Pradhan, B.

Rao, D. V. Ramana

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for Nesalicylidene-e-amino acid complexes ofcobalt(II) appears to be applicable in the case ofthe present complexes involving schiff bases derivedfrom (l-, ~- and y-amino acids. The experimentaldata are also in agreement with a dimeric structure.References1. BARLELEW, C. H. & CALVIN, M., J. Am. ehem, sse., 68(1946), 2251.2. BRUCKNER, S., CALLIGARRIS, M., NARDIN, G. &RANDACCIO,L., Acta Crystallogr. (Sect. B), 25 (1969), 1611.3. SCHAEFER, W. P. & MARSH, R. E, Acta Crystal/ogr. (SectB), 25 (1969), 1615.4 JONES, R. D., SUMMERVILLE, D. A. & BASOLO, F., Chem.Revs., 79 (979), 139.5. CARLISLE, G. O. & THERIOT, L. J., J. inorg . nucl. Chem.,35 (1913),2093.Mixed Chelate Complexes of Manganese(III)B. PRADHAN & D. V. RAMANA RAo*Department of Chemistry, Regional Engineering College,Rourkela 769008Received 14 August 1980; revised and accepted 16 December 1980Five mixed chelate complexes of manganese(III}, viz. Mn(tsc).(acac), Mn(tsc).(pyca), Mn(tsc).{et.dtc), Mn(acac).(pyca)and Mn(acac)(pyca)., where tscH = thiosemicarbazide, acacH =acetylacetone, pycaH = picolinic acid, et.dtc = diethyldithio-carbamate, have been isolated. The thiosemicarbazido complexeshave been obtained on oxidation of manganese(ll) by air in alkalinemedium whereas the other two mixed chelates have been obtainedfrom manganese(IlI) compounds by substitution reactions. Thecompounds have been characterized on the basis oftheir elementalanalyses, molecular "Weight, molar conductance, magnetic sus-ceptibility, infrared and electronic spectral data.THE 3+ oxidation state of manganese has beenwell-characterized by the preparation of a num-ber of anionic, cationic and neutral complexes and agood number of mixed chelate and mixed ligandcomplexes':". The complexes were generally ob-tained starting from the manganese(III) compounds.in the present investigation besides the usual methodfor isolating Mn(III) complexes, a method involvingNOTESoxidation of divalent to trivalent manganese in thepresence of ligands has been used.(i) Preparation of Mn(tsc).iacac), Mn(tsch(pyca)and Mn(tscMet~dtc) -Ethanolic solutions of manga-nese(II) chloride, acetylacetone/picolinic acid/sodiumsalt of diethyldithiocarbamic acid and thiosemicar-bazide in 1 : 1 : 2 molar ratio were reacted. Ethano-lie sodium hydroxide solution was added to it tillfaintly alkaline and then air was bubbled through theresulting solution for one hour when the colourlesssolution darkened and the compounds separated out.These were filtered, washed with ethanol, ether anddried in vacuo.(ii) Preparation of Mn(acacMpyca) - Tris (acetyl-acetonato)manganese(III), Mn(acac)a, in chloro-form and picolinic acid in ethanol were refluxed in1 : 1 molar ratio for one hour. The volume wasreduced to one-third by suction and the contents keptovernight when the compound separated out. It wasfiltered, washed with ethanol, ether and dried invacuo.(iii) Preparation of Mn(acac)(pyca)2 - Tris (acetyl-acetonato)manganese(III), Mn/acacj., in chloro-form and picolinic acid in ethanol were mixed in 1 : 2molar ratio and refluxed for 15 min when the com-pound separated out. It was filtered, washed withethanol, ether and dried in vacuo.Elemental analyses (Table 1) carried out by stan-dard methods were consistent with the formulationsof the compounds. The molar conductances for,..., 10-3M solutions of the complexes in nitro benzene mediumrange between 2.1 and 2.9 m ho em" mole=' indicatingthe non-electrolytic nature of the compounds.The magnetic moment values (determined usingGouy method) of 4.92-5.08 B.M. (Table 1 ) indicatethe presence of four unpaired electrons correspondingto high-spin manganese(III) state with 5Eg groundterm. The molecular weight measurements (Rastmethod using camphor) indicate that the compoundsare monomeric.Thiosemicarbazide exists in the tautomeric forms(I)and (Il) and can act as a neutral or charged chelatinggroup'.Haines and Sun" have reported that in thiosemi-carbazido complex, the band at 1049 cm? for freethiosemicarbazide becomes very weak and a newstrong band appears at 9W crrr", Such features canTABLE 1 - ANALYSES, COLOUR, MELTING POINTS, MAGNETIC SUSCEPTIBILITY AND MOLECULAR WElOHTs DATA OF MIXED CHELATEMANGANESE(III) CoMPLEXESm.p. Found (Calc.) % !Lerr Mol. wtCompound Colour (0C) (B.M.) foundMn S (calc.)Mn(tsc).(acac) Chocolate >300 16.04 18.70 5.05 356.2(16.44) (19.19) (335.9)Mn(tsch(pyca) Grey >300 15.11 17.43 5.0<' 338.1(15.38) 07.95) (357.2)Mn(tsc).(et.dtc) Greyish-brown >300 14.43 33.01 4.93 369.8(14.32) (33.43) (357.2)Mn(acac).(pyca) Grey 150 14.43 4.92 349.0(14.63) (375.2)Mn(acacnpyca), Pink 160 13.74 5.08 437.1• (13.79) (398.2)751INDIAN J. CHEM .• VOL. 20A, JULY 1981Il[ 1H2HN-C.i >;~N SINH21I IN=C11/ \H2N SH(J[ )(I)be explained if the band is indeed a N-N vibration.In a symmetrical molecule, the N-N vibration isinfrared forbidden. In the neutral ligand it should beallowed but is probably very weak. For the uni-ne-gative ligand, however, the vibration becomes moreintense and this is explained by the X-ray studies-?which show that the C = N double bond is almostcompletely localized in the C-NIl region. Hence,the Nll and Nm atoms are very much different.The position of the band at lower energy is also con-sistent with the observed lengthening of the NILNllI bond. In all the three thiosemicarbazido com-plexes, in addition to bands due to a(NH), amide,v(CN) + a(NHII) and v(C =S), a sharp band appearsat 950 crrr? indicating uninegative bidentate natureof the ligand=". Dithiocarbamate can behave as abidentate or a monodentate ligand. The former exhi-bits \I(CS) near 1000 em'? as a single band, whereasthe latter shows a doublet in the same region-",Also the v(C = N) of the former (above 1485 cm ")is higher than that of the latter (below 1485 cm-1)12.In the present case, the ligand dithiocarbamate exhi-bits v(C= N) band at 1505 crrr? and a singlet at 1005crrr? due to vas(CS) indieating that the chelate is coor-dinated to manganese(III) ion through both the sul-phur atoms as a uninegative bidentate ligand. Similarobservations for manganese tris (dithiocarbarnates)have been reported by Prabhakaran and Patel-"and Das and Ramana Rao-". In the acetylacetonatocomplexes, the bands due to \I(C .:.:..:0)and v(C ::..:...C)were obtained at ,.....11600 and 1520 cm-l respectivelyindicating the uninegative bidentate coordinationof the ligand as suggested by Graddon=. In thecompounds containing picolinate group, theband due to free carboxyl group at 1710 cm-1 wasfound to be absent. Other bands due to \las(CO.O)and pyridine ring were found to be present indicat-ing the coordination of the ligand through the nitrog-en and oxygen atoms as an uninegative bidentateone as suggested by Fowles et alP:The electronic spectra of the complexes show threebands at '" 13500, ,.....22900, and ,.....25000cm=. Onlyone spin-allowed transition 5Eg -+ 5T'log is expectedfor weak field octahedral manganese(III) com-plexes17,18. The presence of three bands in these com-plexes indicates lowering of the Oh symmetry dueto Jahn-Teller distortion The complexes are expec-ted to be tetragonally distorted with D 4h symmetryand the bands can be assigned to the transit-ions, 5B1g -+ 5Alg (,.....13500 crrr<), 5B]g -+ 5B2g(,....22900 cnr") and 5Blg -+ 5Eg (,....25000 crrr+) assuggested by Davis et al.19• and Lever''". The lowestband of all the complexes was found to be broadwhich confirms the Jahn-Teller distortion experien-752ced by these complexes. Thus, in the light of theabove evi.dences, it is suggested that the five mixedchelate manganese(III) complexes reported here aresix-coordinated with tetragonally distorted octahed-ral stereochemistries.One of the authors (B.P.) is thankful to the Edu-cation Ministry, Government of India for a researchgrant.References1. DAs, A. K. & RAMANARAo, D. V., Cherny. Ind., 20 (1975).792.2. BARTLETT,M. & PALENIK,G. J., Chern. Commun., (1970),416.3. RAY, M. M., AoHYA, J. N., PODDAR, N. G. & PODDAR.S. N., Aust . J. Chem., 21 (1968), 801.4. ISOBE,K. & KAWAGUCHI,S, Bull. chem. Soc. Japan, 48(1)(1975), 250.5. STULTS,B. R., DAY, R. 0., MARIANELLI.R. S. & DAY.V. W., Inorg. Chem., 18 (1979), 1847.6. STULTS,B. R., MARIANELLI.R. S. & DAY, V. W., Inorg.Chem., 14 (1975), 722.7. LIVINGSTONE,S. E., Q. Rev. chem, Soc., 19 (1965), 415.8. HAINES,R. A. & SUN, K. K. W .• Can. J. chem., 46 (1968),3241.9. PANDEY,U. N., J. Indian chem, Soc., 54 (1977),579.10. CAVALCA,L., NARDELLI,M. & FAVA,G., Acta. Crystallogr.,15 (1962),1139.11. BONATr,F. & UGO, R., J. organometal. ehem., 10 (1967),257.12. O'CONNOR, C., GILBERT,J. D. & WILKINSON,G., J. chem.Soc., (1969), 84.13. PRABHAKARAN,C. P. & PATEL,C. C., Indian J. Chern. 1(1969),1257.14. DAs. A. K. & RAMANARAO, D. V., Indian J. Chem., 13(1975), 620.15. GRADDON,D. P., Coord. chem, Rev.,4 (1969), 1.]6. FOWLES,G. W. A., MATTNEWS,R. W. & WALTON,R. A .•J. chem, Soc., (1968), 1108.17. BALLHAUSEN,C. J .• Introduction to ligand field theory(McGraw-Hill, New York), 1962. .18. FORLANI,C. & CIANO,A., Ann. Chim., 48 (1958), 286.19. DAVIS,T. S., FACKLER,J. P. & WEEKS,M. J., Inorg. Chem .•7 (1968),1994.20. LEVER,A. B. P., Inorganic electronic spectroscopy (ElsevierPublishing Co., Amsterdam), 1968, 290.Polarographic Studies on Mixed Ligand ComplexesInvolving Amino Acids : Ternary Systems, Cd-IX.-Alanine-Oxalate & Cd-~-Alanine-OxalateANITARANI AGGARWAL,.K.B. PANDEYA& R. P. SINGH.Department of Chemistry, University of Delhi, Delhi 110007Received 7 October 1980; revised and accepted 14 November1980Ternary complexes of cadmium(II) with oxalate as primaryligand and (X- and ~-alanines as secondary Iigands have beenstudied polarographically. Formation of three mixed complexspecies, [Cd(amino acid) (oxalate)], [Cd(amino acid) (oxalatejj]and [Cd(amino acld), (oxalatej], is observed in each case. Thereduction is reversible and diffusion-controlled. The stabilityconstants have been evaluated using the method of McMasters.The (X-alanine complexes are found to be more stable than thecorresponding ~-a\anine complexes.

Mixed Chelate Complexes of Manganese(III)

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Mixed Chelate Complexes of Manganese(III)

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