Volatility and High Thermal Stability in Mid-to-Late First-Row Transition-Metal Complexes Containing 1,2,5-Triazapentadienyl Ligands

Treatment of first-row transition-metal MCl2 (M = Ni, Co, Fe, Mn, Cr) with 2 equiv of the potassium 1,2,5-triazapentadienyl salts K(tBuNNCHCHNR) (R = tBu, NMe2) afforded M(tBuNNCHCHNR)2 in 18–73% isolated yields after sublimation. The X-ray crystal structures of these compounds show monomeric, tetrahedral molecular geometries, and magnetic moment measurements are consistent with high-spin electronic configurations. Complexes with R = tBu sublime between 155 and 175 °C at 0.05 Torr and have decomposition temperatures that range from 280 to 310 °C, whereas complexes with R = NMe2 sublime at 105 °C at 0.05 Torr but decompose between 181 and 225 °C. This work offers new nitrogen-rich ligands that are related to widely used β-diketiminate and 1,3,5-triazapentadienyl ligands and demonstrates new complexes with properties suitable for use in atomic-layer deposition.