Indian lournal of ChemistryVol. 33A, October 1994, pp. 908-913

Synthesis and characterization of copper(II), cobalt(II&III) and nickel(II)complexes with ferrocenyl schiff bases

Kamalendu Dey* & Kartik Kumar NandiDepartment of Chemistry, University of Kalyani, Kalyani 741 235

Received 311anuary 1994; revised 28 April 1994; accepted 241une 1994

A few ferrocenyl schiff bases have been isolated by the condensation of forrnylferrocene and ace-tylferrocene with ortho-phenylenediamine, ortho-aminophenol and ortho-aminobenzoic acid. Reactionsof these ferrocenyl schiff bases with copper(II), cobalt(II) and nickel(II) salts in varied reaction condi-tions yield new complexes of the type M(L)"2and also some mixed ligand complexes of the typeM(L)(X)(NH3) (where HL is mon -basic bidentate ferrocenyl schiff base, M = Ni(II), Cu(II), Co(II)and X=(OH/Cl). Cobalt(III) complexes of the type Co(L}z(OH)(NH3) are also isolated. The com-pounds have been characterised on the basis of elemental analyses, molar conductance, molecularweights, magnetic susceptibilities and spectroscopic (electronic and infrared) data.

Although the chemistry of metal complexes ofschiff bases have been extensively studied overthe past years, the metal complexes of ferrocenecontaining schiff bases have not been thoroughlyinvestigated. It is only recently that some reportson the complexing behaviour of ferrocenyl schiffbases have been reported 1-4. There is a possibilitythat the ferrocenyl schiff bases and their metalcomplexes might have redox active propertiesand also would have applications in non-linearoptics and other areas of molecular electronics. Inview of the multiferous importance of ferrocene,ferrocenyl chelating ligands and also their metalcomplexes>, we have synthesised several ferroce-nyl schiff bases by the condensation of formylfer-rocene and acetylferrocene with artho-phenylene-diamine, artho-aminophenol and artho-aminoben-zoic acid to study their complexing behaviour.This paper describes the isolation and characteri-sation of new ferrocenyl schiff base ligands(Structure I) and their complexes with copper(D)cobalt(II), cobalttlll) and nickel(II) ions.

Of these six schiff bases, only HFfaa and HAfa-ba were isolated in the solid state and used in thepreparation of metal complexes. The metal com-plexes of other schiff bases were prepared by insitu method.

Materials and MethodsFormylferrocene and acetylferrocene (Fluka

and Sigma Chemicals) were used as such andthese were also synthesized by the literature

MeOH or CHCI,REFLUX -Acetic Aci d orPet.~r

R : H/CH, HFfoa ; when, R: H c.ld R':-aC.H4-NHatWaa; when ,R: CH, c.ld 1t'-ac.H4-NH2HFfop ; when ,R=Hand R':-aCIH4-0HHAfop ; when, R. CH, and It. -iCtH4 - OHHFfaba;when , R= Hand R" -ICaH4-COOHHlifoba;whit/\, R. CH, and R'. -~-COOH

STRUCTURE I

method". The solvents were purified and driedbefore use by standard procedures 7•

Preparation of the ligands

1-{ N-2( amino )anilineiminemethynfe"oceneFormyl ferrocene (0.001 mol) was dissolved in

dry methanol (50 em") and ortho-phenylenedia-mine (0.001 mol) in methanol (50 cm ') was addedto it with stirring. The mixture was heated underreflux for 4 h after addition of a few drops of gla-cial acetic acid. The brown solution was thencooled to - lOoC, whereby a yellow crystallinecompounds separated out. It was filtered off,washed with dry methanol and dried in vacuo,yield 70%; m.p. 150°C (dec.).

1-{ N-2( carboxylianilineimine ethytferroceneTo the chloroform solution (50 ern") of acetyl-

ferrocene (0.001 mol) was added a solution of

DEY et al: Cu, Co & Ni COMPLEXES WITI-I FERROCENYL SCHIFF BASES 909

orthlraminobenzoic acid (0.001 mol) in chloroform(50 ern") with stirring .and the mixture heated un-der reflux for 6 h. The solution was then cooledto room temperature and pet. ether (40-60°) wasadded dropwise whereby a brown precipitate ofHAfaba appeared, which was recrystallised fromchloroform pet-ether mixture, yield 60%; m.p.210°C (dec.).

Preparation of complexesAll the complexes were isolated by in situ

method. The ligands HFfaa and HAfaba were al-so used for the preparation of complexes andwere found to produce identical complexes com-pared to in situ preparation. The preparation issummarized below:

To an ethanolic solution (60 crn') of HFfaa(0.001 mol) [or HAfaa prepared in situ by thecondensation of acetylferrocene and orthopheny-lenediamine (0.001 mol) in ethanol] was addedthe metal salt solution (0.001 mol) in ethanol (40cm ') and the mixture heated under reflux at pH- 9 (15% NH40H) for 2 h on water bath. Thefollowing complexes were isolated, which were fil-tered and washed with suitable solvents.

Ni(Ffaah2HzO (1), orange yellow crystals(yield 60%) soluble in common organic solvents.Ni(Afaa)22H20 (2), brown crystals (yield, 65%),soluble in organic solvents, Co( Ffaah (3), blueviolet solid (prepared under nitrogen atmosphere),(yield, 65%). Co(Afaa)2 (4), violet solid (preparedunder nitrogen atmosphere, (yield, 65%).Co(Ffaa)2 (Off) (NH3) (5), brown (prepared in ex-cess of air), yield 80%. C6(Afaah( Off)(NH3) (6),brown (prepared in excess of air), (yield 80%).Cu(Ffaah (7), brown, (yield, 70%). Cu(Afaah (8),brown, (yield, 70%). CU(Afaa)z (NH3h (9), isolat-ed from the filtrate of compound (8) on treatingwith excess NH40H as deep brown compound,(yield, 25%).

Similarly the complexes (10) to (18) were pre-pared by in situ method.

Ni(Ffap) ict, (NH3), (10), brown, (yield, 65%).Ni(Ffap) (Off) (NH3), (11), brown, (yield, 65%).Ni(Afap) (Cn (NH3), (12), brown, (yield, 70%).Co(Ffaph (Off) (NH3), (13), deep brown (pre-pared in excess of air), (yield, 65%). Co(Ffap) (Cn(NH3), (14), brown complex (prepared in dry sol-vent under nitrogen atmosphere), (yield, 60%).Cu(Ffap) (Off) (NH3), (15), brown, (yield, 70%).Ni(Ffaba) (Cn (NH3), (16), red (yield, 70%).Ni(Afaba) (Cn (NH3), (17), reddish brown, (yield75%). Cu(Ffabf!-) (Cn (NH3), (18), brown, (yield65%). '

Results and DiscussionThe reactions of l-formylferrocene and l-ace-

tylferrocene with orthlraminoaniline (orthlrpheny-lenediamine), orthlraminophenol and orthlramino-benzoic acid in ethanol and in the presence ofglacial acetic acid produced coloured ferrocenylschiff base HFfaa, HAfaa, HFfap, HAfap, HFfabaand HAfaba respectively in solution (Structure I).However, only HFfaa and HAfaba could be iso-lated in the pure state. Therefore, in situ prepara-tive methods were employed for the syntheses ofthe metal complexes. However, repetition of pre-paration with HFfaa or HAfaba afforded thesame complexes as obtained by in situ method.

The reactions of Ni(OAc)24H20 or NiCl26H20with HFfaa and HAfaa in ethanol at pH - 9yielded schiff base complexes (1) and (2) respect-ively.

The identical reactions of CUtOAc )2H20 withHFfaa and HAfaa at pH - 9 yielded complexes,CU(Ffaah, (7) and Cu(Afaah, (8) respectively. It isinteresting to note that the filtrate from (8), onprolong standing in the presence of excessNH40H, yielded a complex, Cu(Afaalz(NH3lz, (9).

The reaction of NiCI26H20 with the refluxedsolution of formylferrocene (or acetylferrocene)and orthlraminophenol in ethanol at pH - 9yielded Ni(Ffap) (Cl) (NH3), (10) or Ni(Afap) (Cl)(NH 3)' ( 12). On the other hand, the use ofNi(OAch4HzO at pH - 9 in place of NiClz6HzOyielded the complex Ni(Ffap) (OH) (NH3), (11).

Similarly in situ reactions of the ligand compo-nents and CO(OAC)24H20 at pH - 9 (in excess ofair) afforded a cobalt(lII) complex, Coiffapj,(OH) (NH3), (13). The same reaction withCoCI26H20 under nitrogen atmosphere, however,gave Co(Ffap) (Cl) (NH)), (14).

Similarly, formylferrocene or acetylferrocenereacts with ortho-aminobenzoic acid in the pres-ence of NiCl26H20 yielding diamagnetic nickel(H)complexes Ni(Ffaba) (Cl) (NH,), (16) and Ni(Afa-ba) (CI) (NH3), (17) at pH - 9. The replacementof NiCI26H20 by CuCI2H20 under identical reac-tion conditions gave the copper(II) complex,Cu(Ffaba) (CI) (NH3), (18).

The preparations are summarized in Schemes1-3.

The isolated Jigands and complexes are all co-loured and stable at room temperature. The li-gand HFfaa decomposed at 150°C, while HAfabadecomposed at 210°C. The complexes did notmelt upto 200°C. The elemental analyses of thesolid ligands and the newly synthesized complexesagreed with their formulations (Table 1 andSchemes 1-3). The molecular weights of some of

910 INDIAN J CHEM, SEe. A, OCTOBER 1994

Table 1 - Characterisation data of the ligands and their complexesCompounds Mol.

weight Colour Found (Calc.) % Q - 'cm2mole-' !lelfweight A.M (B.M.)

C H N Cl MHFfaa Light 67.14 4.78 8.78

C'7H'oN,Fe Yellow (67.13) (5.26) (9.21 )

HAfa1::a Brown 64.89 5.21 4.12

C,yH1702NFe (65.73) (4.90) (4.03)

Ni(Ffaa)22H20, (1) 689 Yellow 58.oI 4.62 8.21 8.52 3.25 Diamagnetic

C'4H.,,02N.Fe2Ni (700) (58.25) (4.85) (7.99) (8.37)

Ni(Afaa)2.2Hp (2) Brown 59.42 4.98 7.71 8.20 Diamagnetic

C]6H]x02N4Fe2Ni (59.31) (5.21) (7.68) (8.05)

Co"(Ffaah (3) 667 Blue 62.00 4.60 8.32 8.80 11.81 4.20

C]4H:;oN4Fe2Co (665) violet (61.38) (4.51) (8.42) (8.86)

Co'f Afaa), (4) 700 Violet 63.2 4.81 8.21 8.60 4.10

C]6H]4N4Fe,CO (693) (62.37) (4.90) (8.08) (8.50)

Colll(Ffaa}z(OH)(NH3) (5) 712 Brown 58.02 4.69 10.210 8.56 13.28 Diamagnetic

C]4H]40NSFe2Co (699) (58.40) (4.86) (10.010) (8.43)

Colll(Afaa)2(OH)(NH3) (6) 722 Brown 58.62 5.41 9.46 8.21 Diamagnetic

C"H]XON SFe2Co (729) (59.45) (5.22) (9.63) (8.11 )

Cu(Ffaah (7) 672 Yellow 61.2 4.52 8.26 9.65 1.78

C34H]oN.Fe2Cu (669) Brown (60.96) (4.48) (8.36) (9.49)

Cut.Afaa}, (8) Brown 62.40 4.72 8.21 9.20 1.81

C]6H]4N4Fe2Cu (61.96) (4.87) (8.03) (9.11)

Cu(Afaa}z(NH3)2 (9) 729 Brown 60.12 5.21 11.56 8.82 1.98

C]6H40N6Fe2Cu (731) (59.07) (5.47) (11.48) (8.68)

Ni(Ffap)(CI)(NH3) (10) 412 Yellow 48.92 4.01 6.82 8.81 14.21 5.78 Diamagnetic

C17H17ON2ClFeNi (415) Brown (49.15) (4.09) (6.74) (8.54) (14.14)

Ni(Fap)(OH)(NH3) (11) 388 Brown 51.62 4.61 7.20 14.62 Diamagnetic

CI7H,x02N2FeNi (396) (51.44) (4.53) (7.06) (14.80)

Ni(Afap)(CI)(NH3) (12) Brown 50.41 4.21 6.62 8.41 13.21 Diamagnetic

C,xH,.ON2ClFeNi (50.35) (4.42) (6.52) (8.26) (13.68)

Colll(Ffap),(OH)(NHJ (13) 708 Deep 57.29 4.46 5.82 8.61 14.2 Diamagnetic

C34H3203N3Fe2Co (700) Brown (58.23) (4.56) (5.99) (8.41)

Co(Ffap)(Cl)(NH]) (14) 417 Bluish 50.21 4.20 6.42 8.68 14.24 12.12 4.20

C,7H,70N2ClFeCo (415) Yellow (49.13) (4.09) (6.74) (8.53) (14.19)

Cu(FfapXOH)(NH3) (15) Brown 50.10 4.38 6.68 15.62 1.79

C 17H'S02N 2FeCu (50.82) (4.48) (6.97) (15.83)

Ni(FfabaXCl)(NH3) (16) Red 49.02 3.86 6.42 8.21 13.02 Diamagnetic

C,sH'702NzCIFeNi (48.76) (3.83) (6.32) (8.00) (13.24)

Ni(AfabaXCl)(NH3) (17) Red 48.82 4.20 6.31 7.89 12.64 5.10 Diamagnetic

C'9H'90zCINzFeNi (49.89) (4.15) (6.12) (7.75) (12.84)

Cu(Ffaba)(ClXNH3) (18) 450 Dark 48.42 3.92 6.10 8.20 14.20 1.81

C,sH17OzNzClFeCu (448) Brown (48.23) (3.79) (6.25) (7.91) (14.18)

DEY et 01.: Cu, Co & Ni COMPLEXES WITH FERROCENYL SCHIFF BASES 911

EtOHQntbO

EtOtt-----••• tatt •••.NH40H (aq.)

A. H/CH.X. NH/O

R

~~=H

F. HX)§lcb

A: H/CH.X·O/COO

EtOHNH.OH (aq) ••M.tal~lt

solution

•

R--HM __ Ni

Compln NO. (1)

SCHEMEl

~=f<x t?@j \/ Fe

I. ~,L' .Lo xrd'=~~m

R-H CH. ·CH. HM-CO Co Cu oraX-/III NH NH 0L,-OtI 0tI /III. OH

ConIpIe. NO. U) (6) (!) (I)- -5CtfEME 2

IV

R--H H C1f3 H HM._Ni Ni " Co Cux_O 0 0 0 0Lc-CI OIl Cl Cl OIl

Com~... 119) (!!) (!2) (~) (~)

the compounds (measured by Rast's method) arealso in good agreement with these formulations.Both the ligands HAfaa and HAfaba are solublein CHCl3 and DMSO, while the complexes aresoluble in coordinating solvents and also in com-mon organic solvents.

The molar conductance values (Table 1) of thecomplexes measured in DMSO and DMF suggesttheir nonelectrolytic nature", It has also been ob-served that on prolong standing at room tempera-ture, the AM values in DMSO solutions of (5),(6), (I 0 )-(15) increased showing the presence of1:1 electrolytes in solutions. These results may berationalized by assuming the foUowing equilibriain solutions:

[M(LMXXNH3)]+DMSO ~[M{Lh(DMSOXNH3W +X-

H CH. HNi Hi Cucoo coo coocr Cl CI(ll) (~) (!!)

5ClfEME)

[M{L)I(X)(NH3)] +DMSO ~[M{L) (DMSOXNH3)]+ + X-

(where M = Cobalt{lll) or cobalt{II), nickelrll),copper{ll); L= monobasic bidentate ferrocenylSchiff base; and X = OH - or CI- )

!he nickel{ll) complexes are diamagnetic indicat-109 square planar geometry around nickel{Il) ion".The diamagnetic cobalt{lll) complexes are octahe-dral (may be distorted). On the other hand co-balt{ll) complexes (3), (4) and (14) show magneticmoments in the range 4.1-4.2 B.M. at room tem-perature. The values suggested tetrahedral ar-rangement of donor atoms around central co-balt(ll) ion'". The copper(ll) complexes, Cu(Ffaah,(7), Cu{Afaa}z, (8), CU{Ffap) (OH) (NH3) (IS) and-Cu{Ffaba) (Cl) (NH3), (18) exhibit, magnetic mo-

912 INDIAN J CHEM, SEe. A, OCTOBER 1994

ment values in the range 1.78 to 1.81 BM, the va-lues quite close to the spin only value viz., 1.73B.M. expected for S = 112 system. These valuestentatively suggest a square planar structure forthe copper(II) complexes-':".

The brown copper(II) complex, Cui.Afaa),(NH3h, (9) has an effective magnetic moment va-lue of 1.98 B.M. at room temperature suggestingits pseudo-octahedral structure"!",

The contention that the present diamagneticnickel(II) complexes are square planar is suppor-ted by the appearance of spectral bands measuredin nujol mull at 700-680 nm and 440-420 nm re-gions assignable to IA1g -+ IA2g and IA1g -+ IBIg

transitions respectively in a square planar fieldaround nickel(II) ion". The tetrahedral structurefor the present cobalt(II) complexes (3), (4) and(14) have been further supported by the visiblespectra in the range 700-650 nm assignable to4A2 -+ 4 ~ (P) transition in a pseudo-tetrahedralgeometry!", The other cobalt complexes (5), (6)and (13) are diamagnetic and therefore lead tocobaJt(III) species. These complexes show bandsin the regions 600-580 nm and 460-410 nm as-signable to IA1g -+ I~g and IA1g -+ ITzg transitionsin an octahedral environment". The copper(II)complexes (7), (8), (15) and (18) may attainsquare planar structure as inferred above frommagnetic moment values. The elctronic spectraldata also support this cannotation. The nujol mullspectra are quite different from the tetrahedralelectronic spectral pattern generally observed fortetrahedral copper(II) complexes. The band ob-served at 19,800 ern - 1 may be taken as a prooffor square planar structure for these copper(ll)complexes". The other copper(II) complexes (9)showed bands (nujol mull) at 17,000 cm-I and12,000 em -I (sh) suggesting either a square plan-ar or distorted octahedral geometry.

The infrared spectra of the metal complexeswere recorded in KBr phase and important bandsalong with their tentative assignments have beendiscussed.

Both the Iigands HFfaa and HAfaba showstrong bands in the region 1650-1600 em -I as-signable to C = N stretching. These bands werelowered by 10-15 em -I in the complexes, suggest-ing the coordination of azomethine nitrogen at-om!", The infrared spectrum of the ligand HFfaashows absorption bands at 3490 em -I and 3385em - I, which may be assigned to vasym(NH)andvsym(NH)respectively.

The bending (NH) vibration may be at - 1640-1600 em -I, which is difficult to assign due to thepresence of 'C = N' chromophore and aromatic

ring. However, «NH) frequencies are loweredconsiderably in the spectra in this region. In fact,very broad bands in the region 3400-3300 em - 1

were found in the complexes. This may be due tothe conversion of NH2 to NH - and simultaneouscoordination with the metal ions2o,21. However,this is entirely tentative propositions.

The ligand HAfaba show a band at 1710 cm-Ifor asymmetric stretching of free carboxylicgroup". The complexes of the ligands HFfaba andHAfaba exhibit bands in the region 1600-1570em - I, which may be attributed to the bonded car-boxylate group'", although the presence of 'C = N'chromophore might complicate this interpretation.

The phenolic 'C - 0' stretching vibrations anshifted in the complexes (10 )-(15) to higher fre-quencies by about 10 ± 5 em - I in relation to thefree ligands [« C - 0) in the free ligand observed],at 1520 em -1, suggesting the coordination ofphenolic 'C - 0' to nickel(II), cobalt(II), cobalt(III)and copper(II) ionsI6,18. The OH stretching fre-quencies characteristic of the free ligands do notappear in the infrared spectra of the complexes(10)-( 15).

Bands in the region 560-440 cm - 1 can be as-signed to «M - N) stretching modes'? for thecomplexes (1)-(9). A band in the region 340-330em -I may be assigned to «M - Cl) stretchingmode!". The formation of 'M - 0' band in thecomplexes is supported by the appearance 01bands in the region 500-380 em - I, assignable to«M - 0) modes 19-24.

Both the ligands and the complexes showedcharacteristic bands for ferrocenyl moietyl9,22 at- 3100-3000 em -1, 1440-1400 em -1, 1110-1100cm-I, 880-840 cm-I and 510-490 cm "! respect-ively.

The hydroxy complexes (5), (6), (11), (13) and(15) exhibit bands at 1100-955 cm-I due to«M - OH) along with the bands at - 300 ern - 1

for «M - 0). Only the nickel(II) complexes (1)and (2) have shown broad bands above 3400em - I, which may be assigned to «OH) for latticewater".

The structural formulations of the compoundsare tentatively proposed (Scheme 1- 3) and are orthe basis of their analytical and spectral data.

AcknowledgementOne of us (KKN) is thankful to the CSIR, New

Delhi, for the award of a senior research fellow-ship. We are also thankful to the RSIC, CDRI,Lucknow for elemental analyses and spectral data.

DEY et al: Cu, Co & Ni COMPLEXES WIm FERROCENYL SCHIFF BASES 913

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