Thermal Decomposition of Fluoroalkyl Pentacarbonylmanganese(I) Derivatives by α-Fluorine Elimination

This contribution brings to light the first example of an α-F elimination process in manganese organometallic chemistry. As shown in a recent contribution ( Chem. Eur. J., DOI: 10.1002/chem.201804007) the thermal decomposition of compounds [Mn(RF)(CO)5] (RF = CF3, 1; CHF2, 2; CH2CF3, 3) in C6D6 at 70–100 °C leads primarily to homolytic Mn–RF bond cleavage, followed by RF• trapping in the presence of (Me3Si)3SiH (TTMSS) to yield RF–H. However, the formation of other products was revealed by a detailed 19F NMR investigation. Compounds 1 and 2 also produced significant amounts of (Me3Si)3SiF and of F-poorer organic compounds (namely, CH2F2 and CH3F from 1; CH3F from 2). The extent of this additional process was rather important (67%) for 1 but minor (10%) for 2. In contrast, no traces of either (Me3Si)3SiF or CH3CHF2 were detected during the decomposition of 3. A DFT investigation shows that the process occurs via CO dissociation followed by α-F elimination from [Mn(RF)(CO)4] to yield [cis-MnF(CXF)(CO)4] (X ...