Structural and Spectral Study of Copper(II) Complexes of Pyridilbis{3-piperidyl-,bis{hexamethyleneiminyl-,bis{N(4)-diethyl-, andbis{N(4)-dipropylthiosemicarbazones}

Abstract

Pyridil bis(N(4)-substituted thiosemicarbazones) have been prepared in which the substituents in place of the NH 2 group in the thiosemicarbazone moieties are piperidinyl (H 2 Plpip), hexamethyleneiminyl (H 2 Plhexim), diethylaminyl (H 2 Pl4DE), and dipropylaminyl (H 2 Pl4DP). IR, electronic, mass, and ESR spectra of their copper(II) complexes are reported. Crystal structure determinations of H 2 Pl4DE and three of the copper(II) complexes of formula [Cu(Plpip)], [Cu(Plhexim)] and [Cu(Pl4DE)] 2´2 [Cu(Pl4DE)], are included. H 2 Pl4DE lacks hydrogen bonding between the thiosemicarbazone moieties, but each moiety is in the Z confi-guration form with hydrogen bonding from the thiosemicarbazone moieties to the pyridyl nitrogen atoms. The crystal used for the structure determination of [Cu(Plhexim)] was isolated from an electrochemical preparation. In all the new compounds the deprotonated ligands are N,N,S,S-tetradentate, coordinating to the copper(II) centre through their azomethine nitrogen atoms and their thiocarbonyl sulfur atoms.

Bonding and structure trends of thiosemicarbazone derivatives of metals—An overview

“…The presence of pyridyl substituents at C 2 carbon favours tricoordination, and the geometry is restricted to tetracoordination with Bis-thiosemicarbazones entrap a metal ion in view of their geometry, and invariably formed square planar [CuL] complexes, 289-305 [251,[270][271][272][273][274][275][276][277] (Chart 34). In complexes 289-304, the bisligands are dinegative tetradentate coordinating via N 2 S 2 donor atoms, whereas in complex 305, the bis-ligand is neutral.…”

“…Thiosemicarbazones with 2-hydroxyphenyl as a substituent at C 2 carbon act as dinegative tridentate N 3 , S-chelation and Obridging ligands (deprotonation of -OH and -N 2 H groups) in [Cu 2 L 2 ] 359, 360 [21,298], and uninegative N 3 , S-chelation and Obridging in [Cu 2 L 2 (OH 2 )]·2NO 3 ·H 2 O 361 [301,302] [64,270,271,275,[303][304][305]. The geometry of complex 362 is trigonal bipyramidal formed by anionic thiosemicarbazone ligand (deprotonation of -OH group) [269].…”

Luminescent complexes of silver(i) with pyridylbis(3-hexamethyleneiminyl thiosemicarbazone): effect of the counterion on the nuclearity

“…The formation of these complexes involves the reduction of Au (III) to Au(I) and the oxidation of the bis(thiosemicarbazone) to elemental sulfur. 14 With other transition metal ions such as Ni (II), 15 Pd(II) 13 and Cu(II), 16 the complexes formed are monomers and the bis(thiosemicarbazone) acts as an N 2 S 2 tetradentate ligand. However, in the case of Pd(II) a dimeric compound was isolated in which each thiosemicarbazone moiety acts as an N 2 S tridentate ligand.…”

“…The silver atoms are considered to be 4-coordinate and are coordinated by two phosphine phosphorus atoms, a thiolate sulfur atom and one imine nitrogen, with the bis(thiosemicarbazone) bridging the two silver atoms in a tetradentate fashion. The silver(I) center has a distorted tetrahedron or see-saw coordination geometry, with bond angles around the silver atom varying from 73.39 (16)°for N(12)-Ag(1)-S(1) to 125.33 (8)°for P(1)-Ag(1)-P(2) (Table 1).…”