SYNTHESIS AND MAGNETIC STUDIES OF THE METALLOCARBORANE SANDWICH SALTS [FE(C(5)ME(5))(2)][M(C2B9H12)(2))] (M=CR,FE,NI)

The salts [Fe(C(5)Me(5))(2)][M(C2B9H11)(2))], (M = Cr, Fe, Ni), have been prepared by metathesis of [Fe(C(5)Me(5))(2)]Cl and [(CH3)(4)N][M(C2B9H11)(2))], (M = Cr, Fe, Ni), and the three salts have been shown to be isostructural from powder X-ray diffraction studies. The structure of the salt [Fe(C(5)Me(5))(2)][Fe(C2B9H11)(2))] has been determined by a single crystal X-ray diffraction study. The anions and cations pack in a distorted CsCl-type structure in which the distortion is thought to arise from the non-spherical shape of the [Fe(C2B9H11)(2))](-) anion. The sold-state magnetic susceptibility data for all three salts can be fitted to the Curie-Weiss law between 6 and 296 K. Low values of theta indicate there are no significant ferromagnetic or antiferromagnetic interactions between the unpaired spins, even at low temperatures.