Coordination compounds of hydrazine derivatives with transition metals—III

J. inorg, nucl. ('hem., 197 I, Vol, 33. pp. 435 to 443.

COORDINATION DERIVATIVES

Pergamon Press.

Printed in ( h e a t Britain

COMPOUNDS OF HYDRAZ1NE WITH TRANSITION METALS-Ill*

THE REACTION OF AROYL H Y D R A Z O N E S WITH Ni(ll) and Cu(ll) SALTS L. EL SAYEI) and M. F. I S K A N D E R Chemistry !3epartment, Faculty of Science,/Mexandri:~ L niversity, Fgypt, U .A, R. (Received I ,hmuary 19701

A b s t r a c t - T h e reaction of differently substituted aroyl hydrazones ( R , C H - - N . N H . C O . R ' ) with nickel(ll) and copper(ll) salts were investigated. Magnetic and spectral data showed that in the case of nickel(ll) chloride, octahedral complexes were formed with the ligands reacting in the keto lk)rm whereas in the case of nickel(ll) and copper(l I) acetate square planar complexes were obtained with the ligands coordinating through the enol form. With copper(ll) chloride, reduction took place and mono (aroyl hydrazone) copper(I) monochloride compounds were isolated.

INTRODUCTION ACID hydrazides(I) and their corresponding aroyl hydrazones(ll) were reported to possess tuberculostatic activity [11. Their mode of action was attributed to the formation of stable chelates with transition metals present in the cell. Such process inhibits so many vital enzymatic reactions catalyzed by these transition metal ions[2]. R ' C O ' N H "N H,_,

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(1)

(11)

It seemed desirable to investigate the reaction of aroyl hydrazones with divalent transition metals. Such ligands can coordinate either in the enolic form [3 a] (l l a) or in the keto form [3b] (I l b) \ C

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* Part 11, R. M. lssa, M. F. lskander and M. F. EI-Shazly. Z. anorg, allg, Chem. 354, 98 ( 1967 ). I. Ng. Ph. Buu-Hoi, Ng. D. Xuong, Ng. H. Ham. Fernand Binon and Rend Roger. J. t h e m Soc. 1358 ( 1953); T. S. Ma and T. M. glen, ,4 ntibiotics and Chemotherapy 3.491 (1953). 2. Q. Albert, Nature, Lond. 9, 370 (i953): J. M, Price, Federation Proc. 20, 223 (1961): .I.M. Price, R. R. Brown and F. C. Larson, J. Cline. Invest. XXXYI. 1600 (1957). 3. (a) L. Sacconi, J. Am. chem. Soc. 74, 4503 (1952): H. Ohta, Bull. chem. Soc. Japan 31, 1056 (1958); ibid. 33, 202 (1960). (b) K. Nagano and H. Kinoshitm Chem. phm'm. Bull. Tokyo 12, I 198 (1964). 435

436

L. EL S A Y E D and M. F. I S K A N D E R

N-isopropylidene benzoyl hydrazine and o-hydroxy benzoyl hydrazine were found to react with transition metal ions Cu(II), Ni(II), Co(lI) and Zn(ll) in the keto form. Sacconi[4] showed that the tendency of ligands, of type I I, to react with Ni(II) in the enol form depends on the aromaticity of the R group in the hydrazine residue. In the present work, the reaction of some substituted N-benzylidene aroyl hydrazine with Ni(lI) and Cu(ll) salts are considered. The structure of the complexes isolated were elucidated by recording their visible and i.r. spectra, and measuring the magnetic moments of some characteristic compounds. EXPERIMENTAL

Preparation of the organic ligands Benzoyl and o-hydroxy benzoyl hydrazines were prepared by the method given by Struve[5]. These hydrazides were crystallized from ethanol m.p. 113 ° and 147°C respectively. The aldehyde aroyl hydrazones were prepared by the reaction of aroyl hydrazine (0.1 M) with the corresponding aldehyde (0.1 M) in ethanol.

Preparation of metal complexes (i) Dichloro bis-(N-substituted benzylidene aroyl hydrazine) nickel(ll). A hot solution ofnickel(il) chloride hexahydrate (0,01 M) in absolute ethanol (15 ml) was added dropwise with stirring to a warm solution of the corresponding aldehyde aroyl hydrazone (0-025 M) in ethanol (20 ml). The reaction mixture was heated on a steam bath for 10 rain. The pale green fine crystals which separated out, on cooling, were filtered and washed with absolute ethanol. (ii) Bis-(N-sabstituted benzylidene aroyl hydrazinato) nickel(ll). A solution of aroyl hydrazone (0.025 M) in absolute ethanol (20 ml) was refluxed for 15 min with nickel acetate (0.01 M). The orange fine needles which separated on cooling were crystallized from chloroform. The bis-(N-furfurylidene benzoyl hydrazinato) nickel(l I) complex was prepared in a similar way. (iii) Bis-(N-substituted benzylidene aroyl hydrazinato) copper(ll). The copper(ll) chelates were prepared by the reaction of aroyl hydrazone (0.02 M) with copper acetate (0.01 M) in ethanol (30 ml). The isolated complexes were filtered and washed with hot ethanol several times. (iv) Mono(N-sabstituted benzylidene aroy! hydrazine) copper(l): monochloride. A hot solution of aroyl hydrazone (0.02 M) in ethanol (20 ml) was treated with CnCI2'2H20 (0.01 M) in ethanol (10 ml). The immediately formed yellow crystals were filtered and washed thoroughly with boiling ethanol.

Chemical analysis The elemental analysis (C,H and N) were performed by A. Bernhard Microanalitschen laboratorium Mulheim (Ruhr) Germany. Copper[6a], nickel[6b] and chloride[6d] contents were estimated according to standard methods.

Spectral measurements I.R, spectra were made with a unicum S.P. 200 spectrophotometer. C~dibration was made with polystyrene film. Solid samples were examined as Nujol mull and/or as KBr discs. The electronic spectra were measured with a unicum S.P. 500 or S.P. 800 spectrophotometers. Mull spectra were taken using the method described by Lee et al.[7]

Magnetic measurements Magnetic measurements were done at room temperature by the Gouy method using mercury(lI) tetrathiocyanato cobaltate(11) for calibration. 4. L. Sacconi, J. Am. chem. Soc. 76, 3400 (1954). 5. G. Struve, J. prak. Chem..~0, 295 (1894); ibid. 52, 170 (1895). 6. A. I. Vogel, T. B. of Quantitative Inorganic Analyses 3rd Edn. pp. (a) 608, (b) 527, (c) 460, Longmans, London (1964). 7. R.H. Lee, E. Griswold and J. Kleinberg, lnorg. Chem. 3, 1278 (1964).

Coordination compounds of hydrazine derivatives with transition m e t a l s - 111 RESULTS

437

AND DISCUSSION

The reaction of aroyl hydrazones(i I)[R, R': C~H5 C6H5; C6H5, p-CH30"C6H4; o-OH'CsH4, C6H~; o-OH'C6H4; p-CH30"C~H4] with nickel(ll) chloride in ethanol yielded pale green compounds insoluble in almost all known solvents. Elemental analyses (Table 1) of these compounds suggest the general formula Ni(HL)2"CI2 where HL refers to the neutral ligand. The i.r. spectra of both the chelates and the parent ligands exhibit bands characteristic of the stretching vibration of N - - H and C~---O(amide 1), besides an amide 11 band[8] (Table 2). The presence of these bands suggests that the hydrazone residue reacted in the keto form. The C ~ O band of the nickel chelates is shifted to lower frequencies ( - 2 0 cm -1) as compared to that of the parent ligands; this gives an evidence that coordination occurs via the carbonyl oxygen atom. The band at 1602 cm -1 observed in the spectra of the ligands may be attributed to the phenyl ring conjugated to the azomethine group ( C ~ N ) . This band was found to be not affected on chelation. All the complexes of this series are paramagnetic with magnetic moment tx = 3-2 B.M./Ni atom, corresponding to octahedral environment. The electronic spectra, in N ujol, of these chelates show three weak bands characteristic of nickel (1I) complexes with a distorted octahedral coordination. The band at 23,530, 14,080 and 10,000 cm -1 may be tentatively identified as 3A2,, --~ 3Tlu(P), :~A2,I zTL~ and :~A2.,---~3T2, spin allowed transitions in the Oh symmetry[10]. The presence of the shoulder in the middle band (Fig. 1) can be assigned to the spin orbit coupling which mixes the very close in energy 3Tt,j(F) and 1E,, states [9]. The magnetic and spectral measurements reveal that in the solid state~ these chelates possess a distorted octahedral structure with the two chloride ions probably occupying the two transaxial positions. On the other hand, the reaction of the aroyl hydrazones(ll) JR, R', C~Hs, C~Hs, C6H5, p-CH30"CsH4; C6H5, C4H30(furyl); o-OH-C6H4, C6H5; o-OH" C6H4, p-CH30"CGH4] with nickel(lI) acetate in a (2: 1) molar ratio afforded red or orange crystalline chelates of the general formula Ni(L)2 where L refers to the monobasic ligand anion. The prepared bis-(N-substituted benzylidene aroyl hydrazinato) nickel(l l) complexes are insoluble in water, sparingly soluble in ethanol but soluble in benzene and chloroform. The i.r. spectra of these chelates show dramatic changes as compared with those of the parent ligands (Fig. 2). The bands due to (N--H) and ( C ~ O ) stretching vibrations, as well as, the amide II bands are absent in the spectra of nickel chelates. Instead a very sharp band is developed at 1602 cm 1. This band can be related to the stretching vibration mode of the conjugate - - C ~ N - - C ~ C - - g r o u p i n g analogous to that for azines [10]. These chelates are diamagnetic indicating square planar coordination. Their electronic spectra confirm this assignment. The spectra of these chelates in chloroform or in benzene consist of a very weak break shoulder in the visible region, having extinction coefficient of ---3 and three intense bands in the near u.v. region (Table 3). There are no absorption bands at wavelengths longer than 8. M. Mashima, Bull, chem. Soc. Japan 35, 1882 ( 1962); ibid. 36, 210 (1963). 9. C.J. Ballhausen, Introduction to Ligand Field Theory p. 26 I, McGraw-Hill, New York (1962). 10. R . G . R . Bacon and W. S. Lindsay, J. chem. Soc. 1382 (1958).

438

L. EL S A Y E D and M. F. I S K A N D E R

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about 700 m/z. The broad shoulder observed in the visible region may consist of more than one band due to the different d-d transitions in d 8 square planar complexes [l 1]. The other intense bands are due to charge transfer transitions. Table 3. Electronic spectra of some bis-(N-substituted benzylidene aroyl hydrazinato) Nickel(II) in chloroform g CsH5 p-CH30"C6H4 C4H30* C6H5

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*a-Furyl group. 11. H, B. Gray, Transition Metal Chemistry (Edited by R. L. Carlin), Vol. 1. p. 245. E. Arnold, London (1965).

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Fig. 2. The electronic spectra (in Nujol mull) of: (1) Dichloro bis-(N-benzylidene benzoyl hydrazine) nickel(lI): (2) Dichloro bis-(N-anisylidene benzoyl hydrazine) nickel(lI). Analogous to the reaction with nickel acetate, N-substituted benzylidene aroyl hydrazines 1I, [R, R', C6H5, C6H~; C6H,~, p-CH30"C6H4] reacted with copper(lI) acetate yielding the corresponding bis-(N-substituted benzylidene aroyl hydrazinato) copper(II) complexes. Analyses and i.r. spectra of these chelates suggest that the hydrazone residue reacted with copper(II) acetate in the enol form. The reaction in boiling ethanol between ligand 11 (R, R', C6H~, C6H5; C6H5, C~H,~, p-CHzO'C6H4; o-OH-C6H4, C~H~; o-OH.C~H4, p-CH30"C6H4) and cupric chloride dihydrate in a (2: 1) ratio results in the formation of yellow crystalline complexes with sharp decomposition temperatures. Analytical data (Table 1) show that the ratio of C u : N : C I are 1:2:1 indicating that only one ligand is involved in the reaction. These chelates are diamagnetic in the solid state. The diamagnetism suggests either the formation of a dimeric species in which paramagnetism is quenched through spin coupling[12] or the reduction of copper(II) yielding the copper(I) chelate. The i.r. spectra of all these complexes show a sharp band at 3223 cm -1 corresponding to sec N - - H stretching frequency besides the amide I band ( C ~ O ) at 1620 cm -1 (Fig. 3), The analytical and magnetic data together with the i.r. spectra can be rationalized on the basis that the ligands reacted with Cu(II) ion yielding the 12. c. M. Harris and R. L. Martin,Proc. chem. Soc. 259 (1958); M. Kato,H. B. J. Jonassenand J. C. Fanning,Chem. Rev. 64, 99 (1964).

442

L. EL SAYED and M. F. ISKANDER

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corresponding mono-(aroyl hydrazone) copper(I) monochloride. As a further evidence the electronic spectra in Nujol or in pyridine did not show bands characteristic to d-d transitions in Cu(II) ions. A general review on the previous results shows that aroyl hydrazones react with both nickel(II) and copper(II) acetates yielding the corresponding bis-(aroyl hydrazinato) metal(lI) complexes with the deprotonation of the secondary imino hydrogen. The liberated protons are continuously removed from the reaction medium through the formation of weakly ionized acetic acid. Due to the strong coordination tendency of the chloride ions, nickel(I1) chloride, on the other hand, gave the dichloro bis-(aroyl hydrazone) nickel(II) in which the hydrazone residue reacts as a neutral ligand. Treatment of the dichloro-bis-(aroyi hydrazone) nickel(II) with alkalies (2% alc. KOH) leads to deprotonation and displacement

Coordination compounds of hydrazine derivatives with transition m e t a l s - l I I

443

of two HCI molecules from the octahedral complex and the formation of square planar neutral compound. With Cu(II) chloride the reaction proceeds through the reduction of Cu(II) ions and the formation of mono(aroyl hydrazone) copper(I) monochloride. It is known that hydrazine [13] and its derivatives in alkaline solutions can easily reduce Cu(II) salts. However, acid hydrazides(1) (R = C6H5, o-HO'C6H4, and CH3) in ethanol yields with CuC12 blue crystalline Cu(lI) chelates of the general formula Cu(HL)2C12 without any sign of reduction[14]. Addition of aromatic aldehydes (R.CHO, R = C6H5, p-CH30"C6H4) to the blue hydrazide complexes in ethanol readily reduce Cu(lI) and the corresponding yellow cuprous hydrazone complexes are formed. It is noticed that aldehydes are not able to reduce Cu(II) under the same experimental conditions. The mechanism of reduction is not well established. However, it is probable that the reduction process may involve both the azomethine moiety and chloride ions. 13. A. Berka, J. Vulterin and J. Zyka, Chemist-Analyst 52, 52 (1963). 14. R.M. lssa, M. F. E1 Shazly and M. F. lskander, Z. anorg, allg,. Chem. 354, 90 (1967).