Three new O,N-coordinated Ni(II) complexes: Syntheses, crystal structures, and MOCVD applications

•We synthesized the Ni(II) complexes with coordination number 4 and 6.•We modified the synthetic technique of Schiff base Ni complex.•The structures and thermal properties of complexes were investigated.•Two Ni chelates were tested in MOCVD process.•The Ni and Ni3C films were deposited from these complexes.

Three new O,N-coordinated nickel (II) complexes, namely, Ni(dmpda(acac)2) (1), Ni(pda)(acac)2 (2) and Ni(pda)(tfac)2 (3) have been synthesized ((dmpda(acac)2 – N,N′-(2,2-dimethyl-1,3-diaminopropane)-bis-(2,4-pentanedioniminoato(2-), acac – 2,4-pentanedionato(−), pda – 1,3-diaminopropane, tfac – 1,1,1-trifluoroacetylacetonato(−)) and tested as new precursors for metal–organic chemical vapor deposition (MOCVD). The structures of 1–3 were determined by single-crystal X-ray diffraction (XRD) and further characterized by IR and Raman spectroscopies. All three compounds crystallize in the triclinic space group P  1¯ with unit cell parameters of a = 9.0294(6), b = 9.2879(6), c = 10.4065(6) Å, α = 74.855(3), β = 68.717(3), γ = 78.708(3) for 1; a = 7.6947(2), b = 10.3087(3), c = 10.7144(3) Å, α = 101.784(1), β = 95.367 (1), γ = 106.134(1) for 2; and a = 7.8931(5), b = 10.8803(8), c = 10.9438(7) Å, α = 103.283(2), β = 97.070(3), γ = 103.050(2) for 3. The density functional theory (B3LYP) quantum chemical calculations have been used for detailed assignment of all intense bands in the vibrational spectra of the compounds studied. Thermal gravimetric analysis (TG/DTA) has shown that the species 1 and 3 sublime almost without decomposition, and 2 decomposes to some extent. MOCVD test experiments were carried out at low pressure (10 Torr) using 1 and 3 as precursors on Ta/Si substrates. The films have been characterized by X-ray powder diffraction, scanning electron microscopy, and energy dispersive spectroscopy were found to be primarily composed either of fcc-Ni or Ni3C phases. The phase composition of the films strongly depends on the MOCVD conditions.

Graphical abstractThree Ni(II) complexes have been synthesized for the first time. Two compounds turned out to be suitable for MOCVD applications. The single-phase fcc-Ni films can be deposited on Ta/Si substrates. The obtained data are useful for further optimization of deposition conditions of fcc-Ni films with required composition and morphology.Figure optionsDownload full-size imageDownload as PowerPoint slide