In dian Jo urn al of Chemistry Vo l. 4SA, Junc 2006, pp . 1362-1367 Synthesis and characterisation of aroylhydrazone complexes derived from some piperidin-4-ones A Man imekalai * & B Senthil Sivakumar Departmc nt of Che mi stry, Annamalai Un ive rs it y, Annamala in agar 608002, In dia Emai l: mekam ay l @hotma il. com Received 5 August 2005; revised 27 March 2006 Ni( ll ) and Cu(l l) co mpl exes of th c types rM ( Ll h ](NOJh ' nH zO, [M ( HL 2 )z ](N0 3 h and IM z ( HL 3 )( N0 3 )41 ' nH z O [L I= ris-2.6-d iph enylpiperidin-4-one benzoy lh ydr a7.0 ne (DPBH ), HL2= cis-2,6-dipheny lpi peridin-4-one salicyloyl hy drazone ( DPSH ) a nd HL 3= trrllls-3- mc th yl-cis-2,6-d iph cnylpiperidin-4-one sa li cy loy lhydrazone (MDPSH)] ha ve bee n sy nth esized and charac te ri zed on the ba sis of elementa l, elcctro ni c, IR a nd ES R spectral analyses and also by co ndu cti vity mcasurcme nt s, ma gneti c moment measurements and th ermograv ime tri c ana lyses (TGA /DTA ). The results renect coo rdin at ion of th e li ga nd s th ro ugh >C=O a nd >C=N groups. In bimeta lli c MDPSH co mpl exes coordinati on occurs through phcnolic oxygen and amide nit l"Ogc r. atoms. Thc powder X-ray diffracti on analysis revea ls th at DPBH and DPSH co mpl exes of Ni( ll ) crys talli ze in simpl e c ubi c unit lauice. IPC Code: In !. Cl 8 C07F I/08; C07 rl SI04 Li gands with N- bond s ha ve bee n much studi ed in recent years b eca use of their rela ti onship to the problem of conve rsion of dinitroge n to ammo ni a or hydraz in e l . 2 . Th e interes t in the study of hy dra zo nes ha s been grow ing due to th eir usc in biological systems] ·5 and analy ti ca l chemis trl · 8 . Transition metal comp lexes of aroy lh ydra zo nes have attracted considerab le in terest not o nl y bec ause of th eir potential application in anti tube rc ul ar agents 5 but al so because of th e va ri ous bonding and stereoc he mi cal possibilities that they offer . A survey of lit erat ure shows many reports on aroy lh ydrazone co mplexes derived from aliphatic, aroma ti c and hete roaroma tic b I d ') · 14 . car o ny co mpoun s . How ever , no systematIc work ha s bee n done on co mpl exes derived from saturated heterocy clic ca rbonyl compo unds. Thi s prompted us to undert ake an in vestigation of th e com pl exa ti on tendency of aroy lh ydrazones derived from saturated six-me mb ered heterocyc lic ket one s. We repo rt here the syn thesis and characterisation of three aroy lhy dr azo nes (Scheme I) and their complexes with CuOI) and Ni(ll) ions . Mater ials and Methods Preparation of li gands and comp lexes The li ga nd s DPBH , DPSH and MDPSH wer e p t'e pared as repo rted in lit er ature by react ing benzoyllsa li cylolylhydrazine with a ppropriate heterocyclic keto nes and characte ri sed IS on the basis of NMR spectra l mea s urement s. Dry finely powd ered ligand (5 mmol) [1 .85 g ( DPBH )/1.9 3 g ( DPSH)] wa s added slow ly to a hot methanolic (80 cm}) so luti on of metal( I1 ) sa lt (5 mm o l) [copper(U) nitrate trihydrate (1 .21 g)/ni cke l(ll) nitr ate hexahydrate ( 1.45 g)] w ith stin in g. Th e sol uti on wa s h eated und er reflux for 8- 10 h. Th e green co lo ured com pl exes 1-4 separa ted out were filtered, washed with hot benzene, followed by hot water and dried ove r calcium chloride in a desiccato r. Th e yields were in the range 60-70 %. Th e comple xes decomposed at 240 0 (1), 274 0 (2), 245 0 (3) and 237 0 (4). To a DMF so luti on (20 cm 3 ) of MDPSH (0.2 g, 5 mm o l), a met hano li c so lution (60 cm 3 ) of meta l( ll ) sa lt (5 mmol) [ni cke l( lI ) nitrate hexa h ydrat e N-NHJ-@ 6 · 2 6 Ph N Ph O ." HO 2 6 Ph N Ph H H H L' (DPBH) HL' (DPSH) HL' (MDPSH) L I = cis-2,6-Diphenylpiperidin-4-one benzoyl hy dra-zone (DPBH ) HL z =cis-2,6-D iph enylp iperidin-4-one sal ic y l oy I-hydrazone (DPSH) HL 3 =t rallS- 3-M e th yl-cis-2,6- di ph eny Ipi pe ri di n-4-one salicy loy l- hydrazone (M DPSH) Scheme 1
Transcript
Indian Journal of Chemistry Vo l. 4SA, Junc 2006, pp. 1362- 1367
Synthesis and characterisation of aroylhydrazone complexes derived from some piperidin-4-ones
A Manimekalai * & B Senthil Sivakumar
Departmcnt of Chemi stry, Annamalai Un iversity, Annamala inagar 608002, India Emai l: mekamay l @hotmail. com
Received 5 August 2005; revised 27 March 2006
Ni(ll ) and Cu(l l) co mplexes of thc types rM (Ll h ](NOJh'nH zO, [M(HL2)z](N03h and IM z(HL3)(N03 )41'nH zO [L I= ris-2 .6-d iphenylpiperidin-4-one benzoy lhydra7.0ne (DPBH ), HL2= cis-2,6-diphenylpi peridin-4-one sa licyloy lhydrazone (DPSH ) and HL 3= trrllls-3- mcthyl-cis-2,6-diphcnylpiperidin-4-one salicy loylhydrazone (MDPSH )] have bee n synthesized and charac teri zed on the basis of elementa l, elcctroni c, IR and ES R spectral ana lyses and also by conducti vity mcasurcments, magneti c momen t measurements and thermograv imetri c analyses (TGA/DTA ). The results renect coordinat ion of the li gand s th ro ugh >C=O and >C=N groups. In bimetalli c MDPSH complexes coordination occurs through phcnolic oxygen and amide nit l"Ogcr. atoms. Thc powder X-ray diffraction analysis revea ls that DPBH and DPSH co mplexes of Ni( ll ) crystalli ze in simple cubic unit lauice.
IPC Code: In !. Cl 8 C07F I/08 ; C07rl SI04
Ligands with N- bonds have been much studied in recent years because of their re latio nship to the probl em of conversion of dinitrogen to ammoni a or hydraz ine l
.2
. The interest in the study of hydrazones has been growing due to their usc in biolog ical systems]·5 and analyti cal chemis trl ·8. Transition metal comp lexes of aroy lhydrazones have attracted considerable in terest not only because o f their potenti a l appl ication in anti tubercul ar agents5 but also because of the various bonding and stereoche mi cal poss ibiliti es that they offer. A survey of literature shows many reports on aroy lhyd razone complexes derived from aliphatic, aro matic and he teroaromatic
b I d ') · 14 . car ony compoun s . However, no systematIc work has been done o n complexes derived from saturated heterocyclic carbonyl compounds. Thi s prompted us to undertake an in vestigation of the compl exation tendency of aroy lhydrazones deri ved from saturated six-me mbered heterocyclic ketones. We report here the synthes is and characterisation of three aroy lhydrazones (Scheme I) and their co mplexes with CuOI) and Ni(ll ) ions .
Materials and Methods Preparation of ligands and complexes
The ligands DPBH , DPSH and MDPSH were pt'epared as reported in literature by reacting benzoyllsali cylolylhydrazine with appropriate
heterocyclic ketones and characteri sed IS on the basis of NMR spectral measurements.
Dry finely powdered ligand (5 mmol) [1 .85 g (DPBH )/1.93 g (DPS H)] was added s lowly to a hot meth anolic (80 cm}) soluti on of metal(I1 ) sa lt (5 mmo l) [copper( U) nitrate trihydrate ( 1.21 g)/ni ckel(ll ) nitrate hexahydrate ( 1.45 g)] with stin ing. The sol ution was heated under reflux fo r 8- 10 h. The green coloured complexes 1-4 separated out were filtered, washed with hot benzene, followed by hot water and dri ed over calcium chloride in a desiccator. The y ields were in the range 60-70%. The complexes decomposed at 2400 (1), 2740 (2), 245 0 (3) and
237 0 (4). To a DMF solution (20 cm3
) of MDPSH (0.2 g, 5 mmol), a methano lic soluti on (60 cm3
) of meta l(ll) salt (5 mmol) [nickel(lI) nitrate hexahydrate
N-NHJ-@
6· 2 6
Ph N Ph
N-NHJ~
O. " HO
2 6
Ph N Ph
H H H
L' (DPBH) HL' (DPSH) HL' (MDPSH)
L I = cis-2,6-Diphenylpiperidin-4-one benzoy l hydra-zone (DPBH) HLz=cis-2,6-Diphenylpiperidin-4-one sal icy loy I-hydrazone (DPSH) H L3=t rallS-3-Methyl-cis-2,6-di pheny Ipi peri di n-4-one sal icy loy lhydrazone (M DPSH)
(1.45 g)/copper(Il) nitrate trihydrate (1.21 g)] was added and heated under reflux for 8 h. The pH of the solution was adjusted to 7 using I % alcoholic KOH in the case of nickel(II) complex preparation and then refluxed. The pink coloured Ni(II) complex 5 and green coloured copper(II) complex 6 which separated out, were filtered, washed with hot benzene, followed by hot water and dried over calcium chloride in a desiccator. The yield was 50% (5) and 70% (6) and both the complexes decomposed above 300°C.
Analysis
Elemental analyses were carried out in HERAEUS CARLO ERBA 1108 elemental analyzer and IR spectra of the ligands and their complexes were obtained in KBr pellets on an NICOLET-AVATAR 360 Ff-IR spectrometer. The metal contents were estimated after decomposition of the complexes with concentrated H2S04 as reported 16 . Electronic spectra were recorded in DMF on HITACHI UV-2001 double beam spectrometer while diffuse reflectance spectra were recorded on Varian Cary 5E UV-vis spectrophotometer. The magnetic susceptibility measurements and conductivity studies in DMF were made at room temperature using EG and G 155 vibrating sample magnetometer and electrolytic resistance bridge, respectively. Cyclic voltammetric studies were carried out using a model ECDA-OOl, basic electrochemistry system using glassy carbon working electrode, platinum wire counter electrode and Ag/ AgCI reference electrode at room temperature m deareated DMF usmg tetrabutylammonium perchlorate as supporting electrolyte. Thermal analyses were done on integrated differential analyzer
model STA 1500 PL in an atmosphere of air at a linear heating rate of 20°C/min. Powder X-band electron spin resonance spectra were recorded on Varian EI12 ESR spectrometer. X-ray (powder) diffraction patterns were recorded on a JEOl JDX-8030 X-ray diffractometer using CuKa radiation (A. = 1.54...\).
Results and Discussion The formation of the complexes IS shown m Scheme 2.
, 'v
M= Cu(II) . Ni(lI) Ao '~v
Scheme 2
The analytical data (Table 1) reveal that DPBH and DPSH complexes 1-4 have 1:2 metal to ligand stoichiometries whereas MDPSH complexes 5 and 6 have 2: I stoichiometries. The molar conductivities of DPBH and DPSH complexes indicate 1:2 electrolytes in DMF. These complexes are soluble only in coordinating solvents like DMF and DMSO while MDPSH complexes are insol uble in these solvents.
Electronic spectra of complexes 1-4 were recorded in DMF. Diffuse reflectance spectra were recorded for
Table I-Physical and analytical data of complexes
[Complex] Found (Caled) (%) Am (Qol cm2 mo!" l) !Jerr (BM) (Mo lecular formula) C H N Metal
complexes 5 and 6. The bands observed in the region 275-315 nm and 360-400 nm are attributed to the transitions within the ligand molecules and charge transfer transitions, respectively in all the complexes. The Cu(lT) complexes 2 and 4 show additional bands in the visible region (672 and 603 nm) and these
bands are assigned to d-d transition, i.e. 2 B I -7 2 B2g
transition suggesting square planar geometr/ot.
Broad bands of medium intensity centered around
3450-3000 cm-I in the IR spectra are assigned to VNH
and VOH present in the complexes. The striking feature
(Table 2) is shifting of Vc=o of carbonyl group and VC=N of azomethine group to lower frequencies relative to the free ligands which indicates carbonyl oxygen and azomethine nitrogen coordination 10.
Absence of appreciable change in the frequency corresponding to the bending mode of hydroxyl group (DOH) in DPSH complexes 3 and 4 compared to the free ligand DPSH reveal s that the phenolic OH is not
deprotonated in these complexes. The DOH band for phenolic hydroxyl group observed at 1363 em-I in the free ligand MDPSH moves to higher frequencies in the MDPSH complexes 5 and 6, thus supporting the coordinating nature of phenolic oxygen during complexation lOb . Coordination of amide NH to metal ions 17 in complexes 5 and 6 is supported by the
appearance of sharp bands due to DNH around 1560
cm-I. The appearance of new intense peaks around 1380 and 820 cm-I in complexes 3 and 4 and 1380 and 1000 cm- I in complexes 1 and 2 are attributed to the presence of ionic nitrate in these complexes l 8
. The new peaks around 1330 cm-I are attributed to the monodentate coordinating nature of the nitrate group in complexes 5 and 6 19
. The non-ligand bands due to
VM-O and VM -N vibrations are observed in the 600-500 and 500-400 cm-I regions respectively 10
The observed magnetic moment of copper(II) complex 4 is closer to spin only value and somewhat lower value is observed for coppcr(II) complex 2. Magnetic moments of nickel(lI) complexes 1 and 3 are substantially lower than that of spin only value expected for octahedral and tetrahedral geometries . Besides, the fully paramagnetic octahedral and tetrahedral complexes and fully diamagnetic square planar complexes a number of complexes with the same stoichiometry have been reported to have magnetic values ranging from 0.6 to 2.5 BM at room temperature and show the rare phenomenon of spin state isomerism2o. In the solid state, probably mixed stereochemistries exist, i.e., both the diamagnetic square planar complex ar.d the paramagnetic tetrahedral complex may be present in solid state20-22
in the present study. The magnetic moments of MDPSH complexes 5 and 6 also support square planar geometries for these complexes.
Table 2-IR (cm I) and electronic spectral data of complexes
El ectronic spectra System VM _O VM.N Am", (nm) (log £) NO) VC=N Amide III b OH b N.H
MANIMEKALAI & SENTHIL SIVAKUMAR: Ni(lI ) & Cu( lI ) COMPLEXES OF AROYLHYDRAZONES 1365
The ligands DPBH and DPSH are reduced in a single step during electrochemical reduction and the observed cathodic potentials correspond to the reduction of carbonyl group. The anodic potentials observed at +1.46 Y in DPBH and +0.92 Y in DPSH are attributed to ox idation of am ide NH23 . The Ni(lI) complex 1 undergoes one electron reduction to Ni(l) species in DMF sol ution at - 1.54 y24. However,
i(lI) complex 3 exhibits li gand based reduction at - 1.29 Y. The high anodic potential at +1.57 Y in this complex is probably due to intramolecularly hydrogen bonded phenolic OH group present in the complex. Table 3 reveals that the reduction processes are metal centered reductions in Cu(Tl) complexes. In C u(ll ) complexes, Cu(II) is ox idi zed to C u(lll) ion at the anodic potentials +0.40 (2) and +0.58 Y (4) and this process is fo und to be quasireversible (appearance of peaks at +0.18 and 0.23 Y in the reverse scan)25 . The peak at -0. 13 Y in 2 and at -0.036 Y in 4 correspond to the reduction of Cu(H)-Cu(l) ions25. This process is found to be irreversible in nature. The hi ghly cathodic potentials at - 1.07 (2) and at - 1.18 Y (4) correspond to the reducti on of bound ligand present in the complex .
The Cu(Il ) complex 6 exh ibits isotropic ESR spectrum, i.e. having only one intense broad s ignal with no hyperfine structure. This may be due to dipolar exchange and unresolved hyperfine interaction26
. The giso value suggests the presence of grossly misaligned tetragonal axes . For the other copper(IJ) complexes 2 and 4, anisotropy in 'g' values is observed. The two major components of the g tensor in the axial ly symmetric field (g II and 3.1) are
computed from the spectra. The hyperfine coupling constant (All) was measured directly from the spectra.
Table 3 reveals that g il va lues are greater than 3.1
values which suggest that d/ _ / is commonly the
ground state and the 3d unpaired e lectron of Cu(ll) ion should occupy the d 2 2 orbital26
. Kivelson and x - y
Nieman27 have reported that 311
is moderately sensiti ve
funct ion for indicating covalency. Normally, gil is 2.3
or more for ionic environment and it is less than 2.3 for more covalent env ironment. The present EPR results show that the bond between C u(II) and ligand is covalent in nature.
.. (gil - 2.0023) .. h G factor IS defmed as and IS 111 t e
(g.1 - 2.0023)
range 4.11 to 6.31 for the present complexes. These values indicate that the local tetragonal axes are only sl ightly misaligned and the presence of d/ _ / ground
state. The bonding parameter a 2, measure of the
covalency of the in-plane cr bonds is calculated accordi ng to:
a2=(A/P)+(gll - 2.0023)+3/7(g.1 - 2.0023)+0.04
where P = 0.036 cm-I. The a 2 values for the
complexes fall in the range of 0 .73 indicating apprec iable in-plane covalenc/6
.
The combined TG/DT A diagrams depict two stage decompositions in all the complexes . In stage I, two
[@XCONHNH 2 J molecules of sal icyloy lhydrazine OH are eliminated in DPSH complexes. The observed wei ght loss (34%) is in good agreement with the calculated values (31.9% 3 ; 31.8% 4). In MDPSH complexes, one molecule of nitrate ion and the water molecules
Table 3 --Cyclic voltammetric and ESR spectral data of complexes No. Compound C~c1ic voltammetric data ESR spectral data
Electrochemical Electrochemical All 0 G > gil 0 g,v ex-
No. System Decamp. range Peak temp. Order (n) of £* log A S* (K) (DTA) (K) react ion (J ma r l) (J K·l ma r l)
Ni(II)-DPBH 526 - 618 (Stage I) 548.75 I 25.85 x 104 24.34 2. 16 x 102
6 19 - 780 (Stage II) 737.40 0 8.45 x 104 5 . .50 - 1.47 x 102
2 Cu(II)-DPBH 423 - 603 (Stage I) 503 .90 22.48 x 104 23.24 1.96 x 102
604 - 832 (Stage II) 783.69 1/2 7.47 x 104 4.6 1 - 1.65 x 102
3 Ni(II)- DPSH 535 - 6 19 (Stage I) 548.30 I 7.40 x 104 6.40 - 1.27 x 102
620 - 789 (Stage II) 740.67 1/2 9.64 x 104 6.41 - 1.30 x 102
4 Cu(JI)-DPSH 501 - 62 1 (Stage I) 521.36 1 4.54 x 104 3.76 - 1.78 x 102
622 - 794 (Stage II) 757.28 1/2 11.68 x 104 7.78 - 1.04 x 102
5 Ni(lI)-MDPSH 32 1 - 540 (Stage I) 494.74 0 2.56 x 104 2.29 - 2.05 x 102
541 - 676 (S tage II ) 656.74 1/2 14.12 x 104 I 1.21 - 0.37 x 102
6 Cu(ll)-MDPSH 3 12 - 527 (S tage I) 524.27 0.96 x 104 0 .75 - 2.35 x 102
528 - 634 (Stage II) 573.05 10.77 x 104 9.05 - 0.77 x 102
'Iq
@( !yt 7-- "-~ /
........... M (N03)2'nH2O
/ "~ -QN\~IX§J ~ ~ ()
.y1< X
"h
Complex M X n Complex M n
1 Ni(JJ) H 1 5 Ni(II)
2 Cu(II) H 2 6 Cu(II) 2 3 Ni(JJ) OH 0
4 Cu(II) OH 0
Scheme 3
present in the complex are eliminated in stage I decomposition . The observed mass loss of 14% in Ni(II) and Cu(II) complexes are in agreement with those of calcu lated values(l4.2% 5; 12% 6). In Ni(II) complex 1, one molecule of benzoylhydrazine, two molecules of nitrate and water molecules are eliminated in the step I, with the observed mass loss of 30% (calcd 29.6%). One mo lecul e of ligand and water molecules are elimi nated with the observed mass loss of 40% as against the calculated mass loss of 42 % in Cu(JI ) complex 2. In the second stage, remaining organic matter gets decomposed leaving metal ox ide wi th some residual carbon in all the complexes. The decomposition of complexes was 8.lso
studied using non-isothermal kinetic studies . Thermokinetic parameters (Table 4) were evaluated accordi ng to Coats and Redfern method28
.
The initial decomposition temperature of the TG curves and the peak temperature of DT A curves have been used to compare the thermal stabilities of metal chelates. The stab ilities of Ni(U) complexes are greater than those of Cu(II) complexes.
The X-ray diffraction data of Ni(II) complexes 1 and 3 reveal that these complexes crystall ise in si mple cubic system with lattice constants 20.41 and 23.89 A, respectively . These studies show that the probable structures of the metal complexes can be depicted by Scheme 3.
References I Dilworth J R, Coord Gem Rev. 21 ( 1976) 29. 2 Iskander M F, Zayan S E, Khalifa M A & EI-Sayed L, J
Inorg Nucl Gem. 36 ( 1974) 55 1. 3 Bie l J H, Horita A & Drukker A E, Psycho Pharlllacological
Agel/ts, edited by M Gordon, Vol. I (Academic Press, New York) , 1964.
4 (a) Jhonson R K, Murphy T B, Rose N J, Goodwin W H & Pickart L, II/ org Chilli Acta. 67 (1982) 159; (b) Guillon J, Reynolds R C, Leger J M, Guie M A, Massip S, Dallemagne P & Jarry C, J EI/zyme Inhib Med Chelll, 19 (2004) 489 ; (c) Desai KG & Desai K R, Indian J Chem, 44B (2005) 2097.
5 (a) Buss J L, Kyle E A, Shephard C & Ponka P, Biochem Phannacol. 65 (2003) 349; (b) Deepa K P & Arvindakshan K K, Appl Biochem Biotechl/ol. 118 (2004) 283.
6 (a) Garcia-Vargas M, Gallego M & De la Guardia M, Analyst, lOS ( 1980) 965; (b) Gallego M, Garcia-Vargas M & Valcarcel M, Analyst. 104 (1979) 6 13; (c) Case F H, Schilt A A & Simonzadeh N, AI/al Chelll. 56 (1984) 2860.
7 (a) Srivastava S K, Srivastava B K, Gupta N, Pandey 0 P & Sengupta S K, Indian J Chem. 36A (1997) 778; (b) Patil S S & Sawant A D, Indian J Chelll. 37 A (1998) 1038.
8 Katyal M & Dut Y, Talanta. 22 (1975) lSI. 9 Dutta R L & Munkir Hossain Md, J Sci II/d Res. 44 (1985)
635. 10 (a) Narang K K & Aggarwal A, Illorg Chim Acta. 9
(1974)137; (b) Mohan M, Kumar A, Kumar M & Jha N K, Inorg Chim Acta. 136 (1987) 65.
II Qing-bao S, Gen-rong Q. Tian-hua S, Zhen-ping Y, Yongmin L, Xiao-li W & Yong-xiang M, Syl/th React II/org Met-Org Chell1. 34 (2004) 479.
12 (a) Pandey J K, Pandey 0 P & Sengupta S K, Indian J Chem. 43A (2004) 1906; (b) Sivasankar B N, III dian J Chelll, 44A (2005) 1806.
13 Manzur C, Millan L, Figueroa W, Boys D. Hamon J R & Carrillo D, Organollletallics, 22 (2003) 153.
14 Ali S A, Mohamed H A & Ramadan R M, J Coord Chelll. I (2005).
IS Manimekalai A, Senthil Sivakumar B & Maruthavanan T , II/dian J Chelll. 43B (2004) 1753.
16 Vogel A I, A Text Book of Qual/titative II/organic Analysis. 4th edn (ELBS London), 1978, pp. 747, 379.
17 Aggarwal R C & Rao T R, J Illorg Nucl Chelll. 40 ( 1978) 171.
18 Nakamoto K, Infrared and Ralllall Spectra of II/orgallic al/d Coordinatiol/ Compoul/ds, 3rd edn (Wiley-Interscience Publication, New York), 1978. pp. 244.
