XCIX.—Reactions of thiosemicarbazones. Part I. Action of halogen compounds

Wilson, Forsyth James; Burns, Robert

doi:10.1039/ct9222100870

Cited by 20 publications

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“…On the other hand lnost tscs dissolve in alkali (13,14) and form metallic complexes in alkaline solution ( 5 , 8,11) thus suggesting the important role of one of the anions (V) in solution. The observation that N2-methyl tscs (I, R3 = Me) do not dissolve in alkali (13) and that h3-clrazides of type (R-CO-NH-NRR)…”

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The Preparation of Some Thiosemicarbazones and Their Copper Complexes

Gingras¹,

Somorjai²,

Bayley³

1961

Can. J. Chem.

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Reactions of N-and S-substitutetl thiosemicarbazones with Cu(1) have been examined. No complexes are formed when the S atom is substituted and(or) when the N2 hydrogen atom is replaced by Me. 4,i-Dimethyl derivatives not only give the itsual 1:l conlplexes, but also 2:l complexes (2 thiosemicarbazoncs to 1 copper) in which copper has been oxidized t o Cu(I1). Reactions of thiosetuicarbazones with Cu(I1) give 1:1,2:1, and probably a mixture which corresponds to 2:s complexes. A discussion on the possible structures for the 1:1 complexes is given and they are best represented as polymers, the metal being borlded to the sulphur and to a nitrogen atom of the thiosemicarbazide portion of the ~nolecule. Infrared spectra of these c o m p o u~~d s have been examined, particularly in the 1100 cm-1 region where a strong to medium band disappears in going fro111 thiosemicarbazones to copper complexes. I t is suggested that this band is due to the C=S \vibration.Various metallic complexes of organic sulphur compounds are described in the literature (1-10). Many of these were prepared for phpsiological studies and their structures are not discussed fully (7, 10). I n earlier publications we have reported the preparation of Cu (I) complexes of tl~iosemicarbazones* (1 tsc :l Cu) (1 1) and their fungicidal action (12). This paper presents a discussion of the possible structures for these complexes based mainly on the reactions of several N-inethyl tl~ioseinicarbazones with copper ions in ammoniacal and neutral media.Thiosen~icarbazo~les have the structure (I) ( R = alkyl, aryl, or H).When Rg and R4 and(or) K j are hydrogen atoms, tautoineric thiols (11) and (IV) and thione (111) forms are possible, these being interconvertible through their common anions (V) and cations (VI). The dipolar structures (IIIal and (IIIb) may contribute to (111).

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confidence: 99%

The Preparation of Some Thiosemicarbazones and Their Copper Complexes

Gingras¹,

Somorjai²,

Bayley³

1961

Can. J. Chem.

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“…This is in agreement with siluilar findings that open-chain tscs exist only in the thiono form in the solid state (Is), and 3-mercapto-5-oxo-1,2,4-triazines were recently shown to exist in the lceto and thiono forms in neutral solution (16). I-Iowever, there is little doubt that in the presence of a base, the thione thiol tautoillerisnl takes place since both tscs and thiotriazine dissolve in alliali, and the S-Kc's salt of acetone tsc has already been described (17). As a comparison, the analogous 3-oxy-1,2,4-triazine (VIII) was prepared and its infrared For personal use only.…”

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The Preparation of Some Thiosemicarbazones and Their Copper Complexes: Part Iii

Gingras¹,

Suprunchuk²,

Bayley³

1962

Can. J. Chem.

112

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Reactions of some diketones with thiosemicarbazide have been studied under various conditions. Monothiosemicarbazones, dithiosemicarbazones, and cyclization products call be obtained. It was found that dithiosemicarbazones form 1:l complexes with Cu(I1) but failed to react with Cu(1). Dithiosen~icarbazones in which the Nxhydrogen atom has been replaced by Me do not form complexes, conlirining our views about the irnporta~lce of this hydrogen atom in the thione ++ thiol tautomerism necessary for complex formation. 4,4-D~methyldithiosemicarbazones behave like the in substituted parent coinpounds in forming 1:l complexes with Cu(I1). Infrared spectra provide evidence for the structure of a cyclizatioil product, 5,6-diphenyl-3-thio-l,2,4-triazine, which had been erroneously described by various authors as the thiol tautomer, 5,6-diphenyl-3-n1ercapto-1,2,4-triazinc.In previous publications (1, 2), the reactions of thiosemicarbazones (tscs) with Cu (1) and Cu(I1) ions were reported. A polymeric structure was suggested for the insoluble 1:l coluplexes obtained froin these reactions (2), and the antifungal activity of both free tscs and their copper coinplexes \iras also reported (3). T h e present worl; describes the reactio~ls of mono-and di-tscs with a number of metals. I t was found t h a t monotscs which form colllplexes readily with copper in allialine or neutral solution fail to react similarly with the follo\\ring nletals: &(I), EIg(II), Ni(II), Mn(II), %n(II), Sn(II), Co(II), Fe(II), and Fe(II1). Guha-Sircar ct al. (4) obtainecl solid precipitates fro111 tscs and several of these metals a t pI-I from 3 to 7, and suggested that this 1-eaction could be used for the quantitative deterinination of cations. 111 the present ~o l -l i , precipitates were ol~tained with the catio~is mentio~led above but no definite products were isolated. T h e high lnetal content (approx. 5070) indicated that these solid matel-ials wei-e inostly inorganic, consisting probably of the metal sulphides.T h e fact that tscs for111 definite complexes i~rith copper only, coupled with our previous finding t h a t antifungal activity is usually limited t o the free tscs, the complexes being inactive (3), is believed to be quite significant in the study of the mechanisnl of antifungal action of these compounds. The role and the nature of the metal in biological processes involving metal-binding substailces is of great importance (5) and \\70rli is currently being carried out along this line and \\?ill be reported elsewhere.A number of ditl~iosemicarbazo~~es (clitscs) were prepared froill dicarbonyl compou~lds in order t o examine their reaction with metals and eventually t o study their antifullgal properties. T h e reaction of dicarbonyl compounds with thiosemicarbazide is not simple and ll~istures of products are usually obtained. T h e separation of these nlixtures is complicated by the low solubility of the various components and the discrepancies encountered in the literature co~lcerning their melting points.Clyosal (I) (R = R' = I...

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“…Benzophenone thiosemicarbazone (I) was prepared by the known procedure (13) and its S-benzyl derivative (II) was obtained by benzylation with benzyl chloride in the presence of sodium ethoxide (14).…”

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confidence: 99%