SYNTHESIS, STRUCTURE AND PROPERTIES OF [HPY](2)[(M(MNT)(2))(2)] (M=COOR FE, HPY=PYRIDINIUM, MNT=MALEONITRILEDITHIOLATE)

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-crysta l X-ray diffraction, magnetic susceptibility measurements and IR and F e-57 Mossbauer spectroscopies. The compounds are isostructural, monocl inic, space group P2(1)/n with Z = 2. They both consist in alternate p acking of [{M(mnt)(2)}(2)](2-) units, with the metal in a square-pyram idal environment co-ordinated by sulfur atoms. and pyridinium cations bridged by three-centred hydrogen bonds to the mnt ligands. Iron-57 Mo ssbauer spectroscopy confirmed the presence of five-co-ordinate Fe-III atoms. Magnetic susceptibility measurements on the cobalt compound sh owed a small (approximate to 1.5 x 10(-4) emu mol(-1) at room temperat ure) paramagnetism, almost temperature independent below 150 K (approx imate to 0.7 x 10(-4) emu mol(-1)). while the iron analogue had a stro ng paramagnetic contribution of antiferromagnetically coupled pairs of S=3/2 in the [{Fe(mnt)(2)}(2)](2-) units, with -2J/k(B) = 515 K. Thes e properties are correlated to the crystal structure and compared with other [{M(mnt)(2)}(2)](2-) compounds with M = Fe or Co.