A highly polar hybrid perovskite of [FCH2CH2NH3][Mn(HCOO)(3)]

A new hybrid perovskite of [FCH2CH2NH3][Mn(HCOO)(3)] has been successfully prepared by utilizing the ammonium of FCH2CH2NH3+, and it is the first example incorporating F-substituted ammonium in the class of ammonium metal formate framework. The compound crystallizes in polar, orthorhombic space group Pna2(1), and the cell parameters are a=8.5901(3)-8.7158(6), b=8.4613(3)-8.5216(6), c=12.4837(4)-12.6106(9) angstrom and V=907.36(5)-936.6(1) angstrom(3) from 80 K up to 410 K just before the decomposition, showing positive thermal expansions in all directions and no structural phase transition in the temperature region. The FCH2CH2NH3+ cation in the cavity of the NaCl-like Mn-formate framework adopts N-C-C-F gauche conformation, and its NH3+ and F ends are anchored to the anionic framework by N-H center dot center dot center dot O and C-H center dot center dot center dot F H-bonds. The large dislocation of the NH3+ end from the anionic framework, about 1.4 angstrom, results in an estimated high electric polarization about 10 mu Ccm(-2) for the polar structure. The material is also a spin-canted antiferromagnet with the Neel temperature of 8.3 K.