Two new two-dimensional organically templated phosphite compounds:: (C6H16N2)0.5[M(HPO3)F], M = Fe(II) and Co(II):: Solvothermal synthesis, crystal structures, thermal, spectroscopic, and magnetic properties

The organically templated (C6H16N2)(0.5)[M(HPO3)F] [M(II) = Fe (1) and Co (2)] compounds have been synthesized by using mild hydrothermal conditions under autogeneous pressure. The crystal structures have been determined from X-ray single-crystal diffraction data. The compounds are isostructural and crystallize in the C2/c monoclinic space group. The unit-cell parameters are a = 5.607(1), b = 21.276(4), c = 11.652(1) angstrom, beta = 93.74(1)degrees for the iron phase and a = 5.5822(7), b = 21.325(3), c = 11.4910(1) angstrom, 93.464(9)degrees for the cobalt compound with Z = 4. The crystal structure of these compounds consists of [M(HPO3)F](-) anionic sheets. The layers are constructed from chains which contain [M2O6F3] dimeric units linked by fluoride ions. The trans-1,4-diaminocyclohexane cations are placed in the interlayer space. The IR and Raman spectra show the bands corresponding to the phosphite oxoanion and organic dication. The Dq and Racah (B and C) parameters have been calculated from the diffuse reflectance spectra in the visible region. Dq parameter is 790 cm(-1) for compound (1). For phase (2) the Dq value is 725 cm(-1) and B and C are 930 and 4100 cm(-1), respectively. The thermal evolution of the molar magnetic susceptibilities of these compounds show maxima at 20.0 and 6.0 K for the iron(II) and cobalt(II) phases, respectively. These results indicate the existence of antiferromagnetic interactions in both compounds. (c) 2005 Elsevier Inc. All rights reserved.