INDIAN J. CHEM., VOL. 15A, SEPTEMBER 1977

ComplexTABLE 1 - MELTINGPOINT AND ANALYTICALDATA OF CADMJUM(II)HALIDE ADDUCTS

Found (Calc.), % m.p.(OC)

CdCl •.PDPSCdCl2·PDPSeCdBr z-PDPSCdBr a-EDPSeCdBr •.PDPSeCd.Br4·BDPSeCdBr2·HDPSeCdl s-EDPSCdl2·BDPSCdl s-PDPSCdI2·EDPSeCdI2·PDPSeCdl s-BDPSe

C49'09 (49'15)43·28 (43-03)43·86 (43'18)37·78 (37'70)38·85 (38'48)30'77 (29'79)41·86 (40'70)37·59 (37'70)40·72 (39'25)39·15 (38'48)34'52 (33'80)36·15 (34-61)36·24 (35'37)

H4-14 (3,94)3-69 (3045)3·82 (3047)2'95 (3,00)3·21 (3,09)2-66 (2'48)3-69 (3-60)2·87 (3'00)3·51 (3'27)3·15 (3'09)2-67 (2-60)3'50 (2'78)3'18 (2'95)

PIS10'6(S) (9'71)7'20(P) (8'52)8'2(S) (8'55)7'8(P) (7'7)

7'20(P) (7'36)5'5(P) (5'5)6'3(P) (7'0)7'7(P) (7'7)6'7(S) (7048)

6'5(P) (6'70)5'6(P) (6'62)6'5(P) (653)

22S(d)240228-30232(d)250(d)275(d)

75(d)250-52240(d)242-44260(d)275(d)265 (d)

cated Instrumentation Centre, IIT, Madras, for re-cording far infrared spectra in the range 650-200 cnr+.References

1. BANNISTER,E. & COTTON,F. A·,I chem.Soc. (1960),1959.2. NICPON, P. & MEEK, D. W., Chem. Commun. (1966),398.3. VEER, W. & JELLINEK, F., Reel. Trau. chim: Pays-Bas.

Be/g., 85 (1966), 842.4. DALZIEL,J. A. \V., HOLDING, A. F. LE C. & WATTS, B. E.,

I chem. Soc. (A) (1967), 358.5. MALHOTRA,K. c., Indian I cu«; 12 (1974), 823.6. NEGOJU,M. & SPACU,P., Chem. A bstr. , 75 (1971), 117880b.7. MEEK,D.W. &NICPON,P.,I Am. chem, Soc., 87 (1965),4951.8. KING, l\1. G. & MCQUILLAN, G. P., I chem. Soc. A

(1967), 898.9. SLINKARD,W.E. &MEEK,D.W.,Inorg. Chem.,8 (1969),1811.

10. SLINKARD,W. E. & MEEK, D. W., I chem. Soc., DaltowTrans. (1973), 1024.

11. WHEATLAND,D. A., CLAPP, C. H. & WALDRON, R. \\T.,Inorg. Chem., 10 (1972), 2340.

12. KING, M. G., MCQUILLAN,G. p. & MILNE, R., I inorg.nucl, Chem., 35 (1973). 3039.

13. NICPON, P. & MEEK, D. W., Lnorg. Synth., 10 (1967), 157.14. SANDHU, S. S. & SINGH, T., Transition Met. cu-«, 1

(1976), 155.15. TIETHOF, J. A., HETEY, A. T. & MEEK, D. W., Inorg,

Chem., 13 (1974), 2505.16. ADAMS,D. M., Metal-ligand &- related vibrations (Edward

Arnold, London), 1967, 26, 316.17. FERRARO, J. R., Low-frequency tnbrations of coordination

compounds (Plenum Press, New York), 1971, 111, 247.18. COATES,G. E. & RIDLEY, D., I chem. Soc. (1964). 166.19. CLARK, R. J. H. & WILLIAMS, c. S., lnorg. cu«, 4

(1965), 350.20. CLARK,R. J. H. & DUNN, T. M·,I chem. Soc. (1963), 1198.

Complexes of 2-Antino-5-phenyl-l,3,4-thiadia-zole with Cu(II), Ni(II), Co(II), Fe(lI) & Zn(lI)

Sulphates

N. B. SINGH & l SINGHChemistry Department, Gorakhpur University, Corakhpur

Received 10 January 1977; accepted 16 April 1977

Complexes of Cu(I1), Ni(II), Co(II), Fe(II) and Zn(II)sulphates with 2-amino-5-phenyl-l,3,4-thiadiazole havebeen prepared and characterized on the basis of ana-lytical, magnetic susceptibility, infrared and electronicspectral, TGA, DTA and DTG data. The ligand showsbidentate behaviour in all the complexes except in thecase of Ni(lI) complex where it acts as a monodentateligand. All the complexes reported have octa-hedral stereochemistry except [Cu(2-amino-5-phenyl-1,3,4-thiadiazole)2]SO, which is square-planar.

832

THE ligand, 2-amino-5-phenyl-l,3,4-thiadiazole (I)has four potential donor sites, viz. three nitrogen

atoms and one sulphur atom. It will therefore be?f interest to investigate the nature of bondingIII the complexes formed by 2-amino-5-phenvl-1,3,4-thiadiazole. In this note, we report t-heresults of our studies on the Cu(II), Ni(II), Co(II).F e(II) and Zn(II) sulphate complexes.

N---NII II

Ph-C C-NH.

"'s/(I)

All the chemicals used for the preparation ofthe complexes were of AR or chemically puregrade. The ligand, 2-amino-5-phenyl-1,3,4-thiadia-zole (hereafter denoted as APTH) was preparedbv the literature methods.

- Th~ complexes were prepared by mixing aqueoussolutions of metal sulphate hydrates with the etha-nolic ~olution of liga~d in (1: 1) ratio and refiuxingthe mixture for 30 rmn, 1 hr , 2-3 hr in the case ofCu(I!); Ni(II), Co(II) and Fe(II) , Zn(II) com-plexes respectively. The complexes obtained werefiltered and washed with hot ethanol and waterand dried in vacuo.

Elemental analyses and magnetic measurementswere carried out using standard methods. Electronicand IR spectra, TGA, DTA and DTG of complexeswere also recorded using standard methods.

Th~ mol~cular formulae and the elemental analysesare grven III Table 1. On comparing the infraredspectra of the ligand with those of the complexes,It was found that the positions of most of the bandshad shifted. The asymmetric and svmmetric 'INHob.served at., 3350 and 3270 crrr" in the ligand .wereshifted to 3.)60-3430 and 3280-3330 crrr+ respectIvelyin the spectra of the complexes. 'IC-S observedat 648 cm-l in th.e ligand was shifted to a positionbelow 60~ crrr" I~ t~e spectra of the complexes.!hese . evidences indicate that the complexationIS taking place through the sulphur atom andnitrogen atom of the NH2 group.

From the analytical data and molecular formulaeof the complexes, it is apparent that, in the case ofNi(II), the APTH behaves as a monodentate

NOTES

TABLE 1 - AXALYTICALAND MAGNETICMOMENT DATA OF METAL(ll) SULPHATE COMPLEXESWITH 2-AM1NO-5-PHENYL-1,3 4-THIADIAZOLE(APTH)

Complex Colour Found (calc.). 0/ Ileff10

M C H N S(B.M.)

[Cu(APTH)21S0• Black 12·10 36'64 2'74 16·20 18·50 2·04

[Ni(APTH)&lS04 Grey-(12'36) (37'39) (2'72) (16'35) (18.69)

4'40 47·02 3·76 20·66 18·10 3·24

[Co(APTH)3]S04green (4-82) (47'32) (3-45) (20'07) (18'41)

Dark violet 8·90 41·82 3·16 18·22 18·90 4·84

[Fe(APTH)3]SO. Yellow(8'58) (41'98) (3-06) (18'36) (18'65)7·80 41·74 3·23 18'64 18-40 5'62

[Zn(APTH)3'S04 White(8'17) (42-18) (307) (18-45) (18'74)9·50 41'06 3·06 17'92 18·00 diarnag-

(9'43) (41'60) (3,03) (18'20) (18'48) netic

ligand, whereas in other complexes, APTH behavesas a bidentate ligand.

Electronic spectrum of the Cu(II) complex showsa unique strong ~eak near 525 nrn (19048 crrr+,or 19·048 kK) assignable to a d-d transition in asquare-planar field2.

The observed magnetic moment value of Cu(II)complex is 2·04 B.M. which shows the presence ofone unpaired electron normally expected for Cu(II)complexes.

The electronic spectrum of Ni(II) complex showsthree weak hands at 1075 (9302 cm'"], 635 (15748crrr '] and 385 nm (25974 em-I) characteristic ofoct~hedral Ni(II) ~~n. These bands may beassigned to the transrtions ; 3Au-+3T2g(vl)' 3A2p3TJg

(F) (v2) .and 3A2g-+3Tg (P) (V3) respectively.The ratio V2/Vl ~ 1·69 is usually acceptedfor octahedral Ni(II) complexes''. The values ofDq, B', ~o and ~ calculated! using the values ofthese transitions are 930·2 crrr+, 921 cmt, 12·78and 0·87 respectively.

The magnetic moment value of Ni(II) complexis 3·24 B.M. which shows the presence of two un-paired electro~s and is typical o~ octahedral Ni(II)complex. ThIS fact accompanied by magneticmoment and electronic spectral results led us tobelieve tha~ ?ctahedral stereochemistry is most likely.

The position, shape .and very low intensity ofthe absorption bands In the electronic spectrumof Co (II) complex are approximately similar tothose previously reported for octahedral Co(II)complexes+", The spectrum consists of bands at1125 nm (8888 cm+) and 500 nm (20000 cm+). Thefirst band may be identified with the transition4T}g(F)-+4T2g and the second band may be dueto the transition 4Tg(F)-+4TIg(P). The Dq, B',~o and ~ values are 1004·6 crrr", 818 crrr", 15·40and 0·84 respectively. These values have beencalculated using the frequencies corresponding toVI and Va transitions-. Using the relationshipV2= v1+l0 Dq, the V2 band would be expectedto occur at 18934 cnr+.

The magnetic moment of the Co(II) complexwas found to be 4·84 B.M. which is characteristicof high-spin octahedral Co(II) complexes".

The electronic spectrum of Fe(II) complex showsa broad and weak band around 1000 nm, whichis due to the transition 5T2p5Eg and is charac-teristic of high-spin octahedral iron (II)9.

TABLE 2 - TGA DATA FOR THE COMPLEXES OF 2-AMINO-5-PHENYL-l,3,4-THIADIAZOLE

Stable phase Temp. Total wt loss (%)range --------

(0C) Found Calc.

[Cu(APTHlz]SO.

[Cu (APTH)]SO. 120-340 35·8 34-46CuSO. 360-475 69·89 68·931/2 C1120 475-620 86·00 86·07

[Ni(APTH)6]S04

[Ni(APTH).]SO. 120-360 30·11 29·08[Ni(APTH)]SO .• 360-~80 73·4 72·72NiSO. 400-620 87'5 87·27

[C(J(APTH)3]SO.

[Co(APTH)]SO. 100-600 52·91 51·6CoSO, 600-620 77·93 77-4CoO 660-720 89·31 89·07

[Fe(APTH),)SO.

[Fe(AFTH)2S0]4 120-320 27·68 25·9[Fe(APTH)JSO, 320-560 53·14 51·8FeSO. 600-660 77·46 77·71/2Fe,03 680-780 88·70 88·2

[Zn(APTH),]SO,

[Zn(APTH)JSO. 80-580 52·3 51·1ZnSO. 620-660 77·23 76·7ZnO 700-780 88·53 88·2

The observed magnetic moment value 5·62 B.M.is consistent with the octahedral stereochemistryfor iron(II)lO,l1.

Zn(II) having the configuration 3d10, is expectedto form diamagnetic complex and on the basis ofelemental analysis and IR spectra of the complex,an octahedral structure for the complex may beproposed.

On the basis of thermoanalytical data, the probablemechanisms of decomposition of the complexesare given in Table 2. The decomposition productsof the Cu(II) complex have been analysed. .F;le-mental analysis shows that the decompositionproduct at 3400 is a stable 1: 1 phase [Cu(APTH)]S04 [Found: Cu, 18·50; C, 28·27; H, 2·42; N, 12·36;S, 18·85. Cu(APTH)S04 requires Cu, 18·87; C,28·48; H, 2·07; N, 12·46; S, 19·0%].

833

INDIAN J. CHEM., VOL. 15A, SEPTEMBER 1977

The decomposition product at 475°, i.e. afterthe complete removal of the ligand was found tobe . CU~04' This was confirmed by quantitativeestimation of copper and sulphate ions. This wasfurther confirmed by taking the powder Xvraydiffraction pattern. The observed d values werein good agreement with the literature values's.

The authors are grateful to Prof. R. P. Rastogi,Head, Chemistry Department, Gorakhpur University,for his keen interest and kind encouragement. Theauthors are thankful to Dr P. P. Singh of M.L.K.College, Balrampur, for providing necessary faci-lities for magnetic measurements and also to ShriV. N. Mulay and Shri R. C. P. Bipin, ChemistryDepartment, BHU, Varanasi, for elemental analysisand recording the spectra.

References1. MAFFII, G., TESTA, E. & ETTORRE, R., Chern. Absir.,

53 (1959), 2211.2. TOMLINSON, A. A. G., HATHWAY, B. J., BILLING, D. E. &

NICHOLS, P., J. chem, Soc., A (1969), 65.3. SACCONI, L., Trans. metal Chem., 4 (1968), 199.4. LEVER, A. B. P., J. chem, Educ., 45 (1968), 711.5. ELBECK, \V. J., HOLMES, F., TAYLOR, C. E. & UNDERHILL,

A. E., J. chem. Soc., A (1968), 1189.6. CARLIN, R. L., Trans. metal cu-«, 1 (1968), 3.7. DEVOTO, G., PONTICELLI, G. & PRETT, C., J. inorg. nucl.

Chem., 37 (1975), 1638.8. EILBECK, W. J., HOLMES, F. & UNDERHILL, A. E., J. chem,

Soc., A (1967), 757.9. COTTON, F. A. & WILKINSON, G., Advanced inorganic

chemistry, a compressive text, 3rd edn (Interscience,New York), 1972.

10. FrGGIS, B. N. & LEWIS, J., Progr. inorg. Chem., 6 (1964), 37.11. FREGNI, C., PRET!, C., TOSI, G. & VERANI, G., J. inorg.

nucl. Chem., 37 (1975), 1838.12. Cumulative alphabetical and grouped nit merical index of

X-ray diffraction data (ASTM Card IfIl 1-1081),1953.

Pd(II) Complexes with Some New Monoazo Dyes

R. B. KHARAT

Department of Chemistry, Nag pur Uuiversity, Na-rpur

Received 17 September 1976; accepted 21 May 1977

2-Carboxy-2'-hydroxy-5'-methylazobenzene - 4 - sul-phonic acid, 2-carboxy-5'-chloro-2'-hydroxyazoben-zene-4-sulphonic acid and 2-carboxy-2'-hydroxyazo-benzene-5'-4-disulphonic acid are proposed as newreagents for the spectrophotometric determination ofPd(U) in the concentration range 0·2-11·3, 0·3-10·6 and0·1-10·6 ppm respectively. The acid dissociationconstants of the Ilgands, the composition and stabilityconstants of Pd(II) chelates(I: I) have been evaluated.The influence of some common ions is reported.

SOME new monoazo dyes, viz. 2-carboxy-2'-hydroxy-5' -methylazobenzene-4-sulphonic acid

(CHMAS), 2-carboxy-5' -chloro-S' -h ydroxyazobenzene-4-sulphonic (CHCAS) and 2-carboxy-2'-hydroxyazo-benzene-5',4-disulphonic acid (CHADS) have beensynthesised and used for the spectrophotometricdetermination of Pd(II). The complexes of Cu(II),Ni(II) and Pd(II) with some reagents belongingto this class have been investigated previously>",

2-Carboxy-2' -hydroxy-5' -methylazobenzene-s-sul-phonic acid (CHMAS) was prepared as previously

834

described". 2-Carboxy-5' -chloro-S' -hydroxyazoben-zene=l-sulphonic acid (CHCAS) was synthesizedfrom 5-sulphoanthranilic acid4 which was diazotizedand immediately coupled with p-chlorophenol inalkaline medium. The product was isolated asits barium salt and converted into sodium salt bytreating it with a calculated amount o.f sodiumsulphate. The sodium salt was recrystallized fromaq: ethanol. Finally the dye was purifi.ed by makingits free acid. The free acid was crystallized repeated-ly from 50% ethanol. The purity was checked byTLC (Found: C, 43·6; H, 2·4; N, 8·0; S, 8·8; Cl,10·0; eq. wt 178·1. C13H9N2ClS06 requires C,43·8; H, 2·5; N, 7·9; S, 9·0; CI, 9'9%; eq. wt 178·4).

2-Carboxy-2' -hydroxyazohenzenc- 5' ,4-dislllphonicacid (CHADS) was synthesized as described forCHCAS bv coupling" with p-sulphophenol. Thedye was purified as in tbe case of CHCAS and i~spurity checked by TLC (Found: C, 38·5; E, ~'J;N, 7·31; S, 15·7; eq. wt 133·7. C13HlON2S209requtresC, 38·8; H, 2·5; N, 7·0; S, 15·9%; eq. wt 134·1).

Stock solutions of these dyes were prepared bydissolving them in aqueous solution of requiredamount of sodium hydroxide. Pd(II) rerchlnratesolution was prepared from palladium chloride(AR) and was standardized by dimethylglyoximemethod. All other reagents were of AR grade.

A Beckman DU-2 spectrophotometer along withsilica cuvets of 1 em optical path was used formeasuring the absorbances. Beckman H-2 pHmeter with glass calomel electrode system wasused for pH measurements.

All experiments were performed at room tempe-rature. The pH of the solution was adjusted withsodium hydroxide and perchloric acid solutions ..

The variation of Amax with pH has been studied.The results indicated that all three reagents havetwo Amax at higher pH which can be attributedto the dissociation of phenolic group. It has alsobeen observed that the Amax and molar absorpti-vities of the reagents change with the nature ofsubstituent group present at p-position with respectto nhenolic OH.

The acid dissociation of the ligands may be re-presented as:H3CHMAS ~H2C HMASl-~HCHMAS2-~CHMAS3-

k, k, k.... (1)

H3CHCAS~H2CHCASl-~HCHCAS2-~CHCA,S3-h, k, h,

... (2)H4CHADS~H3CHADSl-~H2CHADS2-~

k, k, k,

HCHADS3-~CHADS4- .: (3)k,

The -SOaR group present might be dissociatingat lower pH value and thus not permitting itsdetermination (PK1 of CHMAS and CHCAS andpKl and PK2 of CHADS) under the present condi-tions of study.

The spectrophotometric method? gave the valuesof pK2 and PK3 to be 3·50 and 10·30 for CHMAS,and 3·45 and 8·90 for CHCAS respectively. Thevalues of PK3 and pK4 obtained for CHADS were3·45 and 8·50 respectively. The PK3 of CHMASand CHCAS, and PK4 of CHADS were further