The Preparation of Some Thiosemicarbazones and Their Copper Complexes

Abstract

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).

Synthesis and properties of some formylferrocene thiosemicarbazones

“…Attempts to prepare copper complexes with 2-substituted thiosemicarbazones failed; only starting materials were recovered from the reaction mixtures. This is in agreement with previous work on copper complex formation with a variety of substituted thiosemicarbazones (19). Copper complexes (2:l) were prepared from compounds 3, 4, and 5 (4-substituted compounds) and the infrared spectra of these complexes are given in Table I1 (spectra 14 to 16).…”

“…In the spectrum of compound 1, formylferrocene-2-methylthiosemicarbazone, a strong band appears at 1585 cm-'. This shift to higher frequency has been observed before (19) in a comparison of 2-and 4-substituted thiosemicarbazones. The band which is observed at 1510 or 1500 cm-' in the spectra of compounds 3 to 7 may be attributed to aromatic ring absorptions (see, for example, ref.…”

The C=S stretching vibration in the infrared spectra of some thiosemicarbazones

“…Gingras et al (9) assigned bands in the region of 1 130 to 1 080 cm-l in the spectra of several thiosemicarbazones to the C=S vibration because a band in this region disappears on copper complex formation. ILlashima (4) has published the infrared spectra of hydrazine-N,N1-bis-thiocarbonic Can For personal use only.…”

“…Selenium analogues of all these thio compounds were prepared by the method of Huls and Renson (12). Cu(1) complexes (1:l) of the thiosemicarbazones were made by reaction with cuprous chloride as described by Gingras et al (9). N-Methyl derivatives of some of the aldehyde thiosemicarbazones were prepared.…”

Antimicrobial Screening of Co(ii), Ni(ii) and Cu(ii) Complexes with Nitrogen and Oxygen Containing Schiff Base

“…It is established from the literature 13 that semicarbazone ligand can coordinate in a bidentate manner in most cases through azomethine nitrogen and carbonyl oxygen of semicarbazone moiety.…”