Calcium β-diketiminates
π-β-diketiminato ligands, due to their large steric hindrance, have been proposed as possible ligands for synthesis of volatile, oxygen-free alkaline earth (f.e. Ca) complexes, which can be potentially applied for MOCVD preparation of Ca-containing layers, for example oxygen-free CaS films or CaTiO3 layers [[i]]
[i]Winter, Charles H., ADA429770, Final rept. 1 May 2001-31 Oct 2004
WAYNE STATE UNIV DETROIT MI DEPT OF CHEMISTRY
“New Lanthanide Precursors for Doping Semiconductor Films”
Ca bis-β-diketiminates with tBuNC(CH3)CHC(CH3)NtBu ligand were prepared by protonolysis reaction using Ca(N(SiMe3)2)2(THF)2. The attempted synthesis by metathesis of MI2 and the potassium salts of the β-diketiminato ligands, resulted in low volatility partially substituted Cax(tBuNC(CH3)CHC(CH3)NtBu)y(I)z compounds.
Ca(tBuNC(CH3)CHC(CH3)NtBu)2 is metallocene-type structure with η5-β-diketiminato ligands subliming rapidly (<1 h on a 1.0 g scale) without decomposition at 115°C/ 0.1 torr (demonstrating that this complex has high volatility).
Ca(iPrNC(CH3)CHC(CH3)NiPr)2 exhibits η2-β-diketiminato ligands, it sublimes at 135°C/0.1 torr, but the sublimation rate is significantly slower than for Ca(tBuNC(CH3)CHC(CH3)NtBu)2. [[i]]
[i] Organometallics 2004, 23, 4995-5002.