Synthesis, structural, magnetic, DFT calculations and CShM studies of three new pentanuclear Mn(ii ) clusters
| Autor: | Shuvayan Roy, Sangita Ray, Susanta Kumar Kar, Javier Tercero, Saugata Konar, Ray J. Butcher, Subodh Gupta, Tarak Nath Mandal, Rajat Saha, Sudipta Chatterjee, Kuheli Das, Atanu Jana, M. S. El Fallah |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Models
Molecular Manganese Stereochemistry Ligand Molecular Conformation chemistry.chemical_element Crystallography X-Ray Ligands Magnetic susceptibility Inorganic Chemistry Magnetics Trigonal bipyramidal molecular geometry Crystallography chemistry.chemical_compound Hydrazines chemistry Octahedron Coordination Complexes Magnets Cluster (physics) Pyrazoles Density functional theory Homoleptic |
| Zdroj: | Dalton Trans.. 41:413-423 |
| ISSN: | 1477-9234 1477-9226 |
| DOI: | 10.1039/c1dt11458a |
| Popis: | 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(ClO(4))(2)·6H(2)O to produce three pentanuclear Mn(II) clusters [Mn(5)(PzCAP)(6)](ClO(4))(4) (1), [Mn(5)(PzOAP)(6)](ClO(4))(4) (2) and [Mn(5)(PyPzOAPz)(6)](ClO(4))(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 N(3)O(3) chromophore and the equatorial centers have N(4)O(2) with an octahedral arrangement. These Mn(5)(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(NO(3))(2)·6H(2)O in 1:1 mole proportion in CH(3)OH:H(2)O (60 : 40) forms a homoleptic [2 × 2] tetranuclear Cu(4)(II) grid [Cu(4)(PzCAP)(4)(NO(3))(2)](NO(3))(2)·8H(2)O (4). The same Cu(4)(II) grid is also obtained from a direct reaction between the ditopic ligand PzCAP with Cu(NO(3))(2)·6H(2)O in 1:1 mole proportion. This conversion of a cluster to a grid is a novel observation. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|