Indian Journal of ChemistryVol. 23A, January 1984, pp. 30-32

Complexes of Nickel(II), Cobalt(II}, C.\.ipper(II), Magnesium(II), Zinc(II),Cadmium(ll), Mercury(II), Tin(lV) & Dioxouranium(VI) with 2-Benzoyl-

pyridine Benzoylhydrazone & 2-Benzoylpyridine Salicyloylhydrazone

R L DUTrA· & Md MUNKIR HOSSAINDepartment of Chemistry, University of Burdwan, Burdwan 713104

Received 14 April 1983; revised and accepted 15 September 1983

Two new schiff bases, 2-benzoylpyridine benzoylhydrazone (LH) and 2-benzoylpyridine salicyloylhydrazone (L'H 2)havebeen prepared by condensing 2-benzoylpyridine and benzoylhydrazine or salicyloylhydrazine. Complexes of the types[Ni(L)2]' [Ni(L'HhJ. [Co(LH)CI2], [CU(L)Cl], [Cu(L'H)CI], [Mg(L'H)2], [Zn(L)J, [Zn(L'H),], [Cd(Lh], [Cd(L'Hh],[Hg(Lh], [Hg(L'H}z], [Sn(L)I2]1, [UO,(LXCH3COO)] and [UOiL'H)2] have been prepared and characterised. Thecomplexes are sparingly soluble in water and common organic solvents. In nitromethane the tin(lV) complex alone behaves asa 1:1electrolyte while the other complexes behave as nonelectrolytes. The schiff base ligand LH acts as a neutral NNO donor inthe co! ",:(11) complex while in all the other complexes the two ligands act as monobasic tridentate N NO donors. The probablestructures of the complexes have been deduced on the basis of their analytical, conductance, infrared and electronic spectraland magnetic moment data.

In continuation of our work on complexes ofhydrazone schiff bases, we herein report the synthesisof two new ligands, 2-benzoylpyridine benzoyl-hydrazone (LH) and 2-benzoylpyridine salicyloyl-hydrazone (L'H:J via reaction of 2-benzoylpyridinewith benzoylhydrazine or salicyloylhydrazine.Complexes of these ligands with nickel(II), cobalt(lI),copper(II), magnesiurn(II), zinc(II), cadmium(JI),mercury(II), tin(lY) and dioxouraniumrvl) have beenprepared and characterised.

Materials and MethodsBenzoylhydrazine, salicyloylhydrazine and tin(lY)

iodide were prepared following standardprocedures 1 -3.

Synthesis of the ligands2-Benzoylpyridine (0.001 mol) and benzoyl-

hydrazine (0.001 mol) were taken in 10 ml ethanol andrefluxed for 6 hr on a steam-bath. On cooling,colourless crystals separated, which were recrystallisedfrom hot ethanol (m.p. 150°C) [Found: C, 76.5; H, 5.5;N, 13.9. Calc. for CI9HISN30: C, 75.7; H, 4.9; N,13.9%]. A similar reaction between 2-benzoylpyridineand salicyloylhydrazine gave crystals after refluxing

30

for 2 hr. This compound was also purified fromethanol (m.p. 203°C) [Found: C, 72.0; H, 5.0; N, 13.0.Calc. for C19HlSN302: C, 71.9; H, 4.7; N, 13.2/;,,].

Synthesis of complexesA solution ofNiCl2 .6H20, ceci, .6H20 or cecr;

2H20 (0.001 mol in IOml water for the first and in 5-IOml ethanol for the other two) and a solution of theappropriate ligand [0.002 mol for nickel(II) complexand 0.001 mol for others] in ethanol (10-20 ml) weremixed and refluxed for 1hr. The precipitate soobtained was filtered, washed with ethanol, dried at120De and stored over silica gel.

Similar procedure was adopted for the preparationof nontransition metal complexes using appropriatemetal(II) acetates. Synthesis of [Sn(L)Iz]1 involvedreactionbetween the ligand LH and Snl; in ethanol.Dioxouranium(VI) complexes were obtained usingsolution of uranyl acetate and the appropriate ligandin ethanol. All the complexes were obtained in goodyields.

The formulae, colours, characterisation data andmagnetic moments of the complexes are shown inTable 1. The methods adopted for the analyses ofdifferent metal ions, chloride ion, carbon, hydrogenand nitrogen have been described in our previouspaper+". The techniques of measuring electronic andinfrared spectra, magnetic susceptibility and con-ductivity have also been reported earlier.

Results and DiscussionThe ligand 2-benzoylpyridine is known to give a

ketoxime" which has been used as an analyticalreagent. This ketoxime has also been used to stabilise

DUTTA & HOSSAIN: COMPLEXES OF SCHIFF BASES

Compound

Table I-Characterisation Data of the ComplexesColour Found (Calc.). ""

Reddish-violet[Ni(L'H),]

M

8A(85)15.5

(15.3)8.5

(8.7)9.5

(9.3)15.0

( 15.1)24.8

(24.6)26.3

(26.0)8.8

(R9)1:1.4

( 13.6)15.8

(15.9)9.9

(9;8)\).9

(15.7)25.1

(~5.()

150( 14X)31'.0OH)

[Cu(L'HlCl] Green

[Mg(L'H),]

[In(L'H),]

Yellow

Yellow

[Cd(L'H),] Yellow

[Hg(L'H),] Yellow

Yellow

[Ni(L),] Reddish-violet

[Cot LHlCl,] Green

[Cu(LlCl] Green

[In(L),] Yellow

[Cd(L),] Yellow

[Hg(Ll,J Yellow

[Sn(L)I,]I Red

[UOJLlCH,COO] Yellow

--_._--_._ •.._._._ ....__ .- _._--

nickel(llI) state 7. These facts prompted us to study thereaction of 2-benzoylpyridine with benzoylhydrazineand salicyloylhydrazine, and the studies led tosuccessful synthesis of the Iigands LHII) and L'H2 (II)The IR bands at 1675 and 1580 ern I in the spectrumof LH and the bands at 1645 and 1595 em I in thespectrum of L'H2 are assigned to I'C=O and I'C= N respectively" \ NH appears at 3060cm -I for bothLH and L'H 2' But rOH expected for L.'H, is notproperly resolved due possibly to intramolecularhydrogen bonding. Interestingly an X-ray studx t of[Ni(L'H)J also confirms hydrogen bonding of thephenolic OH group. The pyridine ring vibrations andphenyl ring vibrations expectedly overlap. making itdifficult to identify the bands due to pyridine ring.

S(I'I1('IIII'('S o/[Ni(/.)J. LNi(L HU. [('(JolnC/ ..r CII(L)C/] and [CII(1. IIlC/]

The complexes were either too insoluble in DM F toallow measurement of conductance (c.g. [Nil l.) ,]) orgave very low molar conductance values (c.g.[Ni(L'H)J. -0: [Co(LHlCI,J. 30.0: [Cu(l.)CI] and

tSeth S & Chakraborty S. Department of Phvsic-. Unrvcrsitv ofBurdwan (personal communication).

N

12.1(12.1)10.0

(10.1)13.0

(12.8)12.1

(12.0)IIA

(11.2)10.1

(102)9.1

(9.3)12.5

(127)9.9

(9.7)10.7

(10.5)12.8

(12.6)11.9

(11.7)10.5

(105)5.3

(5.2)

7.0(6.7)

C H CI Ilefr

66.1 4.2 3.1(66.0) (4.0)56.0 3.3 8.8 2.0

(54.9) (3.3) (8.5)69.5 4.6

(69.5) (4.2)65.1 4.365.3) (4.0)

50.1 3.5(505) (3.1)69.5 4.6 3.1

(69.2) (4.2)51.8 3.8 16A 4.7

(52.9) OA) (16A)8.8 2.0

(8.9)

28.5(2X.5)

40.7(40.1)

2.4(17).1.0

e.7)

[Cu(L'HKI] 2.0 ohm -I crn ' mol I). The nickel(II)complexes and copper( IJ) complexes exhibited sharpintense bands at 1590([Ni(LU), 15R5([Ni(LH)2])and1595 ern I ([Cu(l)CI]1 indicating the skeleton 9 > C= N - N = C <. In these complexes the ligandsfunction as tridentate monobasic (NNO) donorscoordinating through pyridine nitrogen. azomethinenitrogen and enolic oxygen. However. in the case of[Cu(LH)CI] there is a strong sharp shoulder at 1620cm I \vhich is considered to be due to lowering of vC= O. Another sharp band at 1580 em I (rC = N)indicates that L'H ~ is coordinated to coppen ll) as amonobasic (NNOI donor in its keto form. Forelectroneutrality the phenolic OH undergoes depro-tonation. In[Co(LHlCIJ a strong band at 1620cm I

indicates coordination through keto oxygen. theligand behaving as a neutral tridentate (NNO) donor.For this complex a far IR hand at 200 ern 1 indicates atrans CI - en - CI attachment I". In the far IR spectraof[Cu(l)C1]. hands at 255 and 280 cml are indicativeof I'Cu·· CI modes of polymeric chloro bridgedoctahedral complexes 1 1

The magneuc moments of the nickelt II) complexesare normal!,II.!1 = 3.1 B.M.j for octahedral stereochern-

31

INDIAN J. CHEM., VOL. 23A, JANUARY 1984

istry. The electronic spectrum of [Ni(L}zJ in nujolshows bands at 12.1kK and 12.3kK which may beassigned as VI eA2K~3T J, and V3 eA2K~3T,iP»respectively. These data give the following values ofspectral parameters: Dq = 1200 em -I, B' = 786em -I

and {3=0.7512. [Ni(L'H}ZJ gives in DMF two bands at11.3kK and 26.3 kK which yield Dq = 1130 em -I, B'=849 em -I and {3=0.81. Pseudo-octahedralstereochemistry is thus indicated. A preliminary X-raystudy (as mentioned earlier) of this compound alsocorroborates a pseudo-octahedral [Ni(NNO}ZJgeometry, with two pyridine rings approximately cis toeach other.

The only cobalt complex, [Co(LH)CI2J, gives amagnetic moment of 4.7 B.M. and three bands in thenujol mull spectrum: at 8.3 kK, VI (4T'g _.4 T2J at16.6kK; V2 (4Tlg~4A2S>; and a charge-transfer band at30.7 kK. The ratio V2/V1 being 2.0, it is a good evidencefor pseudo-octahedral geometry 12. A ligand oxo-bridged dimer with chloro-groups at trans positionsappears to be consistent with all the data.

The copper(II) complexes show magnetic momentvalues of2.0 B.M. and typical broad electronic spectralbands centred around 14.2 and 25.0kK. Both theseproperties are consistent with the presence of distortedsix coordinate copper(II) species13.On the basis of allthe available evidence, the complexes may be assignedpolymeric chlorobridged octahedral structures. Astudy of models of [Cu(L'H)CIJ indicates that it is notpossible to have (OON) coordination of the ligandL'H2 in its keto form. It may so behave only in the enolform, but the enol form is not supported by infraredevidence.

[Mg(L' H)zJ, [Zn(L)ZJ, [Zn(L' H)zJ, [Ct(L)ZJ,[Cd,L'H)ZJ, [Hg(L)zJ and [Hg(L'H)zJ

The infrared spectra of these complexes arecomparable to those of [Ni(L)zJ and [Ni(L'H)zJcomplexes, almost band for band (±5cm -I). In viewof such similarity in the infrared spectra, thesecomplexes are also considered to be pseudo-octahedralwith the ligands functioning as tridentate monobasicNNO donors.

[Sn(L)J1JJThis complex gives a molar conductance value of 78

ohm -I cm2 mol -I in nitromethane (assuming amonomeric formula). No appreciable solvolysis occursin DMF as is indicated by its A M value (74 ohm -I em 2

32

mol :"), The infrared band present at 1590em -I in the. /'complex is assigned to the skeleton >C = N - N = C........,.Far IR gives a strong band at 192 em -I, which isabsent in the ligand. A trans di-iodo ligand bridgeddimeric structure is suggested 14 for this complex.

[UOiL)(CH3COO)] and [UOz{L'HhJReactions of uranyl acetate with ligands LH and

L'H 2 in the ratio 1:2 provide two complexes of verydifferent compositions. The infrared spectrum of[UOz{L)(CH 3COO)J shows bands at 1590 cm-I(assigned to the skeleton )C = N - N =C <) and at1540 and 1430 em -) assigned to Vas COO and VS COOmodes. The difference (110 em -I) of the two modesstrongly favours the presence of bidentate acetatogroup!", The vU02 mode appears at 910 em -I. Anoverall seven coordinate structure is thus indicated. Onthe contrary, the infrared spectrum of [UOz{L'H)ZJshows a strong sharp shoulder at 1610em -I followedby another strong band at 1580 em -I (compare[Cu(L'H)ClJ). There are no aceta to bands present. Theasymmetric uranyl (vas0 - U -0) band appears at 905em -I. It appears reasonable to conclude that the schiffbase acts as a tridentate monobasic NNO donor in itsketo form, the phenolic -OH of L'H2 undergoingdeprotonation (rather than deprotonation of theenolised form of the ligand). An eight coordinatestructure is thus indicated ..

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chemistry (McMillan, New York) 1943, 144.2 Kachhawaha M S & Bhattacharya A K, J inorg nucl Chem, 2S

(1963) 361.3 Brandt R L & Kleinberg J, Inorganic synthesis, Vol. 4, edited by J

C Bailar (Jr) (McGraw Hill, New York) 1953, 119.4 Dutta R L & Hossain Md Munkir, Indian J Chem, 21A (1982)

985.5 Dutta R L & Hossain Md Munkir, Indian J Chem, 22A (1983)

201.6 Sen B, Anal Chem, 31 (1959) 881.7 Drago R S & Baucom E I, Inorg Chem, 11 (1972) 2064.8 Cross A 0 & Jones R A, Practical infrared spectroscopy

(Butterworths, London) 1969.9 Sayed L U & Iskander M p, J inorg nucl Chem, 33 (1971) 435.

\0 Robin J H C & Charles S W, Inorg Chem, 4 (1965) 350.II Sonar M H & Murty A S, J inorg nuel Chem, 42 (\980) 815.12 Lever A P B, Inorganic electronic spectroscopy (Elsevier,

Amsterdam) 1968, 333.13 Cotton FA & Wilkinson G. Advanced inorganic chemistry (Wiley

Eastern, New Delhi) 1972. 916.14 Jones (Jr) R W & Fay R C, Inorg Chern, 12 (1973) 2599.15 Marzotto A, lnorg chim Acta, 62 (1982) 183.