Indian Journal of ChemistryVol. 35A, September 1996, pp. 766-770

Synthesis and spectral analysis of nickel(II), copper(II), lead(II), zinc(II), bar-ium(II) and strontium(II) complexes of macrocyclic binucleating ligand

3-formyl 2-hydroxybenzophenone

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

Received 23 May 1995; revised 12 April 1996

Fridel Crafts acylation of benzene with N, N'<ethylenebis r(3-cWorocarbonyl) salicylideneiminato)]nickel(lI), [Niiscnlksalen] followed by hydrolysis afforded 13-formyl-2-hydroxybenzophenone,Hbzphfsa, a new derivative of 3-formylsalicylic acid, 3-fsa.The reactions of Hbzphfsa with ethylene-diamine, 1, 3-diaminopropane or 1, 3-diarninopropane-2-o1 in the presence of Ni(II), Cu(II), Zn(II),Pb(II), Ba(II) and Sr(II) ions afforded new metal complexes of macrocyclic binucleating ligands. Theproducts have been characterised by elemental analysis and spectroscopic (UV/vis, IR, PMR) data.

Much attention has been focused on the synthesisof compartmental ligands capable of bringing twoor more metal atoms into close proximityl-'. Thecompartmental ligands lead to the formation ofbi- and polymetallic complexes, which might haveprofound catalytic activity':", Our earlier work="and work of others 7-11 on the metallic complexesof 3-formylsalicylic acid and its Schiff bases withmono-, di- and polyamines lead us to the realisa-tion that each of the ligand, could in principle,form complexes with either two identical metal at-oms (homo-dinuclear) or two different metal at-oms (hetero-dinuclear). Synthesis of organic corn-pounds through complex mediated reactions in-volving above mentioned ligands have also beenreported by us recently". In continuation of ourwork, we have studied the complexation reactionsof 3-formyl 2-hydroxybenzophonone, Hbzphfsa,with ethylenediamine, 1, 3-diaminopropane or 1,3-diaminopropane-2-01 in the presence of differ-ent metal salts that lead to the isolation of new/novel metal complexes of macrocyclic binucleat-ing ligands. This paper reports the results of thisinvestigation.

Materials and MethodsThe solvents and reagents were purified and

dried by standard procedure':', IR spectra wererecorded in KBr disc, Nujol and HCB mulls.Electronic spectra were taken as Nujol mull usingParkin-Elmer-1330 spectrophotometer. Conduct-ance data were also recorded in DMSO solutionusing Elico-conductivity bridge.

Preparation of the ligandTne method of isolation of the ligand, 3-formyl-

2-hydroxybenzophenone from N, Nvethylenebis[(3-carboxy )salicylideneiminato)] nickel(II),Ni(Hzfsaen) has been reported earlier by usl2

. Thecomplex, Ni(Hzfsaen) on treatment with freshlydistilled S.oClz in dry benzene for 20 h followedby acid hydrolysis afforded 3-formyl 2-hydroxy-benzophenone, Hbzphfsa, m.p. 104°C.

Reactions of3-formyI2- hydroxybenzophenonewith ethylenediamine and Zn( CH3 COOlz2Hz 0

3-FormyJ 2-hydroxybenzophenone (2.26 g, 0.01mol) and ethylenediamine (0.60 g, 0.01 mol) weretaken in methanol (60 ml) and heated undergentle reflux for 2 h. To this mixture was thenadded dropwise, a solution "IfZn(CH3C00lz2HzO(2.19 g, 0.01 mol) in methanol (40 ml). The re-sulting solution was then refluxed for 1 handcooled to room temperature. On reducing the vo-lume to 30 ml and standing at room temperatureyielded light brown solid,[(bzphfsaenz)Znz( CH3COO )z] H20, (1). It was fil-tered, washed with methanol-ether (50:50, v/v)mixture and dried in vacuo. Yield 60% (2.30 g).

With ethylenediamine and Pb(SCN)zSimilarly, the reaction of 3-formyl-2-hydroxy-

benzophenone (2.26 g, 0.01 mol) and ethylenedia-mine (0.60 g, 0.01 mol) in the presence ofPb(SCNlz (3.23 g, 0.01 mol) in methanol-ethanolmixture (60 ml) afforded a yellow product[(bzphfsaenz)Pb2(SCN)z]2HzO, (2). Yield 40%(2.00 g).

DEY et al: COMPLEXES OF 3-FORMYL 2-HYDROXYBENZOPHENONE 767

With 1, 3-diaminopropane and CuCh.2H20A solution of 3-formyl 2-hydroxybenzophenone

(2.26 g, 0.01 mol) in minimum volume of boilingmethanol was added to the pale blue suspensionformed by mixing 1, 3-diaminopropane (0.75 g,0.01 mol) with a saturated solution ofCuCI2.2H20 (1.55 g, 0.01 mol) in methanol. Themixture was heated under reflux for 4 h whereup-on the initial pale blue solid first turned green andthen eventually got dissolved. Methanol was re-moved by boiling on water bath until precipitationhad just commenced. The dark green solid com-pound was filtered, washed with methanol-watermixture (50:50, v/v) and dried over anhydrousCaCl2 at room temperature to obtain[(bzphfsapn2) Cu2CI2]2H20 (3) as green solid.Yield 75% (2.85 g). On drying at· 70-80°C in vac-uo over P40lO yielded [(bzphfsapn2)Cu2CI2] H20(4) as a light green powder. Prolonged heating invacuo at 140-160°C was required for removal ofthe final molecule of water to get[(bzphfsapn2)Cu2CI2] (5).

With 1,'s-diaminopropane and NiCh.6H2 0The mixture of nickel chloride hexahydrate

(1.18 g, 0.005 mol), 1, 3-diaminopropane (0.37 g,0.005 mol) and 3-formyl 2-hydroxybenzophenone(1.13 g, 0.005 mol) was heated under reflux inmethanol (60 mI) for 16 h. The dirty green solidformed was filtered and recrystallized from meth-anol-water (30:70, v/v) mixture to get green com-pound [(bzphfsapn2)Ni2CI2]2H20 (6) in 65% yield(1.20 g) which was dried at room temperatureover CaCI2 (fused).

With 1, 's-diaminopropane and ZnCh. in the pres-ence oJZn( CH3COOh2H20

Zinc chloride (1.36g, 0.01 mol) and zinc acetatedihydrate (0.2 g, 0.001 mol) were dissolved inmethanol (60 mI) and filtered. To the solution, 1,3-diaminopropane (0.75 g, 0.01 mol) in 20 mImethanol was added followed by a solution of3-formyl 2-hydroxybenzophenone (2.26 g, 0.01mol) in methanol (70 mI). The mixture was stirredat room temperature for 3 h whereby a yellowprecipitate was separated out. It was filtered,washed with methanol and dried in vacuo to get[(bzphfsapn2)Zn2CI2]2H20 (7). Yield 70% (2.68g).

With 1, 's-diaminopropane-l-ot and Ba( ClOJ2Barium perchlorate (0.336 g, 1 mmol), 1, 3-di-

minopropane-z-ol (0.18g, 2 mmol) and 3-formylhydroxybenzophenone (0.452g, 2 mmol) were

dissolved in methanol (150 mI) and stirred atroom temperature for 48 h. On reducing the vo-lume to 100 mI and on keeping, a yellow solidcompound [(H4bzphfsapn201)Ba(CI04h] (8) wasobtained, which was collected, washed with etherand dried in vacuo. Yield 50% (0.450 g).

With 1, 3-diaminopropane-2-o1 and Sr{Cl04lzStrontium perchlorate (0.286g, 1 mmol) and

3-formyl 2-hydroxy-benzophenone (0.226 g, 1mmol) were dissolved in ethanol (50 mI) andstirred with 1, 3-diarninopropane-2-01 (0.09 g, 1mmol) at room temperature for 30 h. On reduc-ing the volume and keeping, a yellow compound[(H2bzphfsapn20l)Sr2](CI04).EtOH (9) was ~b-tained. The compound was collected, washed WIthethanol and dried in vacuo. Yield 40% (0.390g).

Results and DiscussionThe in situ reactions of 3-formyl-2-hydroxyben-

zophenone, (Hbzphfsa) with H2NCH2CH2NH2,H2NCH2CH2CH2NH2' and H2NCH2CH(OH)rCH2NH2 in the presence of metalsalts under varied reaction conditions yieldednew metal complexes [(1) to (9)] of new macro-cyclic binucleating ligands (Schemes 1-3). Thecompounds are not well crystalline. All efforts toisolate the metal free macrocycles, Hybzphfsaen.,Hjbzphfsapn, and H4bzphfsapn201 from conden-sation of Hbzphfsa with H2NCH2CH2NH2 orHzN(CH2)3NH2' and or with H2NCH2CH~(OH)CH2NH2,under a. wide variety of conditionsfailed to yield pure products.

HV'c e-, c~I I "=-Io OH 0

InWAcl!2HzO

M.oH; R.flux

J- formyl 2- hydroxybenzopt..non.

+"'2 NHzb., - ~H'

f'b {SCNI,

Scheme-1

H, 0 ~ CUClz2-HzO/M.OH.cre <s : Ofg OH 8 - NiClz6HzO/NeOH

l-formyI2- hydroxybenzopt\enone

+~HJ ~H2CH,-CH,-CH, '-. Zn{OAcli2H,O ••

ZnClz.N.OH

N - Cu Cu Cu Hi Inn_2 I 0 2 2

Compo.nI Cll (~ (ll (!l CZI

Sch••me-2

768 INDIAN J CHEM, SEe. A, SEPTEMBER 1996

The elemental analyses (Table 1) of all the com-plexes (1) to (9), agree with the formulationsshown in Schemes 1-3. Molecular weights andmolar conductance data also support their for-mulations. These results also suggest that the li-gands are binucleating tetrakis Schiff bases asshown in Schemes 1-3. Except for readily explic-able absorptions due to the particular inorganic/organic anion present and except for some fea-tures of the spectrum of [Batl-Lbzphfsapn.ol)(Cl04)2] (8) and [Sr2(H2bzphfsapn201)](Cl04}z.EtOH (9), the infrared spectra of all the corn-plexes (1) to (9) are very similar throughout therange 4000-250 em -I, which strongly suggest thatthe same organic ligand was present in all thecases. Assignment of some of the prominentpeaks are made on the basis of extensive dataavailable for related salicylaldimine cornplexes'v'".Strong evidence that aldehyde and keto groups inHbzphfsa have been completely converted intoSchiff base residue was provided by the disap-pearance of the carbonyl stretching bands at 1680cm-I (-CHO) and 1695.cm-1 (>C=O) and theappearance of a very strong and slightly broadband at 1635 ± 10 cm - I assigned to > C = Nstretch 18. No bands assignable to amine functions(di- and polyarnines used) are present in the com-plexes, suggesting thereby the formation of mac-rocyclic binucleating Schiff bases as discussed

above. All complexes showed broad absorption inthe range 3600-3000 em - I due to OH stretchingvibrations of water or alcohol present in the com-plexes. The spectrum of[(Hbzphfsaen2)Zn2( CH3COO )2]H20 (1) showedbands at 1540 and 1410 em - I ascribable to asym-metric and symmetric stretching modes of acetateanion'? and that of [(bzphfsaen2)Pb2 (NCS)2]2H20(2) showed a band at 2045 cm-I indicative of N-bonded thiocyanate.'? moiety.

The IH NMR spectrum of the dizinc complex,

H ~",I Ph<, c c .

I "H:zC - N OH N - CHz

I 'I /OC'O, IH-C- OH-eO-HO-C- H

I 0,,,/1, 1H':~~~~~ CH,

(~ )

Bo{CIO.)2

M.<JHRoom Temp.

VIH,C c-, c.-o'

II 11_

o OH 03-formyI1- hydroxy

benzophe-none

+NH2 OH NHz, , ,CHz -CH - CHz

\ Sr(CI04h

EtOHRoom TQmp

H yl Ph<, C c-, C/I I

H2C- NON -CH2I \ / \ / I

H- C -OH"-Sr Sr"'HQ- C - H(CI04l2I / \ / \ I EtOH

H,C- ~~O ~-CH2/C C,

Ph : I H

(~)

Scherna- 3

Compound

Table I-Analytical and physical data of the complexes

MoL WI. Found (calcd), %

(Calc.)

C'4HIIl03[(Hbzphfsa)]

235"226"(226)

ZnC36H3407N4 (1)[Zntbzphfsaen.) (OAc)2]H20PblC33H3U04N5S (2)[Pbl(bzphfsaenl)(NCSh12HPCUIClIC3.H1404N. (3)[Cul(bzphfsapnl)(CI)112HPCu,Cl,C3.H3,03N. (4)[Cul(bzphfsapn,)(Clh]HIOCu,Cl,C"H300IN. (5)[Cu,(bzphfsapn,XClhlNi,Cl,C3.H)40.N. (6)[Ni,(bzphfsapn,)(Clh]2HIOZnIClIC3.H3.O.N. (7):Zn,(bzphfsapn2)( CI)2]2HPBa(C3.H3204N.) (CI04h (8)[Ba(H.Bzphfsapn2ol)(CI04h]Srl(C36H3505N4)(CI04h (9)[Sr(H,bzphfsapn1ol)](ClO.h,EtOha Osmometry; b Rast's method; C Mass spectra; d

722b

(759)

762b

(750)

AMohm -'cm'mol-'

C

74,85(74.33)

57.02 4.24(56.48) (4.44)39,80 3,12

(39,34) (2,98)54, II 4,69

(53,68) (4.47)55,24 4.60

(54,98) (4,31)56,95 4,92

(56,35) (4,14)54,98 4.68

(54,37) (4.53)53,91 4.61

(53.42) (4.45)45.82 3.79

(45.52) (3.57)44,61 3.62

(44.21) (3.58)in DMSO;' in water.

H

4.72(4.42)

N M CI

7.81 17.33 1\1\,2"(7:32) (17,10) I 'NO'7.24 42.12

(6.95) (41.17)7,64 16.92 9,14 94,2d

(7.36) (16.72) (9,32) 204<7,08 17,91 10.21 95,0"

(7.54) ( 1712) (9,55) 206e

7.47 17,95 9,58 80,1 d

(7.73) .(17,55) (9,79) 14W7,72 15.02 9,82 95,0"

(7.46 ) (15.64) (9.44) 205"7.82 17,,00 9.11 92, I"

(7.83) (112)

(9,28; 20W6.68 I ,81 7.39

(6.24) (1 .32) (7.91)5.56 18.21 7.12

(5.73) (11.93)( (7,25)

DEY et al: COMPlEXES OF 3-FORMYL 2-HYDROXYBENZOPHENONE 769

[Hbzphfsen2)Zn2(CH3COOh] H20 (1) was re-corded in DMSO-d6 (b ppm) which indicated thedisorete nature of the macrocyclic species in solu-tion : 8.42 (s, 2H, N = CH), 3.85 (s, 8H,NCHzCH2N) and 6.60-8.00 (m, 16H, aromatic).Thus, the presence of approximately co-planarconfiguration of N402 macrocyclic ligands in thecomplexes may be concluded.

The use of Ba(CI04)2 as the templating agent inthe reaction of Hbzphfsa withHzNCHzCH(OH)CH2NHz gave a mononuclearcomplex [(H4bzphfsapnzol)Ba(CI04h] (8). The .in-frared spectrum showed no carbonyl or arrunebands from the precursors but gave two iminebands at - 1640 and 1635 em - I, suggesting thatthere are two environments for these functions.Besides, the vOH is now found at - 3450 cm - 1

as a comparatively sharp band. Two bands at1110 and 1085 em -I are assignable to a unident-ate (C3J perchlorate anion". The binuclear com-plex, [(Hzbzphfsapnzol)Sr2](CI04h.EtOH (9), onthe other hand, gave imine band at 1630 cm - I

and broad bands - 3400 em - I related to OHgroups.The anion give rise to a band at 1100em -I for perchlorate indicating a non-coordinated(Td) anion".

The magnetic properties of the dicopper(ll)complexes [(bzphfsapn2)CuzCI2]2H20 (3),[(bzphfsapn2)Cu2Clz]H20 (4) and[(bzphfsapnz)Cu2CI2] (5) showed that two Cu+2ions, in each of these complexes, are strongly an-tiferromagnetically coupled, (mediated by the en-dogenously bridging phenolic groups) the .magne-tic moments at room temperature (per cation) be-ing 0.72 BM for [(bzphfsapn2)CuzCI2]2H20 (3),0.68 BM for [(bzphfsapn2)CuzCI2]H20 (4) and0.69 BM for [(bzphfsapn2)CuzCI2] (5) respectively.The bridging phenolic vC - ° in the complexes(1) and (2) appeared" at -1580 cm-I. The bin-uclear structure was also confirmed by the reflect-ance spectra in which it was found that the d-dtransition band lies at - 650 nm, which is muchlower than expected for mononuclear copper(ll)complexes of similar ligands-". The temperaturedependence of XM of [(bzphfsapn2)Cu1Clz]2HzO(3 ), is given below:

XM 'and f.A.eff calculated per copper atom in (3).T in OK, f.A.eff = 2.84 JXM.T, where XM was cor-rected for diamagnetism using the diamagneticsusceptibility of (bzphfsapnj)? - from the mea-sured susceptibility of [(bzphfsapn2)Cu2Clz]2HzO(3) and Pascal's constants.

II

The values support a strong antiferromagneticinteraction between two copper atoms.

T 106X~ i1df T lOhX~ Ileft

(BM) (BM)89 2.8 U.0448 220 95.2 0.4110

106 10.1 0.0929 252 122 0.4979120 23.5 0.1508 273 144 0.5630145 44.8 0.2288 290 140 0.5722168 55.2 0.2734 328 179 0.6881195 65.7 0.3214 351 206 0.7636

• cgs units

As six donor atoms (4N and 20) of the dianion-ic macro cyclic ligand (bzphfsapny)? - are coplanar(see previous discussion), and considering a re-port on the structure of bivalent metal complexesof macrocyclic ligands having six donor atoms(4'N' and 2'0')23, one may tentatively propose asquare pyramidal environment (Structure I)around copper(II) in the present complexes.

The magnetic susceptibility of[(bzphfsapn2)Ni1CI2]2H20 (6) was measured atroom temperature only, and the effective magne-tic moment was calculated as 3.18 BM (per Ni at-om). This value suggests a square pyramidalgeometry for the nickel(ll) complex (6) as dis-cussed elsewhere-V".

The electronic spectrum (solid state) of[(bzphfsapnz )Ni2CU2H20 (6) showed bands at465 (sh), 595; 714 and at 1000 nm(sh). Followingthe energy level diagram calculated for nickeltll)in a square pyramidal ligand field?", we suggestthe following assignments of the observed bandfor the complex (6):

Complex 3BI-3Az(P) 3BI_3E(P) 3BI-382 3BI-]A~(F)(6) 465nm(sh) 595nm 714nm 1000nm(sh)

Similar spectral data were reported for nick-el(II) complexes [Nij(5 - CI- salen)NEt2b] (ref.26) and [Ni/OAsMePh2l4 (CI04h] (ref. 24) bothestablished approximately of square pyramidalgeometry.

The molar conductances of .some of the newcompounds in DMSO solution are summarised inTable 1. The A M values (Ohm - I ernZ mol- I) be-tween 80-95 have been observed in DMSO (after

Cl1

Cll

770 INDIAN I CHEM, SEe. A, SEPTEMBER 1996

1 h of dissolution) for the dinuclear complexes (1)& (3) to (7) indicating the presence of 1:2 electro-lytes in the solutions of these complexes?". How-ever, immediately after dissolution in DMSO, AMvalues varies between 15-35 ohm-1 ern? mol-Iindicating non-electrolytic nature. These valuesfor the complexes (1) & (3) to (7) in aqueous so-lution (AM varies between 148-206 Ohm-I ern?mol- 1) suggest them to be normal 1:2 electrolytes.This 1:2 electrolytic nature of the complexes insolution may be rationalized by the followingequation;

[(bzphfsapn2)M2CI2 n(H20)~(bzphfsapn2)M2(S)J2+ + 2CI-

(where S stands for solvent molecule and M =Cu2+/Ni2+ /Zn2+) although the formulations ofthe complexes (1) & (3) to (7 ) suggest their non-electrolytic nature.

Therefore, it is obvious that a dipositive binuc-lear cation is liberated in aqueous solution retain-ing the overall geometry of the molecule except-ing that the epical positions of the chloride ionsare now being taken up by water molecules. Thedifference between the electronic spectra of thenickel(ll) complex (6) in the solid phase and insolution indicates that upon dissolution in water,the average ligand field strength is raised, which isconsistent with the presence of apical chloride li-gand in the solid that is displaced in aqueous so-lution by a water molecule with a stronger ligandfield as discussed above. (Absorption bands at444, 562, 714, 725, 1000 nm(sh) were observedfor (6) in aqueous solution).

Formation of dinuclear lead(ll) complex[(bzphfsaen2)Pb2(NCS)212H20 (2) may be rational-ized in this way".

The introduction of 1, 3-diaminopropan- 2-01 asa lateral unit gives rise to two sets of potentiallydeprotonated hydroxyl groups, i.e., alkoxy and ar-yloxy. The reaction of Hbzphfsa and 1, 3-diamin-opropan-z-ol in the presence of templating agentsBa2+ and Sr2+ gave mononuclear complex[(H2bzphfsapnz0l)Ba(CI04hl (8) and homobinuc-lear complex l(H2bzphfsapn201)Sr21 (Cl04)2.EtOH(9) respectively. 1t may be mentioned that thecrystal structure of Ba(H4L)(CI04h (where H4L= macrocyclic Schiff base ligand derived from2,3-diaminopropane- 2-01 and 2,6-diacetyl-4-methylphenol) has been solved recently". Fol-lowing these results, we may tentatively proposethat in the barium(ll) complex[(H4bzphfsapn201)Ba(004)21 (8), the barium atom

+

is bound to two diametrically opposed N atoms,both phenolic oxygen atoms, and two endogenoushydroxyl groups, and two oxygen atoms from un-identate perchlorate anions (Scheme 3).

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

Delhi for a research associateship. We are alsothankful to the RSIC, CDRI, Lucknow for ele-mental analyses and spectral data.

S

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