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The Effect of C‐2 Substituents of Salicylaldehyde‐Based Thiosemicarbazones on the Synthesis, Spectroscopy, Structures, and Fluorescence of Nickel(II) Complexes
Author(s) -
Lobana Tarlok S.,
Kumari Poonam,
Castineiras Alfonso,
Butcher Ray J.
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201300209
Subject(s) - chemistry , nickel , salicylaldehyde , ligand (biochemistry) , stereochemistry , fluorescence , 2,2' bipyridine , bipyridine , yield (engineering) , medicinal chemistry , crystallography , crystal structure , organic chemistry , biochemistry , receptor , schiff base , physics , quantum mechanics , materials science , metallurgy
The aim of this investigation was to study the bonding patterns, geometry, and fluorescence properties of nickel(II) complexes with salicylaldehyde‐based thiosemicarbazones [(2‐OH‐5‐R 1 ‐C 6 H 3 )C(R 2 )=NNHC(=S)NHR 3 , LH 2 ] by invoking the effect of substituents at the C‐2 and N‐1 atoms of the thio ligands and by using bipyridines/phenanthrolines as auxiliary ligands. The methodology used for the preparation of complexes involved initial binding of Ni II with a thio ligand in an organic solvent to yield an insoluble solid of empirical composition [NiL], which was reacted further with a N,N‐donor ligand. In this way, we have prepared a series of dinuclear complexes and two mononuclear complexes with stoichiometries [Ni 2 L 2 (bipy)(D)] [bipy = 2,2′‐bipyridine, L = L 1 (R 1 , R 2 , R 3 = H), D = H 2 O 1 ; L = L 2 (R 1 , R 2 = H, R 3 = Me), D = CH 3 OH 2 ; L = L 3 (R 1 , R 2 = H, R 3 = Et), D = CH 3 OH 4 ; L = L 3 , D = H 2 O 5 ; L = L 4 (R 1 = Me, R 2 = H, R 3 = Me), D = CH 3 OH 6 ], [Ni 2 L 3 2 (bipy)] ( 3 ), [Ni 2 L 3 2 (dmbipy)(H 2 O)] ( 7 , dmbipy = 4,4′‐dimethyl‐2,2′‐bipyridine), [Ni 2 L 5 2 (bipy) 2 ] ( 8 , R 1 = NO 2 , R 2 = H, R 3 = Me), [Ni L 6 (bipy)] ( 9 , R 1 = NO 2 , R 2 = H, R 3 = Et), [Ni L 7 (bipy)(H 2 O)] ( 10 , R 1 = H, R 2 = Me, R 3 = Et), [Ni 2 L 3 2 (4,4′‐bipy)] ( 11 , 4,4′‐bipy = 4,4′‐bipyridine), and [Ni 2 L 7 2 (4,4′‐bipy)] ( 12 ). The dinuclear complexes involve (i) O,N 3 ,S chelation with bridging N 2 atoms to form trigonal‐bipyramidal/square‐planar complexes with a five‐coordinate and a four‐coordinate Ni center ( 3 , 5:4‐coordination) and octahedral/square‐planar complexes ( 1 , 2 , 4 – 7 , 6:4‐coordination), (ii) O,N 3 ,S chelation with S bridges to form octahedral/octahedral complexes ( 8 , 6:6‐coordination), and (iii) O,N 3 ,S chelation to form square‐planar/square‐planar complexes ( 11 , 12, 4:4‐coordiantion). The mononuclear complexes involve O, N 3 ,S chelation and have square‐pyramidal ( 9 ) and octahedral ( 10 ) geometries. Complexes 1 – 10 are paramagnetic with μ eff value in the range 2.97–3.38 μ B . Complexes 2 and 3 exhibit fluorescence emission.