# Synthesis, characterization and reactivity of a series of alkaline earth and rare earth iminophosphoranomethanide complexes

## TL;DR

Researchers synthesized and characterized new organometallic complexes using iminophosphoranomethanide ligands, which could serve as useful precursors for creating new materials.

## Contribution

The study explores the use of iminophosphoranomethanide ligands as alkyl precursors in deprotonation reactions for synthesizing alkaline earth and rare earth complexes.

## Key findings

- Bis- and tris-methanide complexes were successfully synthesized using two distinct methods.
- Rare earth methanides were shown to act as synthetic precursors for solvent-free complexes.
- Electronic structures of rare earth methanides were analyzed using advanced techniques like EPR and ab initio calculations.

## Abstract

There is a great demand from the synthetic community for readily accessible organometallic alkaline earth and rare earth compounds that can be used as synthons for the preparation of new complexes and materials. Here we report the use of the methanide ligand {CH(SiMe3)P(Ph)2 = NSiMe3}– (NPC-H) in the stabilization of alkaline earth and rare earth organometallics and their potential use as synthetic precursors. Bis- and tris-methanide complexes were obtained following two methods: (1) deprotonation of the proligand with organometallic precursors; (2) salt elimination reactivity between potassium methanide and metal iodides. All compounds were characterised by multinuclear nuclear magnetic resonance, infra-red spectroscopy, elemental analysis, ultraviolet-visible spectroscopy and single crystal X-ray diffraction. Additionally, selected rare earth methanides were tested as synthetic precursors for the preparation of solvent-free rare earth complexes. Finally, the electronic structures of open-shell divalent rare earth methanides were probed using electron paramagnetic resonance, magnetometry studies and ab initio calculations.

Iminophosphoranomethanide ligands have been used to stabilize metal complexes, but their application as alkyl precursors in deprotonation reactions remains unexplored. Here, the authors prepare and characterize bis- and tris- methanide alkaline and rare earth complexes through protonolysis between dibenzyl metal precursors and the CH2(SiMe3)P(Ph)2 = NSiMe3 proligand or salt elimination reactions, and show that rare earth methanides can be used as synthetic precursors for the preparation of solvent-free complexes.