Monomeric Iron Heteroarylalkenolates: Structural Design Concepts and Investigations on Their Application in Chemical Vapor Deposition

Aryl substituted β-alkenol 1-(dimethyl-1,3-thiazol-2-yl)-3,3,3-trifluoropropenol (DMTTFP) was employed as an efficient metal chelator to obtain volatile monomeric precursors containing Fe^II and Fe^III centers. [Fe­(DMTTFP)₂] (1) and [Fe­(DMTTFP)₂­(OBu^t)] (2) were synthesized by reacting suitable starting materials with DMTTFP. The molecular structures were elucidated by single-crystal X-ray diffraction analyses, which revealed a distorted tetrahedral and a trigonal-bipyramidal arrangement of ligands around iron atoms in 1 and 2, respectively. Magnetic investigations confirmed [Fe­(DMTTFP)₂] to exhibit a thermally populated spin-state transition that becomes apparent below 10 K. The high-spin state was gradually transferred to a low-spin state on cooling, suggesting a nonmagnetic ground state. [Fe­(DMTTFP)₂­(OBu^t)] exhibited enhanced stability, sufficient volatility, and decomposition behavior serving as an efficient Fe^III precursor for the growth of iron oxide layers on an Al₂O₃ substrate via chemical vapor deposition.