Synthesis and reactivity of rare-earth metal phosphaethynolates

Over the course of the last six years, research on the synthesis and reactivity of molecular metal phosphaketenes (M-PCO) has gained increasing attention. However, lanthanide complexes of the heavier group 15 cyanate analogue PCO − have not been investigated so far. Herein we present exemplar studies on the nature and reactivity of rare-earth phosphaethynolato-complexes using three characteristic representatives of the rare-earth metals: Y, Nd and Sm. Our investigations comprise both +2 and +3 redox states, and one defined amidinate-based ligand set, as well as novel reaction pathways in the presence of the sequestering agents 18-crown-6 and 2,2,2-crypt. The reactivity and coordination behaviour of OCP − towards three rare-earth elements: Y, Nd and Sm, was investigated. Mono- and bis-phosphaethynolate complexes in different oxidation states were prepared, leading to novel coordination modes of OCP − and ionic intermediates of Sm( ii ) in the presence of 18-crown-6 or 2,2,2-crypt.