Hybrid molecular magnets obtained by insertion of decamethyl-metalloceniumcations into layered, bimetallic oxalate complexes: [Z(III)CP(2)*][(MMIII)-M-II(ox)(3)] (Z(III) = Co, Fe; M-III = Cr, Fe; M-II = Mn, Fe, Co, Cu, Zn; ox = oxalate; Cp* = pentamethylcyclopentadienyl)

A new series of hybrid organometallic - inorganic layered magnets with the formula [Z(III)Cp(2)*] [(MMIII)-M-II(ox)(3)] (Z(III) = Co, Fe; M-III = Cr, Fe; M-II = Mn, Fe, Co, Cu, Zn; ox = oxalate; Cp* = pentamethylcyclopentadie nyl) has been prepared. All of these compounds are isostructural and crysta llize in the monoclinic space group C2/m, as found by X-ray structure analy sis. Their structure consists of an eclipsed stacking of the bimetallic oxa late-based extended layers separated by layers of organometallic cations. T hese salts show spontaneous magnetization below T-c, which corresponds to t he presence of ferro-, ferri-, or canted antiferromagnetism. Compounds in w hich the paramagnetic decamethylferrocenium is used instead of the diamagne tic decamethylcobaltocenium are good examples of chemically constructed mag netic multilayers with alternating ferromagnetic and paramagnetic layers. T he physical properties of this series have been thoroughly studied by means of magnetic measurements and ESR and Mossbauer spectroscopy. We have found that be two layers are electronically quasiindependent. As a consequence, the bulk properties of these magnets have not been significantly affected b y the insertion of a paramagnetic layer of S = 1/2 spins in between the ext ended layers. In fact, the critical temperatures remain unchanged even when comparing [MCp2*](+) derivatives with [XR4](+) compounds (X = N, P; R = Ph , nPr, nBu). Nevertheless, the presence of the paramagnetic layer has been shown to have some influence on the hysteresis loops of these compounds. Tn the same context, the spin polarization of the paramagnetic units(which ar ises from the internal magnetic field created by the bimetallic layers in t he ordered stale) has been observed by Mossbauer and ESR spectroscopy.