Barium β-DIKETIMINATES
π-β-diketiminato ligands, considering their large steric hindrance , have been studied as possible ligands that might lead to volatile, oxygen-free Ca, Sr and Ba complexes. [[i]]
Alkaline earth (including Ba) bis-β-diketiminates were prepared by protonolysis reactions using M(N(SiMe3)2)2(THF)2. The attempted preparation route by metathesis of MI2 and the potassium salts of the β-diketiminato ligands, resulted in partially substituted Mx(tBuNC(CH3)CHC(CH3)NtBu)y(I)z complexes having low volatility.
[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”
Barium bis-(tert-butyl)diketiminate Ba(tBuNC(CH3)CHC(CH3)NtBu)2
Ba(tBuNC(CH3)CHC(CH3)NtBu)2 is metallocene-type structures with η5-β-diketiminato ligands, which sublime rapidly (<1 h on a 1.0 g scale) without decomposition 150 (Ba) °C (0.1 torr). This is an extremely low Itoesium bis(tetrahydridoboraste)sublimation temperature for a Ba complex, and indicates an unusually high vapor pressure.
Ba(tBuNC(CH3)CHC(CH3)NtBu)2, has been tested as precursor for BaTiO3 film deposition (Prof. David G. Goodwin, California Institute of Technology) [[i]]
[i] Organometallics 2004, 23, 4995-5002.
Barium bis-(iso-propyl)diketiminate Ba(iPrNC(CH3)CHC(CH3)NiPr)2
Barium complex {Ba(iPrNC(CH3)CHC(CH3)NiPr)2}2 adopts an unusual dimeric structure with bridging η5-β-diketiminato ligands. {Ba(iPrNC(CH3)CHC(CH3)NiPr)2}2 sublimes at 180 °C (0.1 torr), the rates of sublimation are significantly slower than for Ba(tBuNC(CH3)CHC(CH3)NtBu)2. [16]