SPIN CROSSOVER AND TEMPERATURE SENSITIVITY OF PARAMAGNETIC NMR CHEMICAL SHIFTS IN AN AQUEOUS SOLUTION OF THE IRON(II) NAPHTHALENESULFONATE COMPLEX WITH TRIS(PYRAZOL-1-YL)METHANE [Fe(HC(Pz)3)2](C10H7SO3)2

Paramagnetic chemical shifts in the iron(II) tris(pyrazole-1-yl)methane [Fe(HC(Pz) 3 ) 2 ](C 10 H 7 SO 3 ) 2 complex exhibiting spin crossover were studied by 1 H NMR at different temperatures. The studied complex demonstrates a relatively sharp temperature change of NMR chemical shifts due to spin crossover. Complex [Fe(HC(Pz) 3 ) 2 ](C 10 H 7 SO 3 ) 2 can be considered a promising compound for the design of thermally sensitive shift and relaxation NMR probes utilized for local temperature measurements in aqueous media and for advanced MRI diagnostics.