Synthesis, crystal structure, spectroscopic and photoluminescence studies of manganese(II), cobalt(II), cadmium(II), zinc(II) and copper(II) complexes with a pyrazole derived Schiff base ligand

Saugata Konar, Atanu Jana, Kinsuk Das, Sangita Ray, Sudipta Chatterjee, James A. Golen, Arnold L. Rheingold, Susanta Kumar Kar

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

Varying coordination modes of the Schiff base ligand H2L [5-methyl-1-H-pyrazole-3-carboxylic acid (1-pyridin-2-yl-ethylidene)-hydrazide] towards different metal centers are reported with the syntheses and characterization of four mononuclear Mn(II), Co(II), Cd(II) and Zn(II) complexes, [Mn(H2L)(H2O)2](ClO 4)2(MeOH) (1), [Co(H2L)(NCS)2] (2), [Cd(H2L)(H2O)2](ClO4)2 (3) and [Zn(H2L)(H2O)2](ClO4) 2 (4), and a binuclear Cu(II) complex, [Cu2(L) 2](ClO4)2 (5). In the complexes 1-4 the neutral ligand serves as a 3N,2O donor where the pyridine ring N, two azomethine N and two carbohydrazine oxygen atoms are coordinatively active, leaving the pyrazole-N atoms inactive. In the case of complex 5, each ligand molecule behaves as a 4N,O donor utilizing the pyridine N, one azomethine N, the nitrogen atom proximal to the azomethine of the remaining pendant arm and one pyrazole-N atom to one metal center and the carbohydrazide oxygen atom to the second metal center. The complexes 1-4 are pentagonal bipyramidal in geometry. In each case, the ligand molecule spans the equatorial plane while the apical positions are occupied by water molecules in 1, 3 and 4 and two N bonded thiocyanate ions in 2. In complex 5, the two Cu(II) centers have almost square pyramidal geometry (τ = 0.05 for Cu1 and 0.013 for Cu2). Four N atoms from a ligand molecule form the basal plane and the carbohydrazide oxygen atom of a second ligand molecule sits in the apex of the square pyramid. All the complexes have been X-ray crystallographically characterized. The Zn(II) and Cd(II) complexes show considerable fluorescence emission while the remaining complexes and the ligand molecule are fluorescent silent.

Original languageEnglish
Pages (from-to)2801-2808
Number of pages8
JournalPolyhedron
Volume30
Issue number17
DOIs
StatePublished - 3 Nov 2011

Keywords

  • Cadmium(II)
  • Cobalt(II)
  • Emission properties
  • Manganese(II)
  • Pyrazole derived Schiff base ligand
  • Spectral studies
  • X-ray crystal structures
  • Zinc(II) and copper(II) complexes

Fingerprint

Dive into the research topics of 'Synthesis, crystal structure, spectroscopic and photoluminescence studies of manganese(II), cobalt(II), cadmium(II), zinc(II) and copper(II) complexes with a pyrazole derived Schiff base ligand'. Together they form a unique fingerprint.

Cite this