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Complexes of fluoroalicyclic derivatives of phosphorus

University of British Columbia

Dicyclohexyl phosphine reacts with ClC=CCl(CF₂) (n = 2,3,4) and [ClC=C(CF₂)₂]₂ in DMF to give the ditertiary phosphines (L-L) of formulae (C₆H₁₁)₂PC=CP(C₆H₁₁)₂ (CF₂) [sub n] (n = 2, 25a; n = 3, 25b) and (C₆H₁₁)₂PC=C (CF₂)₂]₂ (24) together with tertiary phosphines (L) of formulae, (C₆H₁₁)₂PC=CCl (CF₂)[sub n] (n = 2, 26a; n = 3, 26c; n = 4, 26e). The reactions of these new ligands and those of other ligands such as [(C₆H₅C₂)PC= (CF₂)₂]₂, 23 (L-L) and (C₆H₅)₂PC=CCl(CF₂)[sub n] (n = 2, 26b; n = 3, 26d; n = 4, 26f) (L) with a range of transition metal carbonyls and metal halides have been investigated. With Group VI metal hexacarbonyls the ditertiary phosphine ligands, 2_4_, 25a and 25b give the expected chelate (L-L) (M(CO)₄ (M = Cr,Mo,W) complexes, whereas the tertiary phosphines, 26a - 26f give the monodentate LM(CO)₅ complexes. Reactions with Pd(II) and Pt(II) halides give complexes of formulae (L-L)MCl₂, (L-L = 23, 24a, 25a; M = Pd(II), Pt(II)), L₂MCl₂ (L = 26a, 26b; M = Pd(II), Pt(II)) and L₂M₂Cl₄ (L = 26b, 26d; M = Pd(II)). A complex of formula, (L-L)₂Pt(0) (L-L = 25a) has also been isolated from the reaction of 25a with Pt [P (C₆H₅)₃]₄. Dimanganese decacarbonyl reacts with 25a and 25b to give products of formulae [ (L-L) Mn (CO)₃]₂ and (L-L) Mn₂(CO)₈ respectively. The former is a dimeric complex with one ligand per manganese atom. Bromination of this dimer yields the fac-(L-L)Mn(CO)₃Br isomer. All the ligands mentioned above react with iron carbonyls to give a range of products. The chelate complexes of formulae (L-L)Fe(CO)₃ are isolated when (L-L) = 25a or 25b. A complex of formula (L-L)Fe₂(CO)₆, (L-L = 25a) is also isolated from this reaction. Analogous products have been isolated in previous studies. The ligand 23 reacts with iron pentacarbonyl to give three products of formula (L-L)Fe₂(CO)₈, (L-L)Fe₂(CO)₆ I and (L-L) Fe₂(CO)₆ II. Spectroscopic studies on the latter two complexes show that considerable fragmentation and rearrangement of the ligand has taken place. This has been confirmed in an independent X-ray structural study. The tertiary phosphines 26a and 26b react with iron carbonyls to give the expected complexes of formula LFe(CO)₄. However, variations are seen when the ring size is changed. When L = 26c - 26f in addition to the anticipated LFe(CO)₄ derivatives, compounds of stoichiometry R₂PC-C-CF(CF₂)[sub n]Fe₂(CO)₆ (n = 2,3; R = C₆H₁₁, C₆H₅) are also isolated. Spectroscopic studies indicate the presence of an n³-allyl group which has been confirmed by an independent X-ray structural deter- mination. The fluorinated n³-allyl group is σ bonded to one Fe atom and π-bonded to the other. Coupled products of formulae [Fe(CO)₄R₂PC=C(CF₂)[sub n]₂ (R = C₆H₁₁, n = 3; R = C₆H₅, n = 4) have also been isolated from these reactions. The reactions of n³-allyl complexes, R₂PC-C-CF(CF₂)₂Fe₂(CO)₆ (R = C₆H₅, C₆H₁₁) with triphenyl-phosphine and iodine have been investigated. The complex (C₆H₅)₂PC-C-CF(CF₂)₂Fe₂(CO)₆ has been found to be an effective photochemical catalyst for the isomerization of l-pentene. The photochromism of the ligand, 23 has been investigated by infrared spectroscopy in the solid state.

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2010-03-18

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http://hdl.handle.net/2429/22064

Chemistry

University of British Columbia

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