SYNTHESIS AND REACTIONS OF THE RHENIUM FULVENE COMPLEXES [RE(ETA(6)-C5ME4CH2)(CO)(2)(C6F4R)] (R = F OR CF3) - PRODUCTS DERIVED FROM INITIALC-F ACTIVATION

The UV irradiation of [Re(eta(5)-C5Me5)(CO)(3)] in the presence of C6F 6 effected intermolecular C-F and intramolecular C-H activation genera ting [Re(eta(6)-C5Me4CH2)(CO)(2)(C6F5)] 1a in two isomeric forms. In t he major isomer the CH2 group lies trans to the C6F5 group both in sol ution and in the crystal. In the minor isomer the CH2 lies cis to the C6F5 group. A similar reaction with C6F5CF3 generates [Re(eta(6)-C5Me4 CH2)(CO)(2)(C6F4CF3)] 1b in four isomeric forms. In the major form the CF3 group is in the 4 position and the CH2 group lies trans to the C6 F4CF3 group. The other three isomers are formed by rotation of the eta (6)-C5Me4CH2 ligand as above, by placing the CF3 at the 3 position, an d by a combination of the two. Complex 1a reacted with PMe3 to form th e zwitterionic complex [Re(eta(5)-C5Me4CH2PMe3)(CO)(2)(C6F5)] and with MeO- to form the anion [Re(eta(5)-C5Me4CH2OMe)(CO)(2)(C6F5)](-), isol able as the NEt4+ salt. The reaction of 1a with HX (X = Cl or Br) gene rated cis-[Re(eta(5)-C5Me5)(CO)(2)(C6F5)X] initially. More prolonged r eaction led to the trans isomers. On reaction with III, only the trans isomer was formed. Reaction of la with HBF4 in Et2O in the presence o f MeCN led to formation of the salt [Re(eta(5)-C5Me5)(CO)(2)(C6F5)(NCM e)](+)[BF4](-). The halogens Cl-2, Br-2 and I-2 reacted to form (halog enomethyl)tetramethylcyclopentadienyl complexes trans-[Re(eta(5)-C5Me4 CH2X)(CO)(2)(C6F5)X] (X = Cl, Br or I). The bromo complex has been cha racterized crystallographically.