title: NH4FeCl2(HCOO): synthesis, structure, and magnetism of a novel low-dimensional magnetic material.
abstract: Solvothermal synthesis was used to create a low-dimensional iron(II) chloride formate compound, NH4FeCl2(HCOO), that exhibits interesting magnetic properties. NH4FeCl2(HCOO) crystallizes in the monoclinic space group C2/c (No. 15) with a = 7.888(1) Å, b = 11.156(2) Å, c = 6.920(2) Å, and β = 108.066(2)°. The crystal structure consists of infinite zigzag chains of distorted Fe(2+)-centered octahedra linked by μ2-Cl and syn-syn formate bridges, with interchain hydrogen bonding through NH4(+) cations holding the chains together. The unique Fe(2+) site is coordinated by four equatorial chlorides at a distance of 2.50 Å and two axial oxygens at a distance of 2.08 Å. Magnetic measurements performed on powder and oriented single-crystal samples show complex anisotropic magnetic behavior dominated by antiferromagnetic interactions (TN = 6 K) with a small ferromagnetic component in the direction of chain propagation. An anisotropic metamagnetic transition was observed in the ordered state at 2 K in an applied magnetic field of 0.85-3 T. (57)Fe Mössbauer spectroscopy reveals mixed hyperfine interactions below the ordering temperature, with strong electric field gradients and complex noncollinear arrangement of the magnetic moments.
authors.affiliation: Department of Chemistry, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Greenfield
authors.forename: Saeed
authors.initials: S
authors.lastname: Kamali
authors.forename: Nezhueyotl
authors.initials: N
authors.lastname: Izquierdo
authors.forename: Michael
authors.initials: M
authors.lastname: Chen
authors.forename: Kirill
authors.initials: K
authors.lastname: Kovnir
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D003460:Crystallization; D005296:Ferrous Compounds / Q000737:chemistry*; D008280:Magnetics; D033362:Powder Diffraction; D015204:Spectroscopy, Mossbauer
chemical_list: D005296:Ferrous Compounds; D000641:Ammonia; C029451:ferrous chloride