Synthesis of rhodium(i) and rhodium(iii) perfluoroalkyl complexes from [Rh(μ-OH)(COD)]2

Abstract

Complexes [Rh(R_F)(PMe_xPh_3−x)₃] (R_F = CF₃, x = 1 (2); R_F = n-C₃F₇, x = 1 (3), x = 2 (4)) are quantitatively generated in situ when [Rh(μ-OH)(COD)]₂ (1) is reacted with the corresponding Me₃SiR_F and PMe_xPh_3−x. In contrast, the reaction of 1 with Me₃SiCF₃ and PMe₂Ph gives mixtures containing [Rh(CF₃)(PMe₂Ph)₃] (5), [Rh(CF₃)(PMe₂Ph)₄] (6), [Rh(CF₃)(COD)(PMe₂Ph)₂] (7) and [Rh(CF₃)(COD)(PMe₂Ph)] (8), the relative amounts of which depend on the Rh:PMe₂Ph molar ratio. [Rh(CF₃)(η²-O₂)(PMePh₂)₃] (9) was isolated after bubbling air through a solution of 2 in THF. Reactions of in situ generated 2–5 with L = CO, XyNC (Xy = 2,6-dimethylphenyl) gives pentacoordinate complexes [Rh(R_F)L(PMe_xPh_3−x)₃] (L = CO, x = 1, R_F = CF₃ (10), n-C₃F₇ (11); L = XyNC, R_F = CF₃, x = 1 (12), 2 (13); L = XyNC, R_F = n-C₃F₇, x = 2 (14)). Oxidative addition of MeI (i) to 2 gives (PMe₂Ph₂)[OC-6-43]-[Rh(CF₃)(Me)I₂(PMePh₂)₂] (15), which reacts with Tl(acac) (acac = acetylacetonato) to give [OC-6-14]-[Rh(CF₃)(Me)(acac)(PMePh₂)₂] (16), (ii) to 5 gives [Rh(CF₃)(Me)I(PMe₂Ph)₃] as a ca. 5 : 1 mixture of the isomers OC-6-34 (17) and OC-6-43 (17′), and (iii) to 12 or 14 leads to [OC-6-52]-[Rh(CF₃)(Me)I(CNXy)(PMePh₂)₂] (18) or [OC-6-52]-[Rh(n-C₃F₇)(Me)I(CNXy)(PMe₂Ph)₂] (19), respectively. Oxidative addition of iodotrifluoroethene to 12 affords [OC-6-32]-[Rh(CFCF₂)(CF₃)I(CNXy)(PMePh₂)₂] (20). The crystal structures of 10, 15 and 19 were determined.