Supramolecular motifs and solvatomorphism within the compounds [M(bpy)_3]_2[NbO(C_2O_4)_3]Cl•nH_2O (M=Fe^2+, Co^2+, Ni^2+, Cu^2+ and Zn^2+; n=11, 12). Syntheses, structures and magnetic properties

Jurić, Marijana and Perić, Berislav and Brničević, Nevenka and Planinić, Pavica and Pajić, Damir and Zadro, Krešo and Giester, Gerald and Kaitner, Branko (2008) Supramolecular motifs and solvatomorphism within the compounds [M(bpy)_3]_2[NbO(C_2O_4)_3]Cl•nH_2O (M=Fe^2+, Co^2+, Ni^2+, Cu^2+ and Zn^2+; n=11, 12). Syntheses, structures and magnetic properties. Dalton Transactions (6). pp. 742-754. ISSN 0300-9246

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Abstract

Solvatomorphism has been found between two series of complexes of the composition [M(bpy)_3]_2[NbO(C_2O_4)_3]Cl•nH_2O [M = Fe^2+(1, 2), Co^2+(3, 4), Ni^2+(5, 6), Cu^2+(7) and Zn^2+(8, 9); bpy=2,2'-bipyridine)], crystallizing in the monoclinic space group P2_1/c[3, 5, 8 (n=11)] or in the orthorhombic space group P2_12_12_1[2, 4, 6, 7 (n= 12)]. All the structures contain two symmetry independent [M(bpy)_3]^2+ cations, one [NbO(C_2O_4)_3]^3- anion, one Cl– anion, and crystal water molecules. The cations possess a trigonally distorted octahedral geometry, with an additional tetragonal distortion in 7. Analysis of crystal packing reveals a specific type of supramolecular contact comprising four bipyridine ligands from two neighbouring [M(bpy)_3]^2+ cations – quadruple aryl embrace (QAE) contact. The contact is realized by the alignment of two molecular two-fold rotation axes, preserving the parallel orientation of the molecular three-fold rotation axes. The resulting two-dimensional honeycomb lattices of [M(bpy)_3]^2+ cations are placed between the hydrogen bonding layers made of [NbO(C_2O_4)_3]^3– and Cl– anions and the majority of crystal water molecules. The temperature-dependent magnetic susceptibility measurements (1.8–300 K) show a significant orbital angular momentum contribution for 3 and 4 (high-spin Co^2+), the influence of zero-field splitting for 5 and 6 (Ni^2+) and a substantially paramagnetic Curie behaviour for the Cu^2+ compound (7).

Item Type: Article
Date: 2008
Subjects: NATURAL SCIENCES > Physics
Divisions: Faculty of Science > Department of Physics
Publisher: The Royal Society of Chemistry
Depositing User: mag. bibl. Marija Turković
Date Deposited: 27 Jun 2014 18:16
Last Modified: 18 Jul 2014 09:50
URI: http://digre.pmf.unizg.hr/id/eprint/2408

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