TY - JOUR
T1 - Self assembled tetranuclear Cu4(ii), Ni4(ii) [2 × 2] square grids and a dicopper(ii) complex of heterocycle based polytopic ligands - Magnetic studies
AU - Mandal, Tarak Nath
AU - Roy, Somnath
AU - Konar, Saugata
AU - Jana, Atanu
AU - Ray, Sangita
AU - Das, Kinsuk
AU - Saha, Rajat
AU - El Fallah, Mohamed Salah
AU - Butcher, Ray J.
AU - Chatterjee, Sudipta
AU - Kar, Susanta Kumar
PY - 2011/11/9
Y1 - 2011/11/9
N2 - The ditopic ligand PyPzOAP (N-[(Z)-amino(pyridin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid) and the polytopic ligand 2-PzCAP (N′3, N′5-bis[(1E)-1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3,5-dicarbohydrazide) were synthesized in situ by condensation of methyl imino picolinate with 5-methyl-1-(2-pyridyl) pyrazole-3-carbohydrazide and 2-acetyl pyridine with pyrazole-3,5-dicarbohydrazide respectively. The ligands PyPzOAP and PzOAP (reported earlier, Dalton Trans., 2007, 1229) self-assemble to form homoleptic [2 × 2] tetranuclear M4 (M = Cu(ii) and Ni(ii)) square grids structures [Cu4(PyPzOAP)4](NO3)4 (1), [Cu4(PzOAP)4](ClO4)4 (2) and [Ni4(PyPzOAP)4](NO3)4·8H2O·2CH3CN (3). While the ligand 2-PzCAP forms a dicopper(ii) complex [Cu2(2-PzCAP)(OH)(NO3)(H2O)](NO3)·2H2O (4). The complex 1 is a perfect square grid (a = 4.201 Å), whereas, 2 and 3 are almost square grids. All these compounds have been characterized by X-ray structural analyses and variable temperature magnetic susceptibility measurements. EPR studies have also been carried out for complexes 1, 2 and 4. In the Cu4 grid (1), all the Cu(ii) centers are in a distorted octahedral environment with N4O2 chromophore, while, in complex 2, all four Cu(ii) centers have a square pyramidal environment with N3O2 chromophore. In complex 3, all four Ni(ii) centers have distorted octahedral geometry with N4O2 chromophore. In compound 4, the Cu(ii) centers are in square pyramidal environment with N3O2 chromophore. The magnetic properties of compounds 1 and 2 show the presence of intramolecular ferromagnetic exchange interaction (J = 5.88 cm−1 for 1 and 4.78 cm−1 for 2). The complex 3 shows weak intramolecular antiferromagnetic interaction (J = −4.02 cm−1). While, complex 4, shows strong antiferromagnetic behavior (J = −443 cm−1).
AB - The ditopic ligand PyPzOAP (N-[(Z)-amino(pyridin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid) and the polytopic ligand 2-PzCAP (N′3, N′5-bis[(1E)-1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3,5-dicarbohydrazide) were synthesized in situ by condensation of methyl imino picolinate with 5-methyl-1-(2-pyridyl) pyrazole-3-carbohydrazide and 2-acetyl pyridine with pyrazole-3,5-dicarbohydrazide respectively. The ligands PyPzOAP and PzOAP (reported earlier, Dalton Trans., 2007, 1229) self-assemble to form homoleptic [2 × 2] tetranuclear M4 (M = Cu(ii) and Ni(ii)) square grids structures [Cu4(PyPzOAP)4](NO3)4 (1), [Cu4(PzOAP)4](ClO4)4 (2) and [Ni4(PyPzOAP)4](NO3)4·8H2O·2CH3CN (3). While the ligand 2-PzCAP forms a dicopper(ii) complex [Cu2(2-PzCAP)(OH)(NO3)(H2O)](NO3)·2H2O (4). The complex 1 is a perfect square grid (a = 4.201 Å), whereas, 2 and 3 are almost square grids. All these compounds have been characterized by X-ray structural analyses and variable temperature magnetic susceptibility measurements. EPR studies have also been carried out for complexes 1, 2 and 4. In the Cu4 grid (1), all the Cu(ii) centers are in a distorted octahedral environment with N4O2 chromophore, while, in complex 2, all four Cu(ii) centers have a square pyramidal environment with N3O2 chromophore. In complex 3, all four Ni(ii) centers have distorted octahedral geometry with N4O2 chromophore. In compound 4, the Cu(ii) centers are in square pyramidal environment with N3O2 chromophore. The magnetic properties of compounds 1 and 2 show the presence of intramolecular ferromagnetic exchange interaction (J = 5.88 cm−1 for 1 and 4.78 cm−1 for 2). The complex 3 shows weak intramolecular antiferromagnetic interaction (J = −4.02 cm−1). While, complex 4, shows strong antiferromagnetic behavior (J = −443 cm−1).
UR - http://www.scopus.com/inward/record.url?scp=80755175235&partnerID=8YFLogxK
U2 - 10.1039/c1dt10813a
DO - 10.1039/c1dt10813a
M3 - Article
AN - SCOPUS:80755175235
SN - 1470-479X
VL - 40
SP - 11866
EP - 11875
JO - Journal of the Chemical Society. Dalton Transactions
JF - Journal of the Chemical Society. Dalton Transactions
IS - 44
ER -