Synthesis and X-ray structure of a borohydrido metallocene of neodymium and its use as pre-catalyst in Nd/Mg dual-component ethylene and isoprene polymerisations

Cp2∗Nd(BH4)(THF) (1) (Cp* = C5Me5) has been readily obtained in one step from Nd(BH4)3(THF)3 and fully characterised by 1H NMR, IR spectroscopy, and elemental analysis. Its X-ray structure displays a neutral monomeric complex, bearing one slightly distorted terminal BH4 group. Associated to nBuEtMg (1) affords a highly active catalyst for ethylene polymerisation, the first one prepared from a borohydrido organolanthanide pre-catalyst. In the same experimental conditions, the catalytic behaviour of 1 is similar to that of previously described Cp2∗NdCl2Li(Et2O)2(2). The 1/nBuEtMg system is not deactivated even in the presence of large excesses of THF. In contrast to its chloro homologue 2, the addition of 1 equiv. of nBuEtMg to 1 affords a catalyst for a trans-selective polymerisation of isoprene.

Graphical abstractMonomeric Cp2∗NdBH4(THF) has been synthesised and fully characterised. Combined with butylethylmagnesium (BEM), it gives rise to a powerful ethylene polymerisation catalyst, the first one made of a borohydrido organolanthanide. Cp2∗NdBH4(THF)/BEM also allows isoprene polymerisation, in contrast with the corresponding chloro neodymocene.Figure optionsDownload full-size imageDownload as PowerPoint slide