SYNTHESIS AND SUBSEQUENT REARRANGEMENT OF CHLORO(PENTAFLUOROPHENYL)-1,5-CYCLOOCTADIENEPALLADIUM(II), AN ILLUSTRATIVE EXAMPLE OF ENDO ATTACK TO A COORDINATED DOUBLE-BOND

Pd(C6F5)Cl(1,5-cyclooctadiene) has been prepared in high yield and characterized crystallographically: monoclinic space group P21/c, a = 8.313 (1) Å, b = 7.7800 (6) Å, c = 22.292 (4) Å, β = 95.77 (1)° (Z = 4), final R of 0.024 for 2080 independent reflections. The X-ray structure reveals a high trans influence of the C6F5 groups that weakens the opposite palladium-olefin bond. This complex rearranges slowly in solution by intramolecular double bond insertion into the Pd-C6F5 bond to give an allyl complex Pd2(μ-Cl)2(6-C6F5-1-3-η3-C8H12)2 and σ, π complex Pd2(μ-Cl)2(8-C6F5-l:4-5-η3-C8H12)2. A derivative of the latter, Pd(8-C6F5-l:4-5-η3)-C8H12)(F6-acac), has been characterized crystallographically: triclinic space group Pī, a= 10.360 (3) Å, b= 11.051 (2) Å, c = 11.084 (4) Å, α = 73.70 (2)°, β = 61.41 (2)°, γ = 66.08 (2)°, final R of 0.036 for 3341 independent reflections. The rearrangement of Pd(C6F5)Cl(1,5-COD) is catalyzed by its products and slowed down in coordinating solvents. Both products are the result of an endo attack of C6F5 to COD and are formed competitively from a common intermediate. © 1990, American Chemical Society. All rights reserved.