Issue 44, 2011

Self assembled tetranuclear Cu4(ii), Ni4(ii) [2 × 2] square grids and a dicopper(ii) complex of heterocycle based polytopic ligands - Magnetic studies

Abstract

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 (N3,N5-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).

Graphical abstract: Self assembled tetranuclear Cu4(ii), Ni4(ii) [2 × 2] square grids and a dicopper(ii) complex of heterocycle based polytopic ligands - Magnetic studies

Supplementary files

Article information

Article type
Paper
Submitted
02 May 2011
Accepted
23 Aug 2011
First published
05 Oct 2011

Dalton Trans., 2011,40, 11866-11875

Self assembled tetranuclear Cu4(II), Ni4(II) [2 × 2] square grids and a dicopper(II) complex of heterocycle based polytopic ligands - Magnetic studies

T. N. Mandal, S. Roy, S. Konar, A. Jana, S. Ray, K. Das, R. Saha, M. S. El Fallah, R. J. Butcher, S. Chatterjee and S. K. Kar, Dalton Trans., 2011, 40, 11866 DOI: 10.1039/C1DT10813A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements