Issue 2, 2012
From the journal:

Dalton Transactions

Synthesis, structural, magnetic, DFT calculations and CShM studies of three new pentanuclear Mn(ii) clusters†‡

T. N. Mandal,a   S. Roy,a   S. Konar,a   A. Jana,a   K. Das,a   S. Ray,a   S. Gupta,a   R. Saha,b   M. S. El Fallah,*c   J. Tercero,d   R. J. Butcher,e   S. Chatterjeef  and  S. K. Kar*a  

* Corresponding authors

a Department of Chemistry, University College of Science, University of Calcutta, 92, A.P.C. Road, Kolkata, India
E-mail: skkar_cu@yahoo.co.in

b Department of Physics, Jadavpur University, Kolkata, India

c Departament de Química Inorgànica, and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Martí i Franquès 1-11, Barcelona, Spain
E-mail: salah.elfallah@qi.ub.es

d Departament de Química Inorgànica, and Institut de Química Teòrica i Computacional, Universitat de Barcelona, Martí i Franquès 1-11, Barcelona, Spain

e Department of Chemistry, Howard University, 2400 Sixth Street, N. W., Washington, DC, U. S. A.

f Department of Chemistry, Serampore College, Serampore, Hooghly, India

Abstract

The ditopic ligand PyPzOAPz (N-[(Z)-amino(pyrazin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid) was synthesized by in situ condensation of methyl imino pyrazine-2-carboxylate with 5-methyl-1-(2-pyridyl) pyrazole-3-carbohydrazide. In this work we have also used two of our earlier ligands PzCAP (5-methyl-N-[(1E)-1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazonic acid) (Dalton Trans., 2009, 8215) and PzOAP (N-[(Z)-amino(pyridin-2-yl)methylidene]-5-methyl-1H-pyrazole-3-carbohydrazonic acid) (Dalton Trans., 2007, 1229). These ligands PzCAP, PzOAP and PyPzOAPz were made to react with Mn(ClO4)2·6H2O to produce three pentanuclear Mn(II) clusters [Mn5(PzCAP)6](ClO4)4 (1), [Mn5(PzOAP)6](ClO4)4 (2) and [Mn5(PyPzOAPz)6](ClO4)4 (3). These complexes have been characterized by X-ray structural analyses and variable temperature magnetic susceptibility measurements. All complexes have a pentanuclear core with trigonal bipyramidal arrangement of Mn(II) atoms, where, the axial metal centers have a N3O3 chromophore and the equatorial centers have N4O2 with an octahedral arrangement. These Mn5(II) clusters 1, 2 and 3 show the presence of antiferromagnetic coupling within the pentanuclear manganese(II) core (J = −2.95, −3.19 and −3.00 cm−1 respectively). Density functional theory calculations and continuous shape measurement (CShM) studies have been performed on these complexes to provide a qualitative theoretical interpretation of the antiferromagnetic behaviour shown by them. The pentanuclear Mn(II) cluster (1) on reaction with Cu(NO3)2·6H2O in 1 : 1 mole proportion in CH3OH:H2O (60 : 40) forms a homoleptic [2 × 2] tetranuclear Cu4(II) grid [Cu4(PzCAP)4(NO3)2](NO3)2·8H2O (4). The same Cu4(II) grid is also obtained from a direct reaction between the ditopic ligand PzCAP with Cu(NO3)2·6H2O in 1 : 1 mole proportion. This conversion of a cluster to a grid is a novel observation.

Graphical abstract: Synthesis, structural, magnetic, DFT calculations and CShM studies of three new pentanuclear Mn(ii) clusters

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Article information

DOI
https://doi.org/10.1039/C1DT11458A
Article type
Paper
Submitted
02 Aug 2011
Accepted
08 Sep 2011
First published
21 Oct 2011

Dalton Trans., 2012,41, 413-423

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Synthesis, structural, magnetic, DFT calculations and CShM studies of three new pentanuclear Mn(II) clusters

T. N. Mandal, S. Roy, S. Konar, A. Jana, K. Das, S. Ray, S. Gupta, R. Saha, M. S. El Fallah, J. Tercero, R. J. Butcher, S. Chatterjee and S. K. Kar, Dalton Trans., 2012, 41, 413 DOI: 10.1039/C1DT11458A

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