Cationic rare-earth metal bis(tetrahydridoborato) complexes: direct synthesis, structure and ring-opening polymerisation activity toward cyclic esters†
Abstract
Rare-earth metal tris(borohydrides) [Ln(BH4)3(thf)3] (Ln = Y, La, Nd, Sm) are converted with one equivalent of the Brønsted acid [NEt3H]+[BPh4]− in thf into the monocationic bis(borohydride) complexes [Ln(BH4)2(thf)5]+[BPh4]−. They efficiently initiate the ring-opening polymerisation of