Synthesis and properties of organic derivatives of some F-elements

Abstract

A new class of organolanthanides containing both pi and metal-carbon sigma bonds have been synthesized and characterized. These are ring-bridged biscyclopentadienyl lanthanides of the type [Cp(CH2)xCp]LnCl and [Cp(CH2)3Cp]LnR (Cp-cyclopentadienyl; x = 3 or 4; Ln = La and Ce) or phenyl in the case of lanthanum. Proton nmr and infrared spectra reported are consistent with the structure proposed for these complexes including the assignment of a monosubstituted phenyl group. In the case of cerium complexes, magnetic studies indicate that there is some interaction other than strictly ionic. Studies in solution by ultraviolet spectroscopy point out the possibility of THF coordinating with some of these complexes. Thermally unstable, aryl uranium compounds, prepared at low temperature in situ, have been successfully used for the trimerization of alkynes to arenes.