Synthesis of rhodium complexes with novel perfluoroalkyl substituted cyclopentadienyl ligands

Mixtures of isomers of (perfluoroalkyl)tetramethylcyclopenta-1,3-dienes (CH 3)(4)C5H(CF2)(n)CF3 (n = 3, 5, 7, 9) were synthesized as precursors of new cyclopentadienyl ligands for organotransition metal catalysis in fluorous b iphase media and characterized by combination of GC-MS and C-13 NMR spectro scopy. Rhodium(III) chloro complexes [Rh{(CH3)(4)C-5(CF2)(n)CF3}Cl-2](2) an d rhodium(I) carbonyl complexes [Rh{(CH3)(4)C-5(CF2)(n)CF3}(CO)(2)] were pr epared from the cyclopentadienes and molecular structure of [Rh{(CH3)(4)C-5 (CF2)(5)CF3}Cl-2](2) was determined by X-ray diffraction. The ligands are e lectronically close to the unsubstituted cyclopentadienyl as shown by value s of carbonyl stretching frequencies in the carbonyl complexes. Neither car bonyl frequencies nor NMR chemical shifts of the complexes are substantiall y affected by the length of the perfluoroalkyl chain.