Spectroscopic and Magnetic Properties of a Series of mu-Cyano Bridged Bimetallic Compounds of the Type M-II-NC-Fe-III (M = Mn, Co, and Zn) Using the Building Block [Fe-III(CN)(5)imidazole](2-)

摘要

In this contribution, we describe the preparation and single-crystal X-ray diffraction of a new building block for bimetallic solid state materials. X-ray diffraction data of these complexes indicate that (PPh4)(2)[Fe(CN)(5)imidazole]center dot 2H(2)O crystallizes in the triclinic space group P (1) over bar with a = 9.8108(15) angstrom, b = 11.1655(17) angstrom, c = 23.848(4) angstrom, alpha = 87.219(2)degrees, beta = 85.573(2)degrees, gamma = 70.729(2)degrees, and Z = 2, while its precursor Na-3[Fe(CN)(5)(en)]center dot 5H(2)O crystallizes in the monoclinic space group P2(1)/n with a = 8.3607(7) angstrom, b = 11.1624(9) angstrom, c = 17.4233(14) angstrom, beta = 90.1293(9)degrees, and Z = 4. Spectroscopic and magnetic properties of a series of bimetallic materials were obtained by reaction of the complex [Fe(CN)(5)imidazole](2-) with hydrated transition metal ions [M(H2O)(n)](2+) (M = Mn, Co, Zn; n = 4 or 6). The new bimetallic materials obtained are [Co(H2O)(2)][Fe(CN)(5)imidazole]center dot 2H(2)O (1), [Mn(CH3OH)(2)][Fe(CN)(5)imidazole] (2), Zn[Fe(CN)(5)imidazole]center dot H2O (3), and [Mn(bpy)][Fe(CN)(5)imidazole]center dot H2O (4). All of the complexes crystallize in the orthorhombic system. X-ray single-crystal analysis of the compounds identified the Imma space group with a = 7.3558(10) angstrom, b = 14.627(2) angstrom, c = 14.909(2) angstrom, and Z = 4 for 1; the P2(1)2(1)2(1) space group with a = 7.385(5) angstrom, b = 13.767(9) angstrom, c = 14.895(10) angstrom, and Z = 4 for 2; the Pnma space group with a = 13.783(2) angstrom, b = 7.167(11) angstrom, c = 12.599(2) angstrom, and Z = 4 for 3; and the Pnma space group with a = 13.192(3) angstrom, b = 7.224(16) angstrom, c = 22.294(5) angstrom, and Z = 4 for 4. The structures of 1, 2, and 4 consist of two-dimensional network layers containing, as the repeating unit, a cyclic tetramer [M2Fe2(CN)(4)] (M = Mn, Co). H bonding between the layers in the structure of 1 results in a quasi-three-dimensional network. The structure of 3 was found to be three-dimensional, where all of the cyano ligands are involved in bridging between the metal centers. The bridging character of the cyano is confirmed spectroscopically. The magnetic properties have been investigated for all of the bimetallic systems. Compound 1 shows ferromagnetic behavior with an ordering temperature at 25 K, which is higher than the corresponding Prussian Blue analogue Co-x[Fe(CN)(6)]y center dot zH(2)O. Compound 2 shows weak ferromagnetic behavior and an interlayer antiferromagnetic character, while 3, as expected, shows paramagnetic character due to the diamagnetic character of Zn2+. Compound 4 shows antiferromagnetic behavior.