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Oxidative addition of perfluorobenzyl iodide to [M(η 5 -C 5 R 5 )(CO) 2 ] (M ) Co, R ) H, Me; M ) Rh, R ) Me) in benzene affords the perfluorobenzyl complexes 2b)). Further reaction of 1a or 2a with PMe 3 in benzene results in a substitution reaction to give complexes [Co(η 5 -C 5 R 5 )-(CF 2 C 6 F 5 )I(PMe 3 )] (R ) H (3a), Me (4a)) . While the reaction of (pentamethylcyclopentadienyl)cobalt complex 2a with PMe 3 in benzene gives 4a, the analogous reaction in THF results in alkyl C-H activation and aryl C-F activation, with coupling of the pentamethylcyclopentadienyl ligand and the perfluorobenzyl ligand, to give 9a. Similarly, the reaction of 2a with PMe 2 Ph in THF affords the analogous ring-coupled complex 9b, while reaction of the cyclopentadienyl analogue 1a with PMe 2 Ph affords the simple substitution product 5a. In contrast to the reactions of the (pentamethylcyclopentadienyl)cobalt complexes, reaction of the rhodium analogue 2b with PMe 3 or PMe 2 Ph result in a simple substitution to give [Rh(η 5 -C 5 Me 5 )(CF 2 C 6 F 5 )I(L)] (L ) PMe 3 (5a) PMe 2 Ph (5b)). Attempts to purify complexes 9 result in facile hydrolysis of the CF 2 group to give acyl complexes 10. A mechanism is proposed for this coupling reaction, and an analogue 13 of a proposed cationic intermediate has been isolated and shown to react with iodide to afford 10, via 9a. Heating of 2a results in a different coupling reaction to afford the organic cyclopentadiene 14. The solid state structures of 3a, 5b, and 10b were determined by X-ray crystallography.a Quantity minimized ) ∑w∆ 2 ; R ) ∑∆/∑(Fo); R(w) ) ∑∆w 1/2 /∑(Fo‚w 1/2 ), ∆ ) |(Fo -Fc)|

Attempts to prepare fluoroalkyl(hydrido) complexes of iridium by reactions of [Ir(C5Me5)(PMe3)(RF)I] {RF = CF2CF2CF3, CF(CF3)2} with either NaBH4 or LiAlH4 afford (inter alia) iridium hydrides [Ir(C5Me5)(PMe3)(CHCFCF3)H] or [Ir(C5Me5)(PMe3)(C{CF3}CF2)H], in which the fluoroalkyl groups are converted to unsaturated ligands via apparent α-CF activation and elimination of HF. A clean and selective route to desired saturated fluoroalkyl(hydrido) complexes [Ir(C5Me5)(PMe3)(RF)H] {RF = CF2CF2CF3, CF2CF3, CF(CF3)2} is afforded by treatment of the aqua cations [Ir(C5Me5)(PMe3)(RF)(H2O)]BF4 with 1,8-bis(dimethylamino)naphthalene (“Proton Sponge”). The reaction also affords the corresponding rhodium analogue [Rh(C5Me5)(PMe3)(CF2CF2CF3)H] from the corresponding aqua precursor. The source of the hydride is unambiguously defined as an N−CH3 group by using the perdeuteromethylated analogue of Proton Sponge, which provides clean routes to the corresponding fluoroalkyl(deutero) complexes of iridium. Triethylamine or cobaltocene also effect this reaction, though not as cleanly as Proton Sponge. The mechanism of this novel transformation is discussed. The fluoroalkyl(hydrido) complexes are thermally robust, but do react with chlorinated solvents to give the corresponding chlorides. Single-crystal X-ray diffraction studies of the structures of [Ir(C5Me5)(PMe3)(CF2CF2CF3)H], [Rh(C5Me5)(PMe3)(CF2CF2CF3)H], and [Rh(C5Me5)(PMe3)(CF2CF2CF3)Cl] are reported and compared.