Preparation, characterization and reactivity of trifluoromethoxy palladium(ii) complexes

Abstract

The preparation of the first nitrogen- or phosphine-ligated trifluoromethoxylated Pd(II) complexes [(L)Pd(4-CF₃Ph)(OCF₃)] (L = TMEDA, 4-mepyridine or ^tBu-BrettPhos, BrettPhos, RuPhos and CPhos) was described. These complexes were extensively characterized in the solid state and in solution, and the structures of the complexes were further confirmed by high resolution X-ray crystallography of the single crystals of complexes 2a/b and 5a. Thermolysis of complexes [(L)Pd(4-CF₃Ph)(OCF₃)] (^tBu-BrettPhos, BrettPhos, RuPhos and CPhos) were explored but failed to give ArOCF₃. DFT calculations showed that the barrier for a concerted Ar-OCF₃ bond-forming reductive elimination from [(aryl)Pd(OCF₃)] complexes 5 is much higher than that of the competitive β-fluorine elimination process.