Dynamics of BF 4 - anion reorientation in the spin-crossover compound [Fe(1-n-propyl-1H-tetrazole) 6 ](BF 4 ) 2 and in its Zn II analogue
- 55 Downloads
19 F and 11 B spin-lattice relaxation times were measured in [Zn(ptz) 6 ] (BF 4 ) 2 \(\) and in the spin-crossover compound [Fe(ptz) 6 ] (BF 4 ) 2 . For both compounds BF 4 - anion reorientation is active above 50 K. For [Zn(ptz) 6 ] (BF 4 ) 2 , the anion-reorientation dynamics is different in the temperature regions of 50-90 K, 90-120 K, and above 150 K; between 120 and 150 K it changes rapidly reflecting a structural change. In [Fe(ptz) 6 ] (BF 4 ) 2 the mechanism for the paramagnetic relaxation involving the 19 F nuclei is found to be of the diffusion-limited type according to the theory of Lowe and Tse. The present results prove that the spin-crossover takes place in a dynamic surrounding and not in a static crystal lattice.
Unable to display preview. Download preview PDF.