Unusual coordination modes of multidentate ligands; Crystal structure of [{ {(tmhd)³Y} }²(hmteta)][tmhd = But COCHCOBu^t and hmteta = Me²N(CH²CH²NMe)²CH ²CH²NMe²]

The reaction of the hydrated lanthanide metal β-diketonate complexes [Ln(tmhd)₃(H₂O)] (tmhd=Bu^tCOCHCOBu^t) with hexamethyltriethylenetetramine (hmteta=Me₂N(CH₂CH₂NMe)₂CH ₂CH₂NMe₂) in n-hexane at room temperature yields the anhydrous, bridged dimeric complexes, [{(tmhd)₃Ln}₂(hmteta)], where Ln=Gd 1 or Y 2. An X-ray study of 2 shows that only three of the four possible nitrogen atoms of the hmteta ligand are utilised in bonding to the yttrium centres. The complexes are air and moisture stable, and more importantly both have good volatility, thermal stability, and mass transport properties as demonstrated by sublimation, differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), thus making them potential precursors for MOCVD application.