Layered molecule-based magnets formed by decamethylmetallocenium cations and two-dimensional bimetallic complexes [M(II)Ru(III)(ox)(3)](-)(M(II) = Mn, Fe, Co, Cu and Zn; ox = oxalate)

A new series of hybrid organometallic-inorganic layered magnets with formul a [Z(III)Cp(2)(*)] [(MRuIII)-Ru-II(ox)(3)] (Z(III) = Co and Fe; M-II = Mn, Fe, Co, Cu, and Zn; ox = oxalate: Cp* = pentamethylcyclopentadienyl) has be en prepared. All of these compounds are isostructural to the previously rep orted [Z(III)Cp(2)*] [(MMIII)-M-II(ox)(3)] (M-III = Cr, Fe) series and crys tallize in the monoclinic space group C2/m, as found by powder X-ray diffra ction analysis. They are novel examples of magnetic materials formed by bim etallic oxalate-based extended layers separated by layers of organometallic cations, The magnetic properties of all these compounds have been investig ated (ac and de magnetic susceptibilities and field dependence of the isoth ermal magnetization at 2 K), In particular, it has been found that Fe-II an d Co-II derivatives behave as magnets with ordering temperatures of 12.8 an d 2.8 K, respectively, while no long-range magnetic ordering has been detec ted down to 2 K in the Mn-II and Cu-II derivatives. The magnetic ordering i n the Fe-II derivatives has been confirmed through Mossbauer spectroscopy. This technique has also made it possible to observe the spin polarization o f the paramagnetic [FeCp2*](+) units caused by the internal magnetic field created by the bimetallic layers in the ordered state. (C) 2001 Academic Pr ess.