Studies on acetylferrocenylnaphthoylhydrazone (and diacyl hydrazone) and its coordination compounds with lead(ii)

Polyhedron Vol. Printed in Great

12, No. Britain

2, pp.

165-170,

1993 0

0277-5387193 $6.00+.00 1993 Pergamon Press Ltd

STUDIES ON ACETYLFERROCENYLNAPHTHOYLHYDRAZONE (AND DIACYL HYDRAZONE) AND ITS COORDINATION COMPOUNDS WITH LEAD(D) ZHANG HONGYUN,* LI FENG, CHEN PEIKUN, CHE DEJI, CHEN DONGLI and ZHANG HONGQUAN Chemistry Department, Zhengzhou University, Zhengzhou 450052, China (Received

10 August 1992 ; accepted 1 October 1992)

Abstract-Acetylferrocenylnaphthoylhydrazone, acetylferrocenyl-3-hydroxyl-2-naphthoylhydrazone, 1,1‘-diacetylferrocenylnaphthoylhydrazone and l,l’-diacetylferrocenyl3-hydroxyl-2-naphthoylhydrazone have been synthesized by the condensation of acetylferrocene or 1,I’-diacetylferrocene with naphthoylhydrazine or 3-hydroxyl-2-naphthoylhydrazine, respectively. Their lead(H) coordination compounds have been prepared and characterized by elemental analyses, IR, ‘H NMR, UV, TG-DTA and molar conductivities. Results show that the ligands coordinate in the enolic form with lead(I1) and the thermostabilities of the coordination compounds are higher than that of the corresponding ligand due to the formation of the chelate ring.

The special structure of ferrocene has attracted wide interest and a series of derivatives have been synthesized. 1-3 Due to the formation of stable coordination compounds with heavy metals ions the aroylhydrazone ligands are promising as specific reagents in analytical and extractive chemistry.4 This type of compound possesses strong biological activity and can inhibit many vital enzymatic reactions catalysed by heavy metals.’ It is reported that the replacement of aromatic groups by the ferrocenyl moiety in penicillin and cephalosporin molecules improves their antibiotic activity.6 In recent years the research on ferrocenylaroylhydrazone and their coordination compounds has become more extensive.7-g In this paper, we report the syntheses of acetylferrocenylnaphthoylhydrazone, acetylferrocenyl-3-hydroxyl-2_naphthoylhydrazone, l,l’diacetylferrocenylnaphthoylhydrazone and l,l’diacetylferrocenyl - 3 - hydroxyl- 2 - naphthoylhydrazone and their coordination compounds with lead(I1). The form in which the ligands coordinate lead(II), the composition and properties of the coordination compounds were elucidated by elemental analyses, IR, ‘H NMR, UV, TG-DTA and molar conductance measurements.

*Author to whom correspondence should be addressed.

EXPERIMENTAL Measurements

UV-vis spectra were recorded on a HITACHI 220A UV spectrophotometer in the 200-500 nm region using a solution in DMF. IR spectra were obtained using KBr discs with a SHIMADZU IR435 spectrophotometer in the 4OOWOO cm- * region. ‘H NMR were measured with an AC-80 NMR spectrophotometer using DMSO as a solvent and TMS as an internal standard. TG-DTA data were measured with a RIGAKU thermal analyser in a nitrogen atmosphere from room temperature to 800°C. Molar conductance values were obtained with a DDS-11 conductometer from Shanghai Second Analytical Equipment Factory, using DMF as a solvent at 20°C. Carbon, hydrogen and nitrogen were measured with a CARLO-ERBA 1106 elemental analyser.

Materials

The ferrocene used was the industrial product from state operated 504 factory after purifying. Acetylferrocene and 1,l ‘-diacetylferrocene were prepared”,” and purified I * by the method described in the literature. Naphthoylhydrazine and

165

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ZHANG HONGYUN et al.

3-hydroxyl-2naphthoylhydrazine have been prepared, respectively, by the condensation of methyl naphthoate and methyl 3-hydroxyl-2-naphthoate with hydrazine hydrate. Acetates and other related reagents were of analytically pure grade.

Naphthoylhydrazine (3.p2 g, 0.02 mol) and acetylferrocene (4.56 g, 0. 2 mol) in anhydrous alcohol were heated unde reflux with stirring at 85°C for 8 h, cooled and ltered. The crude product was recrystallized twi e in anhydrous alcohol to obtain brown-red crys i 1s and dried in vucuo. Yield 80%, m.p. 21 l-212°C.

which separated out on cooling were filtered and washed successively three times with 0.5% HNO,, water and anhydrous alcohol, and dried in vacua. PbL: is a yellow coordination compound, yield 68%, and PbL: is a yellow coordination compound, yield 80%. Synthesis of coordination compound PbL2 (6)

A solution of Pb(02CMe),* 3Hz0 (0.379 g, 1 mmol) in anhydrous alcohol (10 cm3) was added dropwise with stirring to a solution of H2L2 (0.606 g, 1 mmol) in anhydrous alcohol and DMF (1: 3) (30 cm3). Following the operation for PbL:, a yellow coordination compound was obtained. Yield 65%.

Synthesis of ligund H2L2 (2)

H2LZ was synthesized w ‘th a molar ratio of 1: 2 of l,l’-diacetylferrocene a d naphthoylhydrazine in anhydrous alcohol wit the same operation as HL1. The crude product w s dissolved in DMF and filtered. Anhydrous alcoho was added to the filtrate with stirring and then th golden yellow powder 1 was separated. Yield 65%,im.p. 209-210°C. Synthesis of l&and HL3 (3)

A mixture of acetylferrocene and 3-hydroxyl-2naphthoylhydrazine in a molar ratio of 1: 1 was reacted in anhydrous alcohol under reflux using the same operation as HL’. The product was recrystallized with a mixed solvent of anhydrous alcohol and cyclohexane (1: 1) and dried in vucuo, and reddish-orange tryst 1s were obtained. Yield iI 85%, m.p. 187.5-188.5”C. Synthesis of Zigand H2L4 (4)

The reaction mixture of 1,l’-diacetylferrocene and 3-hydroxyl-2-naphth ylhydrazine in a molar ratio of 1: 2 was heated nder reflux with stirring until the precipitate app ared, and continuously refluxed for 5 h, followin the operation used for H2L2. The orange-yellow / recipitate was obtained. Yield 80%. Syntheses of coordination Icompounds PbL: (5) and

PbL: (7) A solution of Pb(O,CMe),* 3H20 (0.379 g, 1 mmol) in anhydrous (10 cm’) was added dropwise to a solution of (0.792 g, 2.02 mmol) or HL3 (0.824 g, 2.02 m anhydrous alcohol (30 cm’). The reaction ixture was heated under reflux with stirring 6 h. The crystals

Synthesis of coordination compound PbL4 (8)

A solution of Pb(O*CMe), - 3H20 (0.190 g, 0.5 mmol) in anhydrous alcohol (15 cm3) and triethyl orthoformate (4 cm’) was added dropwise to a solution of HL4 (0.32 g, 0.5 mmol) in anhydrous alcohol (15 cm3), and triethylamine (0.4 cm3) was added. The reaction mixture was heated under reflux at 85°C for 8 h, then evaporated to remove unreacted triethylamine and a little ethanol, and cooled and filtered. The precipitate was washed three times with hot alcohol and dried in vucuo. An orange-red coordination compound was obtained. Yield 65%. RESULTS

AND DISCUSSION

Elemental analyses and some physical properties

The ligands 1 and 3 are soluble in hot ethyl alcohol, but 2 and 4 are insoluble. They dissolve in strong polar solvents such as DMF and DMSO. Four coordination compounds of lead do not dissolve in common organic solvents such as ethyl alcohol, but are soluble in DMF. The results of the elemental analyses of the ligands and coordination compounds are given in Table 1. The ligands 1 and 3 coordinate to lead(I1) with a molar ratio of 2 : 1, but 2 and 4 coordinate as 1: 1. As the solubility of these lead(H) coordination compounds is less, we attempted to prepare the single crystal, but did not succeed. The polymerization number n of the structural formula of 6 and 8 in Fig. 1 considers chiefly that the coordination between ferrocenyl diaroylhydrazone and metals decreases the steric effect. IR spectra and ‘H NMR spectra

The important IR absorption frequencies of the ligands and lead(I1) coordination compounds are

Acetylferrocenylnaphthoylhydrazone

Table 1. Elemental analyses of the ligands and lead(H) coordination

compounds

Elemental analyses (%)b N C H

Formula

Molecular weight

HL’

396.26

211.5

Brown-red

HzLZ

606.49

209

Orange-red

HL3

412.26

188

Orange-red

H2L4

638.50

256

Orange-yellow

PbL:

997.72

285

Yellow

PbLZS2Hz0

847.72

269

Yellow

PbL;*HzO

1047.74

316

Yellow

PbL4

843.69

266

Orange

M.p.” (“C)

167

with Pb”

Colour

69.5 (69.7) 70.5 (71.3) 66.9 (67.0) 67.4 (67.7) 54.9 (55.4) 50.7 (51.0) 52.2 (52.7) 51.0 (51.2)

n M.p.s of all coordination compounds are their decomposition bCalculated values are given in parentheses.

5.1 (5.1) 5.0 (5.0) 5.4 (4.9) 4.9 (4.7) 3.7 (3.8) 4.3 (3.8) 4.0 (3.8) 3.6 (3.3)

(Z) (Z) (& (:I) (& (Z) (Z)

temperatures.

a3

C=NNHC-R

C=NNBC-R e’

I

&,

C=NNHC-R II -3

lb),

3(b)

0

2(a), 4(b)

r

5(a), 7(b)

600, 8(b)

(b) (a) Fig. 1. Proposed structure for the ligands la, Za, 3b and 4b, and the complexes 5a, 6a, 7b and 8b.

168

ZHANG Table 2. Important

Formula HL’ PbL: H2L2 PbLZ*2Hz0 HL’ PbL;.H,O H2L4 PbL4 Abbreviations

IR absorption

HONGYUN

et al.

frequencies (cm-‘) of the ligands and their lead(I1) coordination compounds

VW---H) v(C=O)

v()2=N-N+)

v(C=N)

-

154O(vs)

1642(vs)

1578(s) -

3290($) -

1613(vs) -

165O(vs) 1631(vs)

3260(s) -

164O(vs) -

1628(vs)

15OO(vs) 1535(vs) 151O(vs) 1542(vs) 1514(vs) 1622(vs) 156O(vs)

3140(s) -

1635(vs) -

3180(s) -

vK--o)

VW-N) 905(w)

1075(m) -

910(m) 910(m)

1040(m) 999(m) -

912(m) 906(m) 905(m) 936(m)

1242(m)

941(m)

: vs = very strong, s = strong, m = medium, w = weak.

listed in Table 2, and ‘H NMR data in Table 3. It is shown in Table 2 that the characteristic absorption frequencies of v(N-H), #&O), v((3=N) and v(N-N) appeared in the 1314&3260, 1613-1642, 15OG1622 and 905-936 cmi- ’ regions, respectively. The results indicate that there is an acylhydrazonyl group in the molecule of all bhe ligands, which exists in the keto form in the soli state.’ The results in Table 3 show that the single peak (5H) of unsubstituted cyclopentadiene and multiple peak (4H) of substituted c lopentadiene appear in the range 4.00-4.74 ppm in” the ‘H NMR spectra of HL’ and HL3. A multiple peak (4H) of substituted cyclopentadiene was obse ed in the range 4.094.97 ppm in the ‘H NM spectra of H2L2 and H2L4. A multiple peak (7H t or 6H) of the naphthene ring appears at 7.52-8.01 ppm, and the single peaks (1H) of N-H were observed in the 10.70-13.88 ppm region in the ‘H N R spectra of the four ligands. A single peak (1Hf of O-H was observed in the region 8.22-8.61 pp in the ‘H NMR spectra of HL3 and H,L4. I3The re“I ults of ‘H NMR further prove that the free ligands Iexist in the keto form.

The IR spectra of the coordination compounds show significant changes as compared with those of the corresponding ligands. The characteristic absorption bands due to v(N-H) and v(C=O) disappeared, but two new absorption bands were observed in the 1578-1650 and 999-1242 cm-’ regions, respectively, which can be attributed to the stretching vibration of conjugate / \c -N-N=C and C-O groups.* The / \ v(C=N) absorption band was shifted to a lower frequency by 25-62 cm- ‘, while the band attributed to v(N--N) was shifted to a higher frequency by 25 cm- ‘. The changes in these frequencies show that the ligands coordinate to lead(I1) to form neutral coordination compounds through the methylenimine group nitrogen atom and amide oxygen negative ion8 and the ligands are present in the enolic form in the corresponding coordination compounds. The coordination compounds PbL’ * 2H20 and PbL4 are insoluble in deuterated DMSO. The proton peak due to the N-H group disappeared in the ‘H NMR spectra of PbL$ and PbL: * H20,

Table 3. ‘H NMR of ligands (ppm) Methyl group

Ferrocenyl group

Naphthenyl group

HL’

2.18 3H(s)

4.00-4.74 5H(s), 4H(m)

7.52-8.00 7H(m)

10.70 lH(s)

HsL2

2.26 3H(s) 2.22 3H(s)

4.09-4.77 4H(m) 4.24-4.71 5H(s), 4H(m)

7.55-7.99 7H(m) 7.35-8.01 6H(m)

2.09 3H(s)

4.494.97 4H(m)

6.69-7.26 6H(m)

10.76 lH(s) 11.34 lH(s) 13.88 lH(s)

Formula

HL’ H:

N-H

O-H

8.61 lH(s) 8.22 lH(s)

Acetylferrocenylnaphthoylhydrazone

which supported the conclusion of the IR spectra above. The characteristic absorption bands of the naphthene ring were observed in the IR spectra of the ligands and coordination compounds at 157& 1595 and 733-742 cm-‘. The characteristic absorption bands observed at 3085, 1442, 1105, 830, 503 and 482 cn- ’ were attributed to the ferrocenyl group as v(C-H), v(C-C), &C-H), 7c(C-H) and @Fe-ring), respectively. 5

b

II

Fig. 2. The TG-DTA diagram of (a) the ligand HzL2 and (b) complex PbL’ - 2H 20.

UV-vis spectra

UV-vis absorption bands of the ligands and lead(I1) coordination compounds are shown in Table 4. It can be seen that there is a shoulder peak in the UV-vis spectra of the ligands and coordination compounds near 270 nm, which was attributed to the B band of cyclopentadiene. There is a weak and broad absorption band at ca 420-422 nm, arising from the transition of the 3d electrons on iron to either the non-bonding or antibonding orbitals of the cyclopentadienyl ring.’ A strong K absorption band (rc -+ rc* transition) appeared in the UV spectra of the ligands at 286-3 14 nm, while that of the coordination compounds is shifted to a longer wavelength by 2-20 nm. The results indicate that the ligands coordinate to lead(I1) in the enol form, respectively, to form a greater conjugated system which decreased the energy of the whole system. Thermal analysis

The results of TG-DTA for the ligand H,L2 and coordination compound PbL2 - 2Hz0 are shown in Fig. 2(a,b). It can be seen that the ligand H2L2 melted at 209°C accompanied by the endothermal effect, then decomposed exothermally at 239°C. A weak endothermal peak appeared at 271°C. The whole weight loss is about 38.3% until 358°C which suggests that two naphthalene rings break away Table 4. UV-vis absorption bands of the ligands and coordination

169

with Pb”

compounds (nm, L,,, DMF)

from the molecule (talc. ca 42%). The weak and broad exothermal peak was observed at 470°C and weight loss was 39% until 800°C which was attibuted to the decomposition of the ferrocenyl and acylhydrazonyl groups (the residue was iron). A weak endothermal peak and two endothermic decomposed peaks appear at 205,269 and 299°C respectively, in Fig. 2(b), PbL** 2H20. The three weight losses cannot be distinguished. It may be that it loses two molecules of water and two naphthalene groups, accompanied by the whole weight loss of ca 35.2% (talc. 34.2%). The two molecules of water lost at 205°C perhaps exist as coordination water. The chelate continues to decompose until 800°C to lose 26.4% of its weight. This suggests that whole coordination compounds decomposed completely and the remaining mixture perhaps is lead, iron and parts of the ferrocenyl group. The decomposition temperature of lead(I1) coordination compounds is higher than that of the corresponding ligand, which suggests that the formation of the stable chelate ring in coordination compounds increased their thermal stable properties. Molar conductance

The molar conductances of the ligands and coordination compounds in DMF are listed in Table Table 5. Molar conductance of the ligands and coordination compounds in DMF (A, 0-l cm’ mol- I), 20°C

Formula

I

k,,, DMF II

III

Formula

HL’ HzL2 HL3 H2L4 PbL; PbL*.2H,O PbL;.HzO PbL4

270sh 270sh 266 270 270sh 266sh 266 270

293 286 306 314 295 294 326 326

434 438 440 440 431 420 440 442

HL’ H,L* HL3 H,L4 PbL; PbL2.2Hz0 PbL3.H,0 PbL“

Concentration (M) 9.34 x 1.80x 7.76 x 9.40 x 1.91 x 1.30 x 1.00 x 2.00 x

10-4 1O-5 lo- 5 10-5 10-4 10-5 10-5 10-5

A (a- ’ cm2 mol- ‘) 6.76 38.40 45.10 46.00 21.20 17.90 27.73 47.00

ZHANG HONGYUN et al.

170

5. The results from Table 5 show that the molar conductances are in the region 6.7647.0 R- ’ cm2 mole1 due to the ligands and coordination cornpounds being weak electrolytes (the reference values for 1: 1 electrolytes have been taken as 65-90 R- ’ cm* mol- ’ in DMF). ’ 4 Thus, it can be deduced that the ligand coordinates to lead(I1) to form a stable neutral coordination compound, accompanied by the release of acetate.

5. S. R. Patil, U. N. Kantank 6. 7. 8. 9. 10.

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