(BICYCLO[2.2.1]HEPTA-2,5-DIENE)[1,4-BIS(DIPHENYLPHOSPHINO)BUTANE]RHODIUM(I) TETRAFLUOROBORATE

synthetischea solution of [Rh(nbd)acac] in THF is treated with fluoroboric acid, followed by addition of 1,4-bis(diphenylphosphino)butane (dppb). The solution becomes deep red and ether is added to precipitate the catalyst, which is then isolated by filtration. The unpurified product is generally adequately pure for most applications. Recrystallization from methanol can be performed to obtain orange needles of [Rh(nbd)(dppb)]BF4. Although air-sensitive in solution, the crystalline complex is indefinitely stable when prepared pure and stored under N2 or Ar below 0 °C. A convenient preparation of the corresponding trifluoromethanesulfonate has been described. The cyclooctadiene (cod) analog has been characterized by X-ray crystallography, and the dynamic solution structure of related systems has been studied by multinuclear NMR techniques.