Ceramics-Silikáty 49 (3) 181-187 (2005)

SYNTHESIS, STRUCTURAL AND MAGNETIC PROPERTIES OF TM²⁺₂[Mo^IV(CN)₈]·nH2O

Z. Mitróová, M. Mihalik, A. Zentko, M. Bokor, K. Kamarás, V. Kavečanský, J. Kováč, K. Csach, J. Trpčevská

Octacyanomolybdates (OCMs) TM²⁺₂[Mo(CN)₈]·nH2O, where TM is Mn, Fe, Co, Ni, Cu were synthesised and characterised by IR spectroscopy and UV-VIS spectroscopy. The UV-VIS spectrum showed the intervalence charge transfer (IVCT) band between MoIV-CN-CuII and MoV-CN-CuI around 510 nm. Studied OCMs adopt tetragonal crystal structure. The 1H NMR signals reflect the magnetic moment of the TM²⁺ ions (µP). The decay rates of free induction decay (FID) signals increase as µP and the applied static rf -field increases. The spin - lattice relaxation times at 27.7 MHz vary from 0.0187 ms (Mn) up to 0.45 ms (Cu). Magnetization measurements indicate long-range magnetic ordering of Mn- and Co- OCMs with the Curie temperature T_c = 4 K. The remaining OCMs (TM is Fe, Ni, Cu) are paramagnetic down to T=1.9 K.

Keywords: Octacyanocomplexes, Crystal structure, NMR spectroscopy, Magnetic properties