Synthesis of the First Family of Rhodium(I) Perfluoroalkyl Complexes from Rhodium(I) Fluoro Complexes¹

Abstract

The rhodium(I) fluoro complexes [RhF(COD)(PR3)] (R = Ph (1a), C6H4OMe-4 (1b), i-Pr (1d), Cy (1e); COD = 1,5-cyclooctadiene) react with Me3SiRF to afford the rhodium(I) perfluoroalkyl complexes [Rh(RF)(COD)(PR3)] (RF = CF3, R = Ph (2a), C6H4OMe-4 (2b), i-Pr (2d), Cy (2e); RF = n-C3F7, R = Ph (2c)), of which 2a,c were isolated as pure solids. [Rh(CF3)(NBD)(PPh3)] (3) was prepared by reaction of 2a with norbornadiene. The reactions of 2a−c with 2,6-dimethylphenyl isocyanide (XyNC) or t-BuNC, in a 1:2 molar ratio, gave the compounds trans-[Rh(RF)(CNR')2(PR3)] (RF = CF3, R' = Xy, R = Ph (4a), C6H4OMe-4 (4b); RF = CF3, R' = t-Bu, R = Ph (4a'); RF = n-C3F7, R' = Xy, R = Ph (4c)). The reactions of 2a−c with an equimolar amount of XyNC gave mixtures containing complexes 4a−c as the major products. The peroxo complexes [Rh(CF3)(η2-O2)(CNXy)2(PR3)], (R = Ph (7a), C6H4OMe-4 (7b)) were isolated by reacting O2 with 4a,b, respectively. The complexes [Rh(RF)(CNR')3(PR3)] (RF = CF3, R' = Xy, R = Ph (8a), C6H4OMe-4 (8b); RF = n-C3F7, R' = Xy, R = Ph (8c)) were obtained by reaction of 2a−c with 3 equiv of XyNC. Formation of [Rh(CF3)(PPh3)(CO)3] (9) in the reaction of complex 2a with CO was spectroscopically observed. The crystal structures of complexes 4a, 7a, and 8a have been determined by single-crystal X-ray diffraction studies. The dynamic behavior in solution of the prepared complexes was studied by variable-temperature NMR.