Photochemical reactions of [Re(η5-C5R5)(CO)3] (R = H or Me) with partially fluorinated benzenes:: C-H and C-F activation

UV Irradiation of [Re(eta(5)-C5R5)(CO)(3)] (R=Me or H) in the presence of C6F5H or 1,2,4,5-C6F4H2 effected intramolecular C-H activation, generating the hydrido complexes trans-[Re(eta(5)-C5R5)(CO)(2)(Ar)(F)H] [(Ar)(F)=C6F5 or 2,3,5,6-C6F4H] as the principal photochemical products. The identities of the hydrido complexes were confirmed by independent thermal syntheses. The photoreaction of [Re(eta(5)-C5Me5)(CO)(3)] with C6F5H also generated the fulvene complex [Re(eta(6)-C5Me4CH2)(CO)(2)(C6F5)] 2a and two bis(aryl) derivatives: cis-[Re(eta(5)-C5Me5)(CO)(2)(C6F5)(2)] 3a and [Re(eta(5)-C5Me5)(CO)(2)(C6F5)(2,3,5,6-C6F4H)] 4a in low yield. Complex 2a results from an intramolecular C-H activation, while 3a and 4a derive from a C-H and a C-F activation of a second molecule of pentafluorobenzene, respectively. The origin of the minor products was elucidated by showing that UV irradiation of [Re(eta(5)-C5Me5)(CO)(2)(C6F5)H] in C6F5H produces 2a, 3a and 4a, while photolysis of 2a produces only 3a. The reaction of [Re(eta(5)-C5Me5)(CO)(3)] with 1,2,4,5-C6F4H2 gave analogues 2b and 4b as minor products. The photoreaction of [Re(eta(5)-C5H5)(CO)(3)] in C6F5H or 1,2,4,5-C6F4H2 generated bis(aryl) compounds and the unusual binuclear complexes [Re-2(eta(5)-C5H5)(mu-eta(1):eta(5)-C5H4)(CO)(4)(Ar)(F)] as the minor products. The binuclear complex with (Ar)(F)=2,3,5,6-C6F4H has been characterized by X-ray crystallography. The Re-Re bond [3.0258(7) Angstrom] is close to collinear with the Re-C (aryl) bond. One {Re(CO)(2)} unit is twisted by about 73.0 degrees with respect to the other.