Nickel-based
nanostructured materials have gained widespread attention,
particularly for energy-related applications. Employing chemical vapor
deposition (CVD) for NiO necessitates suitable nickel precursors that
are volatile and stable. Herein, we report the synthesis and characterization
of a series of new nickel β-ketoiminato complexes with different
aliphatic and etheric side chain substitutions, namely, bis(4-(isopropylamino)-pent-3-en-2-onato)nickel(II)
([Ni(ipki)2], 1), bis(4-(2-methoxyethylamino)pent-3-en-2-onato)nickel(II)
([Ni(meki)2], 2), bis(4-(2-ethoxyethylamino)pent-3-en-2-onato)nickel(II)
([Ni(eeki)2], 3), bis(4-(3-methoxy-propylamino)-pent-3-en-2-onato)nickel(II)
([Ni(mpki)2], 4), and bis(4-(3-ethoxypropylamino)pent-3-en-2-onato)nickel(II)
([Ni(epki)2], 5). These compounds have been
thoroughly characterized with regard to their purity and identity
by means of nuclear magnetic resonance spectroscopy (NMR) and electron
impact mass spectrometry (EI-MS). Contrary to other transition metal
β-ketoiminates, the imino side chain strongly influences the
structural geometry of the complexes, which was ascertained via single-crystal
X-ray diffraction (XRD). As a result, the magnetic momenta of the
molecules also differ significantly as evidenced by the magnetic susceptibility
measurements employing Evan’s NMR method in solution. Thermal
analysis revealed the suitability of these compounds as new class
of precursors for CVD of Ni containing materials. As a representative
precursor, compound 2 was evaluated for the CVD of NiO
thin films on Si(100) and conductive glass substrates. The as-deposited
nanostructured layers were stoichiometric and phase pure NiO as confirmed
by XRD, Rutherford backscattering spectrometry (RBS), and nuclear
reaction analysis (NRA). X-ray photoelectron spectroscopy (XPS) indicated
the formation of slightly oxygen-rich surfaces. The assessment of
NiO films in electrocatalysis revealed promising activity for the
oxygen evolution reactions (OER). The current densities of 10 mA cm–2 achieved at overpotentials ranging between 0.48 and
0.52 V highlight the suitability of the new Ni complexes in CVD processes
for the fabrication of thin film electrocatalysts.