Speaker
Ms
Gabriela Handzlik
(Faculty of Chemistry, Jagiellonian University, Kraków)
Description
In our contribution we describe syntheses, single-crystal X-ray crystallographic structures and magnetic properties of a new family of cyanide-bridged coordination polymers {(NH4)[(H2O)MnII-(μ-L)-MnII(H2O)] [NbIV(CN)8].xH2O}n MnNbL with supporting ligands L = cyanide, formate, acetate and propionate (x = 2 or 3).
MnNbL stems from a prototypical three-dimensional cyanide-bridged {[MnII(H2O)2]2[NbIV(CN)8].4H2O}n MnNb compound [1] which shows ferrimagnetic behaviour with magnetic ordering temperature Tc = 50 K. Each bridging CN- in MnNb connects the MnII (d5 configuration, S = 5/2) and NbIV (d1, S = 1/2) metal centres and enables relatively strong antiferromagnetic exchange interactions JNbMn within the NbIV-CN-MnII motif.
We have managed to introduce the extra ligands that connect each two neighbouring MnII centres. The ligands were introduced at the self-assembly stage. This was done by taking advantage of the potential ‘cavities’ within the MnNb framework with the Mn-Mn distance of 6.147 Å. Additional bridging ligands change this distance to 5.631 Å in case of cyanide or 6.253 Å for formate and tune in this way the structural properties of the -Nb-CN-Mn- framework. Moreover, the bridging of the two MnII centres in MnNbL introduces additional magnetic interaction pathways with significant JMnMn¬ < 0. The new compounds show a unique magnetic behavior that might be related to magnetic frustration within a triangle of three antiferromagnetically coupled magnetic centres: two MnII and one NbIV (Figure 1). These new octacyanometallate-based compounds with additional bridging ligands demonstrate how chemists can exert considerable control over the magnetic behaviour of molecular magnets.
Literature:
[1] J. M. Herrera, P. Franz, R. Podgajny, M. Pilkington, M. Biner, S. Decurtins, H. Stoeckli-Evans, A. Neels, R. Garde, Y. Dromzee, M. Julve, B. Sieklucka, K. Hashimoto, S. Ohkoshi, M. Verdaguer, C. R. Chimie 11 (2008), 1192-1199
Primary authors
Dr
Dawid Pinkowicz
(Faculty of Chemistry, Jagiellonian University, Kraków)
Ms
Gabriela Handzlik
(Faculty of Chemistry, Jagiellonian University, Kraków)
Co-authors
Prof.
Barbara Sieklucka
(Faculty of Chemistry, Jagiellonian University, Kraków)
Dr
Wojciech Nitek
(Faculty of Chemistry, Jagiellonian University, Kraków)
