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

Abstract

Treatment of first-row transition-metal MCl(2) (M = Ni, Co, Fe, Mn, Cr) with 2 equiv of the potassium 1,2,5-triazapentadienyl salts K(tBuNNCHCHNR) (R = tBu, NMe(2)) 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 = NMe(2) 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.

Synthesis, Structure, and Solution Reduction Reactions of Volatile and Thermally Stable Mid to Late First Row Transition Metal Complexes Containing Hydrazonate Ligands

“…Additionally, M(Me 2 NNC(tBu)O) 2 have lower reactivities toward reducing coreagents than 2 and 4 to afford metal powders. The 1,2,5-triazapentadienyl complexes M(tBuNNCHCHNR) 2 (R = tBu or NMe 2 , M = Ni, Co, Fe, Mn, Cr) are monomeric for all metals, sublime at 105 °C (R = NMe 2 ) or between 155 and 175 °C (R = tBu) at 0.05 Torr, and have solid state decomposition points between 280 and 310 °C (R = tBu) and 181–225 °C (R = NMe 2 ) . Like 2 , Ni(tBuNNCHCHNNMe 2 ) 2 is reduced to nickel metal by anhydrous hydrazine in tetrahydrofuran at ambient temperature.…”

“…The thermal decomposition temperature of 6 (273 °C) is much higher than that of the widely promoted nickel(II) film growth precursor Ni(iPrNCMeNiPr) (180 °C) 40 and is similar to that of our recently reported complex Ni(tBuNNCHCHNtBu) 2 (290 °C). 41 High thermal stability is very important for ALD precursors, since the precursor thermal decomposition temperature is usually close to the temperature at which loss of selflimited ALD growth occurs and CVD-like growth ensues. 12,30 Interestingly, 6 melts below its sublimation temperature, and thus vapor transport occurs from the liquid state.…”

“…The 1,2,5-triazapentadienyl complexes M-(tBuNNCHCHNR) 2 (R = tBu or NMe 2 , M = Ni, Co, Fe, Mn, Cr) are monomeric for all metals, sublime at 105 °C (R = NMe 2 ) or between 155 and 175 °C (R = tBu) at 0.05 Torr, and have solid state decomposition points between 280 and 310 °C (R = tBu) and 181−225 °C (R = NMe 2 ). 41 Like 2, Ni(tBuNNCHCHNNMe 2 ) 2 is reduced to nickel metal by anhydrous hydrazine in tetrahydrofuran at ambient temperature. Complexes M(tBuNNCHCHNtBu) 2 have higher sublimation temperatures and similar decomposition temperatures, compared to 1−11, whereas M(tBuNNCHCHNNMe 2 ) 2 have similar sublimation temperatures to 6−11 but much lower decomposition temperatures.…”

Synthesis, Characterization, and Thermal Properties of N-alkyl β-Diketiminate Manganese Complexes

“…after parameter optimization. Significant advances have also been made by Winter − and Gordon , (Table ) in the development of designer ALD precursors, although these studies have primarily focused on growth of metallic films.…”

Zinc and aluminum complexes derived from 2, 4-N, N′-disubstituted 1, 3, 5-triazapentadienyl ligands: Synthesis, characterization and catalysis of the ring-opening polymerization of rac-lactide

“…Conjugated 5-membered π systems especially the nitrogen-containing ligands such as 1,5-diazapentadienyls [β-diketiminates] [1] and its nitrogen analogs 1,3,5-triazapentadienyls [2,3] not only provide a unique steric and electronic environment for stabilizing a vast array of main-group and transition metals, but allow facile tuning through substitution at the N atoms of the ligand backbone. The related 1,2,5-triazapentadienyls [4] and 1,2,4,5-tetraaza (known as "formazans") ligands have also been studied [5]. Their zinc and aluminum compounds and some other main group metal complexes have been used as catalysts in the polymerization reactions [6][7][8][9][10][11].…”