Trifluoroacetylacetonate rhodium(III) methyl complexes, cis-[Rh(TFA)(PPh 3) 2(CH 3)(L)][BPh 4] and cis-[Rh(TFA)(PPh 3) 2(CH 3)(I)] (L = CH 3CN, NH 3, pyridine), in comparison with their acetylacetonate analogs

Abstract

The oxidative addition of CH 3I to planar rhodium(I) complex [Rh(TFA)(PPh 3) 2] in acetonitrile (TFA is trifluoroacetylacetonate) leads to the formation of cationic, cis-[Rh(TFA)(PPh 3) 2(CH 3)(CH 3CN)][BPh 4] ( 1), or neutral, cis-[Rh(TFA)(PPh 3) 2(CH 3)(I)] ( 4), rhodium(III) methyl complexes depending on the reaction conditions. 1 reacts readily with NH 3 and pyridine to form cationic complexes, cis-[Rh(TFA)(PPh 3) 2(CH 3)(NH 3)][BPh 4] ( 2) and cis-[Rh(TFA)(PPh 3) 2(CH 3)(Py)][BPh 4] ( 3), respectively. Acetylacetonate methyl complex of rhodium(III), cis-[Rh(Acac)(PPh 3) 2(CH 3)(I)] ( 5), was obtained by the action of NaI on cis-[Rh(Acac)(PPh 3) 2(CH 3)(CH 3CN)][BPh 4] in acetone at −15 °C. Complexes 1–5 were characterized by elemental analysis, 31P{ 1H}, 1H and 19F NMR. For complexes 2, 3, 4 conductivity data in acetone solutions are reported. The crystal structures of 2 and 3 were determined. NMR parameters of 1–5 and related complexes are discussed from the viewpoint of their isomerism.