 740-725 could be due torocking mode of coordinated water molecule 7

• Thebands at 1745-1730, 1535-1525 and 1280-1270 in theligands are assigned to amide-I (mainly due to vC = 0),amide-Il (due to vC - N + c5NH)Mand amide-III (due tovC-N+c5NH2)9 respectively. In the complexesamide-I band shifts by 1O-20cm -I to lower frequencyregion (1735-1715) while amide- II and amide- III bandsshift by 5-25 cm -I to higher frequency regions, 1560-1545 and 1290-1285 respectively. These changes inamide group vibrations suggest that the carbonyloxygen is coordinated to metal ion Io. The vC = N bandoccurring at 1585-1580 in the Iigands II shifts by 10-15em -I to lower frequency region (1570-1565) in thecomplexes suggesting that the nitrogen of azomethinegroup is bonded to metal ion. The low intensity bandsappearing at 530-510 and 480-465 in the complexes areattributed to vM - 0 and vM- N modesrespectively 1.12.

The IR spectral evidence indicated deprotonation ofboth the phenolic OH groups. Since these are at parapositions, both cannot coordinate to the same metalion due to steric hindrance. Hence structure(I) isproposed for the complexes in which coordinationpolymerization grows involving metal ion as abridging unit between donor sites of different ligandmolecules.

n

Cu(II) complexes gave J1eff values in the range 1.80-1.92 B.M. indicating the presence of one unpairedelectron. The absorption spectra of these complexesexhibit a broad band at 16130-15630 em -I assignableto 2 E --+ 2 T2 transition on the basis of which a

Ii g

826

distorted octahedral geometry is suggested for thecomplexes+'. The broadening of the band may be dueto Jahn-Teller effect!".

The J1eff values for Ni(II) complexes are in the range2.88-2.97 B.M. suggesting an octahedral configurationwith 3A 2g ground term 15. The absorption spectraexhibit three bands at 24390-23810, 15600-153.80 and11360-11230cm-1 which are attributed to 3A2g

3 3 3 d " 3 ..--+ TIg(P), A2g--+ TIg(F) an A2g--+ T2g transitionsrespectively I 6.1 7.

The magnetic moments of Co(II) complexes are inthe range 4.88-4.96 B.M. suggesting a high-spinoctahedral geometry with very high orbital contri-bution attributable to the three-fold degeneracy of the4 T11(F) ground term 15. The absorption spectra of thesecomplexes exhibit two bands at 21280-20410 and12050-11760 cm -I which are assigned to 4 T1g(F)--+ 4 T, (P) and 4 T, (F) --+ 4A 0 (F) transitions re-

I( g ~spectively in octahedral geometry!". However, due tolimited spectral range of the instrument the transition4 T1/F) --+ 4T2g(F) could not be observed.

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