Orthometalation reactions in trifluoroacetate dirhodium(II) compounds. Molecular structure of Rh 2(O 2CCF 3) 2[(C 6H 4)PPh 2] 2·(PPh 3) 2·2(C 7H 8)

Abstract

Rh 2(O 2CCF 3) 3[(C 6H 4)PPh 2]·(HO 2CCF 3) 2 reacts with PPh 3 yielding the doubly metalated compound Rh 2(O 2CCH 3) 2− [(C 6H 4)PPh 2] 2·(HO 2CCF 3) 2. The reaction proceeds via a reactive intermediate with an equatorial phosphine, Rh 2(η 2-O 2CCF 3)(μ-O 2CCF 3) 2[(C 6H 4)PPh 2](PPh 3)·(HO 2CCF 3), which can also be generated in moderate yield under photochemical conditions. The structure of the PPh 3 bis-adduct Rh 2(O 2CCF 3) 2[(C 6H 4)PPh 2] 2·(PPh 3) 2·2(C 7H 8) has been determined by X-ray diffraction. M r=1663.27, orthorhombic, space group Fdd2, a=41.748(9), b=21.620(5), c=17.375(5) Å, V=15683(6) Å 3, Z=8, D x=1.41 g cm −3. Mo Kα radiation (graphite crystal monochromator, λ=0.71073 Å), μ(Mo Kα)=5.57 cm −1, F(000)=6800, T=293 K. Final conventional R factor=0.035 for 2789 ‘observed’ reflections and 422 variables. The molecule shows crystallographic two-fold axis symmetry through the RhRh bond. One toluene solvent molecule slightly disordered is present in the asymmetric unit.