Template Synthesis and X-Ray Structure Determination of Unsymmetrical Tetradentate Schiff Base Complexes of Nickel(ii) and Copper(ii)

<b>Studies on some VO(IV), Ni(II) and Cu(II) complexes of non-symmetrical tetradentate Schiff-bases</b>

“…Their electronic spectra are typically characterized by the existence of complicated equilibria involving these different structural types [26]. However, the spectra of the Ni(II) complexes studied here, show two absorption bands around 17.60 and 23.68 kK, respectively, typical of a 4-coordinate square planar geometry and are assigned to 1 A 1g → 1 B 1g and 1 A 1g → 1 A 2g transitions [19]. The absence of a band at 16.00 kK, 3 T 1 (F) → 3 T 1 (P), in the spectra of these complexes, implies the absence of tetrahedral forms of these complexes.…”

“…and squareplanar complexes are diamagnetic [23]. The Ni(II) complexes reported in this work, are diamagnetic and consequently, four coordinate, square planar in geometry [19][20]23], ruling out the presence of paramagnetic, tetrahedral forms.…”

“…These ligands are widely studied because of their pronounced coordinating properties and stability [8][9]. A number of symmetrical Schiff bases and chelates have been reported [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], while comparatively little is known on synthesis and physico-chemical properties of asymmetric Schiff-base ligands and metal complexes [16][17][18][19][20]. Consequently, the aim of this work is to synthesize and characterize unsymmetrical Schiff-base ligands (derived from condensation of 1-phenyl-1,3-butanedione/2,4-pentanedione, ethylenediamine and 5-methoxy-2-hydroxy acetophenone) and their VO(IV), Ni(II) and Cu(II) complexes, in order to see the effect of the mixed π-electron ligand system and phenyl/methyl substituent on geometries and physico-chemical properties.…”

Synthesis, characterization and antimicrobial studies of Ru(II) complexes with Schiff base co-ligand derived from 5,6-diamino -1,10- phenanthroline and benzene -1,4-dicarbaldehyde

“…Schiff base possess functional group containing nitrogen double bond with the nitrogen atom linked to an aryl or alkyl group, with the exception of hydrogen (Kostova and (Lashanizadegan and Jamshidbeigi, 2011). Presence of aryl substituents usually eases the synthesis and stability of Schiff bases while those containing alkyl are relatively unstable.…”

Synthesis and Characterization of Cobalt(II) and Nickel(II) Complexes of Some Schiff Bases Derived from 3-hydrazino-6-methyl[1,2,4] triazin-5(4H)one

“…is additional evidence for the square-planar geometry around the cobalt(II) ion [17][18][19]. In case of nickel(II) complexes, the diamagnetism of the complexes as well as the occurrence of two bands in the regions 18,900-20,000 and 24,200-24,770 cm )1 assignable to 1 A 1g fi 1 B 2g , 1 A 1g fi 1 B 1g transitions, are consistent with a squareplanar structure [17,20,21] of all the nickel(II) complexes.…”