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(mu-bpypz)2].

The synthesis and characterization of new spin-crossover pyrazolato bridged dinuclear [(FeII(NCS)(py))2(mu-bpypz)2] and the corresponding cyanotrihydroborato-kappaN 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.