| SM ISO690:2012|
FILIPPOVA, Irina; RADU, Ioana; STYNGACH, Evgenia; MACAEV, Fliur; HAUSER, J; DECURTINS, Silvio; LIU, Shixia; BACA, Svetlana. Crystal structures of Co(II) COMPLEXES WITH A TETRA-2-pyridynylpyrazine ligand. In: Materials Science and Condensed Matter Physics. Editia a 8-a, 12-16 septembrie 2016, Chişinău. Chişinău: Institutul de Fizică Aplicată, 2016, p. 195. ISBN 978-9975-9787-1-2.
|Materials Science and Condensed Matter Physics
Editia a 8-a, 2016
Conferința "International Conference on Materials Science and Condensed Matter Physics" |
8-th Edition, Chişinău, Moldova, 12-16 septembrie 2016
During the past years polynuclear transition metal coordination clusters attracted much attention due to their huge potential as building block for new magnetic materials. In continuation of our research on the construction of polynuclear clusters with interesting magnetic properties two new complexes [CoII2(piv)2(tpp)2Cl2]·2(MeCN)·(H2O) (1) and [CoIII(tpp)(CN)3]·2(MeCN) (2) have been prepared from the reaction of a dinuclear Co(II) pivalate precursor [Co2(-OH)2(piv)4(Hpiv)4] with polydentate tetra-2-pyridinylpyrazine (tpp) and 2-[bis(2-hydroxyethyl)amino]acetonitrile (CN-dea) ligands. Compound 1 is the dominant product of the reaction and crystallizes as brown prisms in the monoclinic space group P21/c. The crystal is built of centrosymmetric dinuclear complexes [Co2(piv)2(tpp)2Cl2] (Fig. 1), H2O and MeCN as solvate molecules. Co atom has a highly distorted octahedral geometry containing three nitrogen atoms from tpp ligand, two oxygen atoms from carboxylate group of pivalate molecule and Cl atom. Deformation of CoII coordination polyhedron is observed both in bond lengths (range from 2.071(2) to 2.347(1) Å) and angles (61.34(8)º for chelating carboxylate group). The shortest distance between Co atoms is 6.723(1) Å. The tpp ligand is non-planar. Two pyridyl groups coordinated to the one CoII ion are tilted above the plane of the central pyrazine ring, while the other two pyridyl groups coordinated to symmetrically related CoII ion are tilted below the plane of the pyrazine. Compound 2 was isolated as a minor light yellow crystalline product. It also crystallizes in the space group P21/c. Crystal structure consists of discrete mononuclear complexes [CoIII(tpp)(CN)3]·(Fig. 2) and acetonitrile solvate molecules. Co atom has a slightly distorted octahedral configuration with three coordinated CN- ion and N atoms from tridentate tpp ligand. The bond lengths in CoIII octahedron are in the range 1.875 - 1.940 Å. Within the tpp ligand the dihedral angles between pyrazine ring and coordinated pyridyl groups are only 11.4º and 14.1º. Two other pyridyl groups are strongly turned from the central ring. The equivalent angles for the noncoordinating pyridyl groups are 41.1° and 63.8°. Acknowledgement. Authors thank SCOPES IZ73Z0_152404/1 for financial support.