Synthesis and Characterization of Volatile, Thermally Stable, Reactive Transition Metal Amidinates

A series of homoleptic metal amidinates of the general type [M(R-R‘AMD)n]x (R = iPr, tBu, R‘ = Me, tBu) has been
prepared and structurally characterized for the transition metals Ti, V, Mn, Fe, Co, Ni, Cu, Ag, and La. In oxidation
state 3, monomeric structures were found for the metals Ti(III), V(III), and La(III). Bridging structures were observed
for the metals in oxidation state 1. Cu(I) and Ag(I) are held in bridged dimers, and Ag(I) also formed a trimer that
cocrystallized with the dimer. Metals in oxidation state 2 occurred in either monomeric or dimeric form. Metals with
smaller ionic radii (Co, Ni) were monomeric. Larger metals (Fe, Mn) gave monomeric structures only with the
bulkier tert-butyl-substituted amidinates, while the less bulky isopropyl-substituted amidinates formed dimers. The
new compounds were found to have properties well-suited for use as precursors for atomic layer deposition (ALD)
of thin films. They have high volatility, high thermal stability, and high and properly self-limited reactivity with molecular
hydrogen, depositing pure metals, or water vapor, depositing metal oxides.