名称:
Synthesis, structure and properties of [Hpy]2[{M(mnt)2}2](M = Co or Fe, Hpy = pyridinium, mnt = maleonitriledithiolate)
摘要:
The compounds [Hpy](2)[{M(mnt)(2)}(2)] [M = Fe or Co, Hpy = pyridinium, mnt = maleonitriledithiolate (2,3-disulfanylmaleonitrile)] have been prepared by electrocrystallization and characterized by single-crystal X-ray diffraction, magnetic susceptibility measurements and IR and Fe-57 Mossbauer spectroscopies. The compounds are isostructural, monoclinic, space group P2(1)/n with Z = 2. They both consist in alternate packing of [{M(mnt)(2)}(2)](2-) units, with the metal in a square-pyramidal environment co-ordinated by sulfur atoms. and pyridinium cations bridged by three-centred hydrogen bonds to the mnt ligands. Iron-57 Mossbauer spectroscopy confirmed the presence of five-co-ordinate Fe-III atoms. Magnetic susceptibility measurements on the cobalt compound showed a small (approximate to 1.5 x 10(-4) emu mol(-1) at room temperature) paramagnetism, almost temperature independent below 150 K (approximate to 0.7 x 10(-4) emu mol(-1)). while the iron analogue had a strong paramagnetic contribution of antiferromagnetically coupled pairs of S=3/2 in the [{Fe(mnt)(2)}(2)](2-) units, with -2J/k(B) = 515 K. These properties are correlated to the crystal structure and compared with other [{M(mnt)(2)}(2)](2-) compounds with M = Fe or Co.