Mukerji, S. K.

Sogan, N. C.

English

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INDIAN J. CHE:\1., VOL. 15A, APRIL 1977TABLE 1 - ANALYTICAL AND CONDUCTANCE DATA FOR THE LIGAND AND ITs COMPLEXESCompound Molar Calc. (%) Found (%)conductancein EtOH M C H M C H(ohrn-! em'mole-I)C13HllNOS* 68·12 4·80 67·82 4·69H[Pd(C'3HIONOS)Cl,Jt 82t 26·17 38·38 2·70 26·00 37'96 2·62[Pd(C'3HIONOS),J 0·0 1891 55·47 3·55 18·60 55·32 3·27[Hg(C'3H'ONOSz] 0·0 30'55 47·51 3·04 30·23 47·21 2·92[Hg(C13HIONOS}] 0·0 46·80 36'39 2·33 46·39 36·08 2·30[Ag(C,.H,oNOS) J 0·0 32·11 46·44 2·97 32·00 46·06 2'88*[S: Calc. 13-97. Found: 14-06%]. HCl: Calc. : 17'22. Found: 17'10%]. tIn nitromethane.respectively as revealed by ampcromctric titratior s.The titrations were carried out at the plateau ofthe polarogram of Pu(II) chloride (-0·44 V). Inthe case of 1:1 Hg(I) ar d Ag(I) complexes ard 1:2Hg(I1) complex the ti tratior.s were carried out atthe plateau of the polarogram of the ligar.d (- 0·55V). These stoichiometries were cor-firmed by co 1-ductometric ti tratio: SProcedure for the determination - 50 ml of 1111KCI or KNOa were added to a known volume ofstandard metal io.. solutioi a:.d tile volume madeup to 100 ml by adding doubly dstillod water. Analiquot (20 ml) of this solution was trar.sforred toa polarographic cell aid deaerated by bubblii.g purenitrogen gas. A potu-itial of -0·44 V in tIle deter-miuation of P(l(II) a-id -0,55 V in the determir.a-tion of other metals (vs SeE) was applied, usingdme as au indicator electrode. Measured volumesof the reagent solution were added ai.d after eac haddition, the solution was stirred by bubbliignitrogen gas and the current was measured afteran interval of a few secor.ds.12-/21'3 ppm of Pd(II). 60-/100 ppm of Hg(II),120-/200 ppm of Hg(I) and 50-fl08 ppm of Af:,(l) canbe d.etermir ed with an accuracy of ± 0'5%.Interference by the prosevce of exterr al cons wasstudied by taki+g a-i aliquot of the metal '01'. solu-tion, addrig 5-10-fold eXCeSSof the foreign ion ar.dcarryi 19 out the ti tratior s as described aboveLi(I), Na(I}, K(l), Rb(I). Tl(l). Mg(II). Ca(II).Sr(II). Ba(II). Fe(II). Co(II}. N.(II). Cu(I1). Zn(II).Pb(II), Cd(II). Mn(II}. Sn(II}, U02(1I). AI(III),Cr(III). Fe(III), TI(III), As(III), Sb(III), Bi(IIIl,In(III), Ga(IJI), La(III), Ir(III), All(III), ~·n(lV).Th(IV), Zr(IV). Ce(IV), Pt(IV), Mo(VI), W(VI)do not interfere while even the traces of Ru(III)and Rh(III) interfere.However, Pd,(II) , Hg(I and II) a~cl Ag(I} interferein each other's estimation.Preparation of the solid complexes and their IRstudies - 1:2 (metal-Iigar d) complexes of Hg(II)and Pd(II) and 1:1 complexes of Hg(I), AdI) ai clPd(II) were prepared by mxr.g the calculatedamounts of reactants contair.ir g a little excess ofthe latter. The nrecipi tates \\ ere filtered, w ashedseveral times with distilled water ar d tl.en driedin vacuo over anhydrous H2S04, The separationand washings of the suspended precipitates of 1 :19Pd(I1) complex were carried out by centrifuging.366The silver complex was not photosensitive. Theanalytical and conductance data of the complexesare gi ven in Table 1. All the complexes, exceptthe 1:1 Pd(I1) complex, are non-electrolytes indhanol.The vOH band observed at 3240 crrr? in the IRspectrum of the ligand disappeared in the spectraof the palladium complexes while a very weak bandat 2590 em? in the spectrum of the ligand due to'.ISH disappeared in the spectra Hg{II), Hg(l) andAg(I) complexes. There was a shift in the pos itionof v-C=N- band from 1580 cm-1 in the ligandto ] 560 crrr? in the spectra of Pd(I1) and Hg(II)complexes. This indicates the coordination ofPcl(II) through oxygen and nitrogen and of Hg(II)through sulphur and ni trogen.References1. MALIK, W. U. & SHARMA, c. L., J. Indian chem. Soc., 45(1968), 503.2. FREEMAN, D. C. & WHITE, C. E., J. Am. chem, Soc .• 78(1956), 2678.3. l\1ELOAN, C. E. & KISER, R. "V., Problems and experimentsin instrumental analysis (C. E. Merrit Books Inc.,Columbus, Ohio), 1963, 127.N-Phenyl-N -(2- benzothiazolylazo )hydroxyl-amine as an Analytical Reagent for Pd(I1),Cu(I1) & Ni(lI)S. K. MUKERJ! & N. C. SOGAN!Chemistry Department, University of Rajasthan, JaipurReceived 25 October 1976; accepted 21 December 1976N-Phenyl-N-(2-benzothiazolylazo )hydroxylamine hasbeen successfully used as an analytical reagent forthe gravimetric determination of Pd(II), Cu(II), andNi(II). The solid complexes of the general formula,(CI3H.N,SO),M, have been isolated at pH 2·5-3·0 forPd(II) and Cu(II) and at pH 4·5-5·5 for Ni(II). Thestability constants of chelates have also been deter-mined pH-metrically in aq. dioxane.MUKERJI in a comparative study of the efficacyof various hydroxamic acids for the determina-tion of metal ions, established the superiority ofthe title reagent! over N-phenyl-N-(phenylazo)-hydroxylamine and its analogues--". The analyticalutility of the reagent for Cu(tI) is described inthis note. However, Pd(II) and Ni(II) were alsodetermined by a similar procedure. The pka valueof the reagent was determined spectrophotometr i-cally- and was found to be 11·36±0·02 at 414 nmand 25°. The precipitated metal chelates havethe formula (C13H9N4SOhM, where M=Pd(II),Cu(II) or Ni(II). The stability constants of thechelates of Cu(II), Pd(II) and Ni(II) have also beendetermined pH-met! ically" at 25° ± 0·5° and (J.=O·lM(NaCI04) in aq. dioxane.The reagent has intramolecular hydrcgen-bondedtrans-structure as revealed by electronic and IRstudies", Other compounds having the same func-tional group ai e also assigned a similar structurebased on NMR7 and IR data after 15N labelling",The solutions of metal ions, carbonate-free sodiumhydroxide and buffer solutions were prepared bydissolving weighed amounts of AR grade salts,and standardized by conventional methods wherevernecessary. Dioxane was purified by the conventionalprocedure. pH was measured on a CambridgeBench type pH-meter.Estimation of Cu(II) - A solution of CuS04.5H20containing 20 mg of the metal was diluted to about150 ml, and 4 ml of 10% (w/v) sodium potassiumtartrate added to it to stabilize the complex fcllowedby 2'5 ml of IN HCI to bring the PH between 2·5and 3. To this solution which might also containvarying quantities of foreign ions, a 1% (w/v)ethanolic solution cf the reagent was added inexcess (25%). The copper complex separated outas a light-violet precipitate. It was digested, filter-ed, washed and dried to a constant weight at 120°to 125°.Several determinations were made using varyingamounts of the reagent under different pH condi-tions. Completion of the precipitatic n was testedboth gravimetrically and by spot tests on the filtrate.The removal of excess of reagent by complete hydro-lysis was indicated by the formation of a bluish-black colour on adding a drop of NaOH solution,whereas incomplete hydrolysis was indicated by agreenish-yellow colour.It has been found that 10-30 mg of Cu(II) canbe determined accurately using this reagent in thepresence of eight-fold excess of Cd(II), Hg(II) andAI(III) five-fold excess of Co (II), Ni(II) and Zn(II),four-fold excess of Ti(IV), Fe(II) , Fe(III), Sn(II),Bi(III) and Sb(III), and three-fold excess of Ce(IV),Mn(II) and Zr(II).Pd(II) forms a chocolate co loured complex be-tween pH 2·5 and 3·0 whereas Ni(II) forms a deepTABLE 1 - STABILITY CONSTANTS (AT [.I.= O·IM) ANDCONVERSION FACTOR OF METAL COMPLEXESMetalConversion log K1K. Conversion log ](lK.factor factorPd(II)Cu(II)Ni(lI)0'20090·13030·121522'6622·3117·500·16510·10550·098422·9222·6317·88NOTESyellow granular complex between pH 4·5 and 5'5.Alkali and alkaline earth metals, Pb(II), Rh(II),Ir(III), Pt(IV), Tl(IV) and La (III) did not yielda more deeply coloured precipitate with the reagent.The metal chelates formed by the reagent aremore intensely colour ed, thermally stable, havemore favourable conversion factors and greaterstability constants (Table 1) than those of N-phenyl-N-(phenylazo)hydroxylamine. The presenceof a heterccyc1ic benzothiazole ring may be attri-buted to the intensification of colours of the chelatesand to a better ccordinating tendency. In repro-ducibility of the results and specificity this reagentis superior to all other reagents used for determiningCu(II) and Pd(II).The authors are grateful to Prof. J. N. Gaur forproviding necessary facilities.References1. MUKERJI, S. K., Studies of metal chelates of hydroxylamineanalogues, Ph.D. thesis, University of Rajasthan,J aipur, 1970.2. SOGANI, N. C. & BHATTACHARYA, S. C., J. Indian chem .Soc., 36 (1959), 563.3. PUROHIT, D. N. & SOGANI, N. c., Bull. chem, Soc. Japan,37 (1964), 476.4. ROBINSON, R. A., Abstract of symposium on structure ofelectrolytic solutions, Washington, 1957, 90.5. CALVIN, M. & MELCHIOR, N. C., J. Am. chem. Soc., 70(1948), 3270.6. MUKER]I, S. K. & SOGANI, N. c., Bull. Acad. Polon. su.,Ser. Sci. Chim., 23 (1975), 463.7. CHAKRAVORTY, A., BEHERA, B. & ZACHARIAS, P. S.,Inorg. chim. Acta, 85 (1968), 2.8. MITSUSHASHI, T., OSAMURA, Y. & SIMAMURA, D., Tetra-hedron Lett., (1965), 2593.Solvent Extraction & SpectrophotometricDetermination of Ru(III), Rh(III) & Pd(lI)using 1-(2' -Pyridylazo)-2-phenanthrolB. S. GARG & R. P. SINGHDepartment of Chemistry, University of DelhiDelhi 110007andA. K. RrsHIDepartment of Chemistry, A.R.S.D. CollegeNew Delhi 110021Received 14 November 1975; accepted 23 September 19761-(2'-Pyridylazo)-2-phenanthrol (PAP) forms chloro-form soluble coloured complexes with Ru(III), Rh(III)and Pd(II) with J.,max 615; 580, 625; and 610, 665 nmrespectively. The extinctions of the complexes remainmaximum and constant in the pH range 4·7-6·1;4·0-8·0; 3·0-7·0 for Ru(III)-PAP; Rh(III)-PAP andPd(II)-PAP complexes respectively. The sensitivitiesof the colour reactions are 0·0049 at 615 nm; 0·0044at 580 nm, 0·0048 at 625 nm; 0·016 at 610 nm, 0·013 at665 nm respectively. A modification of the methodenhances the selectivity for the determination ofRu(III).THE use of l-(Z'-pyridylazo)-Z:phenanthrol (PAP)as a good chromogenic reagent for transitionmetal ionsv? has been earlier determined by us.367

N-Phenyl-N -(2- benzothiazolylazo)hydroxylamine as an Analytical Reagent for Pd(II), Cu(II) & Ni(II)

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N-Phenyl-N -(2- benzothiazolylazo)hydroxylamine as an Analytical Reagent for Pd(II), Cu(II) & Ni(II)

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