Thermal Design of a Schiff Base Cobalt(II) Precursor: Thermal Stability, Volatility, and Thin Film Deposition of Nanocrystalline Co ₃ O ₄ by Plasma‐Assisted MOCVD

ABSTRACT Bis(N‐1,1‐dimethylpropyl‐3‐methoxysalicylaldimine)cobalt(II) ( B ) is a square‐planar cobalt complex synthesized by reacting n‐tert‐pentylamine with its parent compound, bis(3‐methoxysalicylaldehydato)cobalt(II) ( A ), in a solution of methanol. The solid‐state Schiff base complex B was analyzed using TG/DTA in an inert nitrogen (N 2 ) atmosphere under atmospheric pressure. Complex A was determined to be nonvolatile, leaving 30% residue up to 598°C. In contrast, Complex B was fully volatile, with only 2% residue remaining at 325°C, following a single weight loss step. The condensation of n‐tert‐pentylamine with Complex A , replacing the aldehyde oxygen (‐CH=O) with an imine nitrogen (‐CH=N), resulted in a significant change in the volatility of Complex B . The volatile precursor B was characterized using FTIR spectroscopy, mass spectrometry, and elemental analysis such as carbon, nitrogen, and hydrogen. A transpiration TG method was utilized to examine the temperature dependence of the saturated vapor pressure and enthalpy of vaporization (∆ vap H o = 88.42 ± 0.05 kJ mol −1 ) of volatile complex B in the temperature range of 473–555 K. This molecule was used as a precursor to build a thin layer of cobalt oxide (Co 3 O 4 ) on a Si(100) substrate using plasma‐assisted metal–organic chemical vapor deposition. XRD, SEM/EDS, elemental mapping, and XPS were utilized to examine the nanocrystalline Co 3 O 4 thin films. The optical band gap was evaluated to be 2.29 eV based on analysis using the Kubelka–Munk function.