Novel monomeric barium complexes as volatile precursors for chemical vapour deposition

A new range of barium complexes with single encapsulating ligands have been prepared for use in chemical vapour deposition (CVD). A novel pathway providing an unprecedented sequence of barium carbamates is reported. New dianionic bis β-ketoesterates and their barium, strontium and calcium derivatives were synthesised. High resolution mass spectrometry showed some barium derivatives to be monomeric, and preliminary testing indicated some volatility in these species. Calcium and strontium complexes were found to have nuclearities that varied according to their ionic radii relative to the chain length of the encapsulating ligand.