Hydrothermal synthesis, crystal structure, thermal behavior, ferromagnetic resonance and ferrimagmetic behavior of (C4H12N2)1.5[Fe3(HAsO4)1.02(HPO4)0.98(AsO4)0.88(PO4)0.12F5]

(C4H12N2)1.5[Fe3(HAsO4)1.02(HPO4)0.98(AsO4)0.88(PO4)0.12F5] has been synthesized by using mild hydrothermal conditions under autogeneous pressure. The crystal structure was solved from X-ray single crystal data. The compound crystallizes in the monoclinic P21/c space group. The unit cell parameters are image, image, image, image with image. The crystal structure is formed from [Fe3(HAsO4)1.02(HPO4)0.98(AsO4)0.88(PO4)0.12F5]3− sheets with the piperazinium cations located in the interlayer space, compensating the anionic charge and establishing hydrogen bonds. The IR and Raman spectroscopies confirm the existence of both the arsenate/hydrogenarsenate and phosphate/hydrogenphosphate oxoanions and the presence of the piperazinium dication. The reflectance diffuse spectrum is in good agreement with the existence of iron(III) high spin cations in slightly distorted octahedral geometry. The values of the Dq and Racah parameters are image, image and image. The ESR spectroscopy shows the presence of ferromagnetic resonance. The g-value shifts from 1.99(1) in the 300–15 K range to 3.11(1) at lower temperatures. Magnetic measurements indicate the presence of a ferrimagnetic behavior with the existence of a weak hysteresis loop at 5 K.