LAUSR

Perfluorination of one η5-C5H5 ring in the MC10H10 system (M = Ni, Pd, Pt) to give an MC10H5F5 system greatly destabilizes structures containing a perfluorinated pentahapto η5-C5F5 ring. As a result, the metallapentafluorobenzene structures (η5-C5H5)(MC5F5) are the lowest energy structures for all three metals with energy differences of 1.4, 6.2, and 16.2 kcal/mol for nickel, palladium, and platinum, respectively. In addition, for palladium and platinum isomeric metalla-tetrafluorocyclopentadiene structures with a complexed fluorobenzene ring, i. e., (C6H5F)(MC4F4) (M = Pd, Pt), are lower energy structures than the lowest energy metallocene structures. Furthermore, for palladium and platinum the lowest energy metallocene structures are slipped metallocenes with a trihapto rather than a pentahapto pentafluorocyclopentadienyl ring. These theoretical results suggest the pentafluoro¬cyclopentadienyl anion as a reagent for synthesizing metallapentafluoro-benzene derivatives by reactions with (η5-C5R5)M(CO)X, (η5-C5R5)2M2(µ-CO)2, or (η5-C5R5)2Ni (R = H, Me; M = Ni, Pt).