NOTES

TABLE 1 - ANALYTICAL DATA OF THE COMPLEXES

S (%) Metai(%) N(%)

Found Calc. Found Calc. Found Calc.

27.03 26.91 12.13 12.34 8.67 8.8315.07 15.00 6.53 6.88 4.65 4.9222.20 22.12 10.04 10.14 14.37 14.5113.46 13.38 6.21 6.14 8.62 8.1824.15 24.68 11.39 11.31 10.67 10.8024.78 24.68 11.22 11.31 10.73 10.8014.35 14.27 6.41 6.55 6.13 6.25

Complex

Ni(Me.dtp).(dien)Ni(MeCidtpi).(dien)Ni(dien).(Me.dtp)2N i(dien)2(MeCld tp i).Ni(Me.dtp)2(trien) (Green)Ni(Me2dtp)2(trien) (Blue)Ni(MeCldtpi).(trien)

indicate the presence of NiN8 chromophores withboth dithio groups placed outside the coordinationsphere.

Interaction of trien with Ni(Me2dtp)2 producedtwo new 1: 1 green and blue coloured compoundshaving magnetic moments of 2.86 and 2.71 B. M.respectively. The reflectance spectrum of the bluederivative showed absorptions at 16950 and 21740.Taking its solubility in water, r~flectance. spec~raldata and conductivity (87.7 0) into considerationit is expected to have a structure with NiS4N2 chro-mophore where one dithioligand is 0l:ltsi~e the ~o-ordination sphere. For the green derivative whichis soluble in organic solvents the electronic spectrumin chloroform exhibited bands at lower wave numbers[15150 (67) and 19230 (12)] and this may be due tostrong sulphur coordination which have a lowerposition in the spectrochemical series. These facto~slead to the possibility of a NiS4N2 chr?moph?re inthis complex. Similar results were obtained with thedithiophosphinato derivative; however, the. bluecompound in this case could not be isolated m t~esolid state and the light green complex had a magneticmoment of 2.84 B. M. Its electronic spectrum inchloroform exhibited bands at 14290 (38) and 19180(18). . .

Attempts to isolate 1:2 complexe.s with tI~Ien r~sul-ted in the formation of an unidentifiable pink stickymass. The solution spectral features were similarto those of 1:2 adducts with dien.

In the IR spectra the broad bands observed around3120 3430 and 1550 were assigned to NH2 stretch-ing ~nd bending vibrations respectively.. ~he. diffe-rence in the donor behaviour of the dithio-ligandscould not be distinguished from the IR spectra inwhich vP-S vibrations were observed around 510,650 and 700. The weak band observed around 410for the 1:2 complexes was assigned to vM-N.

References1. MUKHERJEE, R. N. & ZINGDE, M. D., Indian J. Chem.,

10 (1912), 941.2. MUKHERJEE, R. N., VENKATESHAN, M. S., ZINGDE, M. D.

& DHINGRA, M. M., J. inorg . nucl. Chem., 38 (1916),689.

3. CRAYTON, P. H. & MATTERN, J. A., J. inorg . nucl. Chem.,13 (1960), 248.

4. HIGGINS, W. A., VOGEL, P. W. & CRAIG, W. G., J. Am.chem. Soc., 77 (1955), 1864.

5. COLDBERRY, D. E., FIlRNELIUS, W. C. & SHAMMA, M.,Inorganic Syntheses, Vol. 6 (1960), 142.

6. STEPHENS, F. A., J. chem, Soc. (A), (1969), 883.7. BIAGINI, S. & CANNAS, M., J. chem. Soc. (A) (1970), 2398.

2,2'-BipyridyI & 4,4'-BipyridyI Complexes withMo(II), Co(II), Ni(II), Cu(II), Zo(II) & Cd (II)

Acetates

I. S. AHUJA* & C. L. YADAVA

Department, Banaras Hindu University,Varanasi 221 005

andRAGHUVIR SINGH

School of Chemistry, University of Hyderabad,Hyderabad 500134

Chemistry

Received 21 January 1981; revised and accepted 12 March 1981

Complexes of Mn(II), Co(ll), Ni(II), Cu(ll), Zn(I1) andCd(II) acetates with 2,2'-bipyridyl (2,2'-Bipy) and 4,4'-bipyridyl(4,4'-Bipy) have been prepared in the solid state and characterisedon the basis of their magnetic susceptibilities, electronic and IRspectral measurements. Their tentative stereochemistries arsdiscussed. Ligand field parameters - 10 Dq, B, Dq/B, t), V,/Viand C.F.S.E. - calculated for the Co(ll), and Ni(11) complexesare consistent with their proposed stereochemistries.

ALTHOUGH a variety of complexes formed bytransition and non-transition metal(II) salts

with nitrogen donor ligands have been studied,very few acetate complexes of these metal ions areknown. This may be due to the fact that the donorability of the acetate group is weaker than that ofwater and it is only recently that the acetate com-plexes of some metal(II) ions are described.':". Wereport here the preparation and characterization ofMn(II) Co(H) Ni(II), Cu(II), Zn(II) and Cd(II)acetate' compl~xes with 2,2'-bipyridyl (2,2'-Bipy)and 4,4'-bipyridyl (4,4'-Bipy).

Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II)and Cd (II) acetates with 2,2' -Bipy and 4,~' -BIPYwere obtained by mixing together hot soll:ltlOns ?fthe appropriate metal acetate and the ligand 111

ethanol. The complexes, which precipitated outimmediately or crystallized out on cooling, weresuction-filtered washed with ethanol, anhydrousether and finally dried at _70°C. The nickel andcadmium complexes were dried at _110°C. Stoi-chiometries of the solid complexes isolated wereobtained by standard analytical methods. .

Electronic spectra of the Mn(H), Co(II), Nl(II)and Cu(II) complexes were recorded in nuj.ol in therange 33000-6000 cm-1 on a Cary 14 recording spec-trophotometer. IR spectra of the ligands and their

1127

INDIAN J. CHEM., VOL. 20A, NOVEMBER 1981

complexes were recorded in nujol supported betweensodium chloride plates (rock salt region) and thinpolythene sheets (650-200 crrr-') on a Perkin-Elmer621 spectrophotometer equipped with caesium iodideoptics. Magnetic susceptibilities were measured atroom temperature by the Faradays' method witha Cahn R. G. Electro-balance model 7550 usingHg[Co(NCS)4] as the standard. Pascals' constantswere used for diamagnetic corrections.

The complexes prepared, their analytical data andthe characteristic IR bands due to coordinatedacetate groups are given in Table 1. Magneticmoments, electronic spectral data and the ligandfield parameters are listed in Table 2. No absorp-tion bands were observed which could be attributedto water or ethanol in any of the spectra thus esta-blishing that these compounds are free from coordi-nated or lattice water/ethanol.

IR spectra of the complexes studied here indicateclearly that both the donor sites of 2,2' -Bipy arebonded to the same metal ion resulting in the for-mation of five-membered rings3'4. However, IRspectra of the 4,4' -Bipy complexes indicate that boththe nitrogens of this ligand are bonded to differentmetal ions and that 4,4' --Bipy acts as a bridge bet-ween two metal ions. The steric position of the twonitrogen atoms in 4,4' -Bipy precludes chelation butfavours coordination to two different metal ions thusleading to polymer chain formation.

Manganese(Il) complexes - Because of the addi-tional stability of the half filled d-shell Mn(H) gene-rally forms high-spin complexes. Since the high-spin Mn(H) complexes have an orbitally degenerate6hs ground state term, the spin-only magnetic momentof 5.92 B. M. will be independent of the temperatureand of the stereochemistry. The 1 :1 Mn(Il) acetatecomplexes with 2,2'-Bipy and 4,4'-Bipy have roomtemperature magnetic moments of 5.77 and 5.90

B. M., respectively, indicating that these are high-spin complexes. IR spectra of both these complexesexhibit bands at ",1560, 1410 and 650cm-1 (Table 1)due to Vas OCO, Vs OCO and aoco modes, res-pectively. The 2,2'-Bipy complex shows two bandsdue to vsOCO vibrations (due to the cis dispositionof the two acetate groups, vide infra). The frequen-cies of these modes and the separation ( 140 cnr-')of the Vas OCO and vs OCO modes strongly suggestthe exclusive presence of symmetrically coordinatedbidentate chelating acetate groups in both thesecomplexes" 2'5 . From the considerations that (i)2,2' -Bipy is coordinated in a bidentate chelatingfashion and 4,4' -Bipy as a bidentate ligand bridgingthe two metal ions, (ii) the acetate groups are bondedas bidentate chelating ligands, and from the dis-cussion of their magnetic moment values, the tenta-tive stereochemistries postulated are : (a) six-co-ordinated monomeric high-spin octahedral environ-ment of two nitrogen atoms of the 2,2' -Bipy moleculeand four oxygen atoms of the two chelating acetategroups (cis to each other) around the metal atomsin the 1: 1 Mn(H) acetate-2,2' -Bipy complex and(b) polymeric high-spin octahedral environmentaround Mn(H) in the 1:1 Mn(H) acetate-4,4'-Bipycomplex with the two acetate groups trans to eachother in the solid state.

Cobalt(JI) complexes - Cobalt (II) acetate formed1:1 complex with 4,4'-Bipy only. It showed mag-netic moment value of 4.70 B.M. indicative ofoctahedral coordination. Its electronic spectrumshows two main bands at 10260 and 21050 cm-Iwith shoulders on either side. These bands areassigned to the transitions 4TIg (F) --+ 4T2g (F) (VI)and 4TIg (F) --+ 4T]g (P) (V3)' respectively, charac-teristic of a weak octahedral field around coba ltffl)".The following equations? were applied to calculateDq and BQ the Racah parameter :

TABLE1 - ANALYTICALANDIR SPECTRALDATA (cm") OF THECOMPLEXES

Sl Found (Calc.), %No. Compound vas OCO ~s OCO 1) OCO

Metal C H

1. Mn(2,2' -Bipy)(OAe)2 16.3 51.0 4.4 1540s 1450s 645ms(16.1) (51.1) (4.3) 1410s

2. Mn(4,4'-Bipy)(OAe)2 16.9 51.3 4.4 1580s 1430s 640ms

Co(4,4'-BipY2)(OAe)2(16.7) (51.1) (4.3)

3. 17.7 50.2 4.3 1580s 1435s 665m(17.7) (50.4) (4.2)

4. Ni(2,2' -Bipy)(OAe)2 12.0 58.4 4.6 1545s 1440s 650m

Ni2(4,4'-BipyMOAe).(12.1) (58.9) (4.5)

5. 14.3 55.6 4.6 1520s 1450s 630m

6. Cu2(4,4'-Bipy),(OAe).(14.3) (55.9) (4.4)15.4 54.6 4.5 1560s 1450s 645ms

Zn(2,2'-BipY)2(OAe)2(15.2) (54.8) (4.3)

7. 13.5 58.2 4.5 1550s 1450s 673ms

8: (13.2) (58.1) (4.4) 1430sZn(4,4'-Bipy)(OAe)2 19.4 49.3 4.4 1580s 1430s 665ms

9. Cd(2,2'-Bipy),(OAe),(19.2) (49.5) (4.1)20.9 53.4 4.1 1550s 1450s 665ms

(20.7) (53.1) (4.0) 1430s10. Cd(4,4'-Bipy)(OAc), 29.3 43.2 3.8 15605 1410s 665ms

(29.1) (43.5) (3.6)

10 Dq = 2Vl- V3+ 15 B = 10397 cnr+B = 1/30 [-(2Vl - V3)± { -vi + v5 + VIvJ!]

= 728 cm-1The value of B (728 em?") is considerably less

than the free ion value (971 crrr-') which is an indi-cation of orbital overlap and deloca1ization of thed-orbitals. The fundamental frequencies due toacetate groups (Table 1) in this compound are con-sistent with their bidentate chelating nature-e.Based upon the magnetic moment value, electronicand IR spectral data the 1:1 Co(II) acetate-4,4'-Bipycomplex is tentatively assigned a six-coordinated,polymeric octahedral structure with four oxygenatoms from the two acetate groups (trans to eachother) and two nitrogen atoms from the bridging4,4' -Bipy molecules around the Co(II) ions in thesolid state.

Nickel(JI) complexes - Nickel(II) acetate formeda 1:2 complex with 2,2'-Bipy and a 2:3 complexwith 4,4'-Bipy. Both these compounds possessroom temperature magnetic moments ,.....,3.0B. M.Electronic spectra of these compounds exhibit bandsat ,.....,9750,and ,.....,15800cm-1 which are assigned tothe transitions 3A2g -* 3T211 (VI) and 3A2g -*3T1g (F) (V2),respectively, assuming octahedral fieldaround nickelrIl)?". The value of 10 Dq was takenas that of the lowest energy transition 3A2g -* 3T2g

(Table 2). B, the Racah parameter was calculatedfrom the relationship developed by Konig". ForNi(II) ion the spin-orbit coupling causes an orbitalcontribution in the quenched 3A2g aground state togive a high value of the magnetic moment com-pared to the spin-only value of 2.84 B.M. Theinfluence on p. is of the second order perturbationand is quantitatively defined by the relation : P.obs

= p.&'o ( 1- 4104~q) where IAI is the spin-orbit

coupling constant. Substituting the value of 10 Dqwe obtain 1>'1 values of 188 and 154 cm-I for the2,2'-Bipy and 4,4'-Bipy complexes, respectively.Compared with the free ion value of 324 cm-1there is a considerable reduction (,.......50%) in A valuewhich indicates the high orbital contribution andcovalent character. The value of v2/vI, obtainedfor both these complexes is lower than 1.8, the valuefor a regular octahedral species [Ni(H20)6P+' Thelowering may be attributed to the asymmetric environ-ment around Ni(II) in these complexes and somedistortion from the regular 0" symmetry. TheB values - 914 and 849 cm-I (Table 2) - forthese compounds are also less than the free ion valueof 1041 crrr+ which again is an indication of orbitaloverlap and delocalization of the d-orbitals. IRfrequencies due to acetate groups (Table 1) suggestthe exclusive presence of terminal monodentateacetate ligands in both these compounds. Based onthe magnetic moment values, electronic spectral,ligand field data and the mode of metal-acetatebondings the tentative stereochemistries suggestedare : (i) a monomeric, six-coordinated structure withan octahedral environment of four nitrogen atoms(from two 2,2'-Bipy molecules) and two oxygenatoms (from two terminal mono dentate acetate

NOTES

TABLE 2 - MAGNETIC MOMENTS(B.M.) AND ELECTRONICSPECTRALDATA

Complex Complex Complex Complex3 4 5 6

v, (crrr ') 12060 9705 9756 13790v. (crrr ') 15880 15800V3 (cm") 21050[.I..1f (B.M.) 4.70 3.06 3.02 1.76v./vi 1.63 1.6110 Dq (cm") 10397 9705 9756B (crrr ') 728 914 849~ 0.750 0.878 0.874oet» 1.42 1.06 1.15C.P.S.E. 17.7 33.2 33.3-I. 188 154

groups) for the 1:2 Ni(II) acetate-2, 2'-Bipy complex,and (ii) a polymeric, six-coordinated structure withan octahedral environment of four nitrogen atoms(from bridging 4,4'-Bipy molecules) and two oxygenatoms (from two terminal mono dentate acetategroups) around the metal atoms in the 2:3 Ni(II)acetate-4,4' -Bipy complex in the solid state.

Copper(JI) complex - Copper(II) acetate gave a2:3 complex with 4,4'-Bipy only. The observedmagnetic moment value (1.76 B. M.) for this complexis less than the expected value (l.93 B. M.) sugges-ting weak interactions or polymeric nature of thecompound. Electronic spectrum of this compoundshows a strong band at 13790 cm-1 which may bedue to overlapping of three transitions expected in adistorted octahedral field-". IR spectrum of thiscompound is consistent with the exclusive presenceof terminally bonded monodentate acetate groups.Based upon the above considerations a six-coordi-dinate, polymeric, pseudo-octahedral geometry istentatively suggested for the 2:3 Cu(II) acetate-4,4'-Bipy complex in the solid state.

Zinc(JI) and cadmium(ll) complexes - Bothzinc(II) and cadmium(II) acetates gave 1:2 complexeswith 2,2'-Bipy but 1:1 complexes with 4,4'-Bipy.Since electronic spectral and magnetic momentstudies are not possible in these cases, the charac-terization of these complexes is based mainly ontheir analytical and IR spectral data. IR spectraclearly indicate that 2,2' -Bipy acts as a bidentatechelating ligand while the isomeric 4,4' -Bipy acts asa bidentate bridging ligand in these complexes.IR frequencies due to acetate groups suggest theexclusive presence of terminal monodentate Iigands="in the 1:2 Zn(II) and Cd(II) acetate-2, 2' -Bipy com-plexes and bidentate chelating ligands in the 1:IZn(II) and Cd(II) acetate-4,4' -Bipy complexes.Based on these considerations the tentative stereo-chemistries suggested are : (i) six-coordinate, mono-meric octahedral structures for the 1: 2 metaklf)acetate-2,2'-Bipy complexes (with the two terminallybonded mono dentate acetate groups cis to eachother), and (ii) six-coordinated polymeric octahedralstructures for the 1:1 metal(II) acetate-4,4' -Bipycomplexes (with two bidentate chelating acetategroups trans to each other) in the solid state.

1129

INDIAN J. CHEM., VOL. 20A, NOVEMER 1981

We thank Prof. B. M. Shukla, Head of theChemistry Department, B. H. D., for providingfacilities.

References1. CURTIS, N. F., J. chem, Soc., (A) (1968),1579.2. AHUJA, I. S. & RASTOGI,P., J. chem. Soc.,(A) (1970), 2161;

AHUJA, I.S. & GARG, A., 1110rg.chim. Acta, 6 (1972), 453;AHUJA, 1. S. & SINGH, RAGHUVIR,lnorg. chim. Acta, 7(1973), 565; AHUJA, 1. S., SINGH, RAGHUVIR &SRIRAMULU,R., J. molec. Structure, 53 (1979), 301.

3. McKENZIE, E. D., Coord. chem. Rev., 6 (1971), 187.4. FERRARO, J. R. & DAVIS, K. c., Inorg . chim. Acta, 3

(1969), 685.5. NAKAMOTO,K., Infrared and raman spectra of inorganic &

coordination compounds (John Wiley, New York), 1971,230.

6. JORGENSEN,C. K., Absorption spectra and chemical bondingin complexes (Pergamon Press, London), 1962, 285.

7. KONIG, E., Structure & Bonding, 9 (1971), 175.8. TANABE,Y. & SUGANO,S., J. phys. Soc., (Japan), 9 (1954),

153, 766.9. LIEHR, A. D. & BALLHAUSEN,C. J., Ann. Phys., New York,

6 (1959), 134.10. HATHAWAY,B. J. & TOMLINSON,A. A. G., Coord. chern.

Rev., 5 (1970), 1.

Manganese(II & III) Complexes of Schiff BasesContaining ONO Donors

B. R. HAVINALE*& I. B. PUJARDepartment of Chemistry, Karnatak University,

Dharwad 580 003

Received 8 January 1981; revised and accepted 20 March 1981

Manganese(1I & III) complexes of schiff bases derivedfrom 2-hydroxy-l-naphthylmethylamine and salicylaldehyde andits derivatives have been synthesized and characterised on thebasis of magnetic and spectral data. The elemental analyses show1 : 1 (metal-ligand) stoichiometry indicating the dibasic behaviourof the ligands. The infrared spectral study reveals the tridentatenature (ONO) of the ligands. The complexes exhibit magneticmoments below the spin-only value attributable to the dimeric natureof the complexes. On the basis of magnetic and spectral data,dimeric octahedral and square-pyramidal structures for manga-nese(1I) and manganese(III) complexes respectively with naph-thylmethylaminophenolic oxygen atoms as the bridging atoms aresuggested.

MANGANESE(III) complexes have been muchless studied than chromium(III) and cobalt(III)

complexes. This is presumably due to the factthat the 3d4 high-spin configuration is susceptibleto oxidation-reduction reactions'. The trivalentstate of the element in the complexes is howeverstabilised in the presence of chelating ligands dueto the change of the properties of the free ion bythe ligand environment". Thus, many stable com-plexes of Mn(III), most of them of high-spin type,have been synthesized with a variety of schiff basesv-.

The recer.t interest in the study of manganese(II& III) complexes with different types of ligandsis due to their biological importance". The recentdiscovery" of manganese containing version of dis-mutase has been in fact a good stimulus for the

1130

growing interest in the study of manganese/If & III)complexes".

The present note describes the synthesis andcharacterization of manganese(II & III) complexeswith the schiff bases (I-V).

~ r0t-~OH HOY R

CH2-N= CH

I, R=Hzr, R=5-CH3zrr, R =3-0CH3I, R::.5,6 -C6H4

Salicylaldehyde, o-hydroxyacetophenone and 0-

vanillin were S. Merck ,Aldrich and BDH reagentsrespectively. 2-Hydroxy-l-naphthaldehyde8, 2- hyd-roxy-l-naphthylmethylamine hydrochloride and5-methylsalicylaldehyde9 were prepared accordingto literature methods. Manganese(III) acetate dihy-drate was prepared by the known method-". Manga-nese(II) acetate tetrahydrate was an AR grade re-agent. The schiff bases were prepared by thereaction of the amine (O.IM) and the correspondingaldehyde (O.IM) in ether and recrystallized frommethanol.

Preparation of complexes - To an ethanolic solu-tion (0.1M) of base hydrochloride and the corres-ponding aldehyde (0.1M), an ethanolic solution ofsodium hydroxide (0.3 M, slightly less than required)was added with vigorous stirring and the contentswere boiled on a water-bath until a clear reddish-yellow solution was obtained. To this solution anethanolic solution of manganese(III) acetate (O.IM)was added slowly with constant stirring to get thereddish-black precipitate which was washed withthe minimum quantity of ethanol and ether anddried over anhydrous calcium chloride. Similarlymagnanese(II) complexes were prepared.

Manganese in the complexes was estimated aspyrophosphate-'. Nitrogen was estimated byKjeldhal's method. Thechloridecontent in Mn(III)complexes was estimated by Volhard's rnethod-",

The conductance measurements were done on anELICO CM-82 conductivity bridge with a cell havinga cell constant of'Ojiza crrr-'. The magnetic measure-ments were made on a Gouy balance at room tem-perature using Hg[Co(SCN)4] as the calibrant. Theelectronic spectra of complexes were recorded innujol mull on a Beckmann-DMR-21 spectrophoto-meter in the region 300-1000 nm. The IR spectrawere recorded on a Perkin-Elmer-257 spectrophoto-meter in KBr in the region 4000-650 cm-1 and on aPerkin-Elmer-577 spectrophotometer in nujol mullin the region 650-200 crrr-'.

Mn(II) complexes are light-pink whereas Mn(III)complexes are reddish-black. MnCIII) complexesare more soluble than Mn(II) complexes in methanoland DMF. The elemental analyses show (Table l)that the complexes have 1:1 (metal-ligand) stoichio-metry indicating dibasic behaviour of the schiff bases.Mn(II) complexes are of the type [MnL(H20)2]2