The reactions of FeX 3 (X=Cl and Br) and pz ∗ H (pz ∗ H=pyrazole, or substituted pyrazole) in CH 2 Cl 2 have led to three types of mononuclear complexes: mer-[FeX 3 (pz ∗ H) 3 ], trans-[FeX 2 (pz ∗ H) 4 ] − and trans-[FeX 2 (pz ∗ H) 4 ]. The latter type, containing Fe II -centers results from spontaneous reduction of the Fe III starting material. The X-ray crystal structures of eleven such complexes and the 57 Fe-Mössbauer spectra of three of them are reported.