TY - JOUR
T1 - A rare pentanuclear cadmium(II) complex and two new mononuclear zinc(II) complexes of pyrazole derived ditopic ligands-Synthesis, crystal structures and spectral studies
AU - Konar, Saugata
AU - Jana, Atanu
AU - Das, Kinsuk
AU - Ray, Sangita
AU - Golen, James A.
AU - Rheingold, Arnold L.
AU - Kar, Susanta Kumar
PY - 2013/3/1
Y1 - 2013/3/1
N2 - Pyrazole based ditopic ligand HL1 ((Z)-N′-(5-methyl-1H- pyrazole-3-carbonyl) picolinohydrazonamide) reacts with Cd(ClO4) 2·6H2O and Zn(ClO4)2· 6H2O to form a self assembled pentanuclear Cd(II) complex [Cd 5(L1)6](ClO4)4 (1) and a mononuclear Zn(II) complex [Zn(HL1)2](ClO 4)2 (2). On the other hand, HL2 ((Z)-N′-(5-methyl-1H-pyrazole-3-carbonyl) pyrazine-2-carbohydrazonamide) also forms a mononuclear [Zn(HL2)](ClO4) 2(MeOH)2 (3) with Zn(ClO4)2.6H 2O. All these complexes have been characterized crystallographically and spectroscopically. The Cd(II) complex (1) has a pentanuclear core with trigonal bipyramidal arrangement of Cd(II) atoms, where, the axial metal centers (Cd2 and Cd5) have N3O3 chromophore and the equatorial centers (Cd1, Cd3 and Cd4) have N4O2 chromophore with distorted octahedral arrangement around the metal centres. In 2 and 3, the NNO donor ligand molecules in their ketoimine form produce distorted octahedral environment around the Zn(II) centre with N4O2 chromophore utilizing pyridine/pyrazine N, one azomethine N and one carbohydrazide O atoms. Here, the pyrazole ring N atoms remain silent in coordination process. On the other hand, in 1, the same ligand HL1 coordinates in its deprotonated imineol form and functions as N3O donor, while, the pyrazole N atoms take part in coordination process. Ligands HL1 and HL2 are fluorescence silent but complexes 1, 2 and 3 show considerable fluorescence. The fluorescence intensity of 1 is higher than that of 2 and 3.
AB - Pyrazole based ditopic ligand HL1 ((Z)-N′-(5-methyl-1H- pyrazole-3-carbonyl) picolinohydrazonamide) reacts with Cd(ClO4) 2·6H2O and Zn(ClO4)2· 6H2O to form a self assembled pentanuclear Cd(II) complex [Cd 5(L1)6](ClO4)4 (1) and a mononuclear Zn(II) complex [Zn(HL1)2](ClO 4)2 (2). On the other hand, HL2 ((Z)-N′-(5-methyl-1H-pyrazole-3-carbonyl) pyrazine-2-carbohydrazonamide) also forms a mononuclear [Zn(HL2)](ClO4) 2(MeOH)2 (3) with Zn(ClO4)2.6H 2O. All these complexes have been characterized crystallographically and spectroscopically. The Cd(II) complex (1) has a pentanuclear core with trigonal bipyramidal arrangement of Cd(II) atoms, where, the axial metal centers (Cd2 and Cd5) have N3O3 chromophore and the equatorial centers (Cd1, Cd3 and Cd4) have N4O2 chromophore with distorted octahedral arrangement around the metal centres. In 2 and 3, the NNO donor ligand molecules in their ketoimine form produce distorted octahedral environment around the Zn(II) centre with N4O2 chromophore utilizing pyridine/pyrazine N, one azomethine N and one carbohydrazide O atoms. Here, the pyrazole ring N atoms remain silent in coordination process. On the other hand, in 1, the same ligand HL1 coordinates in its deprotonated imineol form and functions as N3O donor, while, the pyrazole N atoms take part in coordination process. Ligands HL1 and HL2 are fluorescence silent but complexes 1, 2 and 3 show considerable fluorescence. The fluorescence intensity of 1 is higher than that of 2 and 3.
KW - Cadmium
KW - Crystal structure
KW - Photoluminescence
KW - Pyrazole derived ditopic ligands
KW - Zinc
UR - https://www.scopus.com/pages/publications/84875264266
U2 - 10.1016/j.ica.2012.12.003
DO - 10.1016/j.ica.2012.12.003
M3 - Article
AN - SCOPUS:84875264266
SN - 0020-1693
VL - 397
SP - 144
EP - 151
JO - Inorganica Chimica Acta
JF - Inorganica Chimica Acta
ER -