Molecular Co(II) and Co(III) Heteroarylalkenolates as Efficient Precursors for Chemical Vapor Deposition of Co₃O₄ Nanowires

Abstract

Two new cobalt precursors, Co(II)(PyCHCOCF3)2(DMAP)2 (1) and Co(III)(PyCHCOCF3)3 (2), based on Co(II) and Co(III) centers were synthesized using a redox active ligand system. The different chemical configurations of 1 and 2 and differential valence states of cobalt were confirmed by crystal structure determination and comprehensive analytical studies. Whereas 1 could not be studied by NMR due to the paramagnetic nature of the central atom, 2 was unambiguously characterized by multinuclear 1D and 2D NMR experiments in solution. Both compounds are efficient precursors for catalyst-free growth of Co3O4 nanowires on Si and Al2O3 substrates by a chemical vapor deposition process. The different valence states of cobalt species influenced their chemical decomposition pathways in the gas phase; for instance, 1 was partially oxidized (Co(2+) → Co(3+)), and 2 underwent reduction (Co(3+) → Co(2+)) to form pure cobaltite in both cases that verified the metal-ligand redox interplay. Co3O4 nanowires with nanometric diameters (50-100 nm) were obtained irrespective of the chosen cobalt precursor. Investigations on the humidity sensing behavior of CVD deposits demonstrated their potential as promising sensor materials.

Selective Synthesis and Thermodynamic Relations of Polymorphic Co(NCS)2‐4‐Dimethylaminopyridine Coordination Compounds

“…It is noted, that no crystal structures with Co(NCS) 2 and DMAP are reported in the CCDC database but some discrete complexes with other transition metal cations are known . However, for compounds with other anions in which Co is coordinated by DMAP, more octahedral than tetrahedral compounds are known . It is also noted that a 1 D compound is reported, in which Co cations are linked by pairs of azido ligands into chains, an arrangement that exactly corresponds to that what we expected for thiocyanate coordination polymers and which indicates that also with Co(NCS) 2 the desired chain compound might be available .…”

Molecular Level Synthesis of InFeO3 and InFeO3/Fe2O3 Nanocomposites

“…Attempts directed to obtain “donor-free” indium–iron complexes with 1:1 ratio were not successful, possibly due to the structural preferences observed in 2 and 3 . The incorporation of the anionic ligand HPyTFP, which has been used for stabilizing a large number of metals through its bidentate chelation, was found to increase the stability of the heterometallic framework based on the 1:1 ratio between In and Fe which resulted in the formation of 1 . ,− The chelating ligand is coordinated to the indium metal center due to the larger ionic radius of indium . However, the use of chelating ligands in the construction of heterometallic alkoxides represents a delicate interplay between the driving force for the formation of mixed metal assemblies and the stabilization of monometallic species.…”

A Study on Oxygen Evolution Activity of Co3O4with different morphology prepared by Ultrasonic Spray Pyrolysis for Water Electrolysis

“…특히, 산소발생반응에서는 수소발생반응에 비해 높은 과전압을 요구하며 [14][15][16][17] [34][35][36], 전 기도금법 [37,38], 열분해법 [39][40][41], 화학증착법 [42,43] …”