Magnetic behavior and Mossbauer spectra of spin-crossover pyrazolate bridged dinuclear diiron(II) complexes:: X-ray structures of high-spin and low-spin [{Fe(NCBH3)(py)}2(μ-bpypz)2]

The synthesis and characterization of new spin-crossover pyrazolato bridged dinuclear [{Fe-II(NCS)(py)}(2)(mu-bpypz)(2)] and the corresponding cyanotrihydroborato-.N complexes are described together with the X-ray crystal analysis of the latter in both the high-spin and low-spin states as well as the variable temperature magnetic susceptibility and/or Mossbauer spectra demonstrating the spin-crossover which exhibits an one-step process, but not a two-step one characteristic of the known bpym bridged dinuclear complexes.