Thermal fluorine atoms, experimental

Table I) are virtually planar with no atom displaced by more than 0.08 A from the least-squares plane defined by those six atoms. The dihedral angle between the plane formed by the six coordinated carbon atoms (Plane II) and that formed by the uncoordinated olefin (Plane III) are also identical (117°), within experimental error, in all three complexes (Table I). The longest C—F bond distances in 56a and 56b are those on the terminal ends of the coordinated triene, reflecting the considerable rehybridization toward pyramidal geometry at these carbon atoms. Surprisingly, the overall skeletal structure of 57b is not significantly different from those of the fluorinated analogues 56, and the observed differences in air and thermal stability are not manifested in significantly different Mn—C bond distances or in a different mode of metal-ligand bonding in 57b.

In the present work we have sought to resolve this discrepancy based upon new experimental results and to provide a critique of the nuclear recoil technique for the investigation of thermal hydrogen abstraction reactions by atomic fluorine. 

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