819082-43-4Relevant academic research and scientific papers
Acetylacetonato, pentachlorophenolato and carboxylato rhodium(I) complexes and their reactivity in the C-C coupling reaction of olefins and diazoalkanes
Werner, Helmut,Mahr, Norbert,Schneider, Michael E.,Bosch, Marco,Wolf, Justin
, p. 2645 - 2657 (2004)
This work extends the series of chelate rhodium(I) complexes with Rh(PiPr3)2 as the core unit.The complexes not only react with ethene but also with diazoalkanes. The acetylacetonato complexes [Rh(κ2-O-O)(C2H4)(PiPr3)] (O-O = acac 5, acac-f3 6, acac-f6 7) and [Rh(κ 2-O-O)(PiPr3)2] (O-O = acac 10, acac-f 6 11) were prepared from either [Rh(κ2-O-O)(C 2H4)2] (2-4), [Rh(η3-C 3H5)(PiPr3)2] (8) or [RhCl(PiPr 3)2]2 (9) as the starting materials.While attempts to obtain the diazoalkane derivatives [Rh(κ2-O-O) (N2CR2)(PiPr3)] (R Ph, p-Tol) failed, treatment of 5-7 with N2CC4Cl4 gave the corresponding substitution products [Rh(κ2-O-O)(N2CC 4Cl4)(PiPr3)] (12-14) in good yields.The reaction of 8 with C6Cl5OH afforded the square-planar complex [Rh(κ2-OC6Cl5)(PiPr 3)2] (15), in which the pentachlorophenolato ligand is coordinated in a chelating fashion.From 15 and C2H4, O2 and N2CPh2 the 1:1 adducts trans-[Rh(κ1-OC6Cl5)(L)(PiPr 3)2] (16-18) were prepared.Compound 15 catalyzes the reaction of ethene with diaryldiazomethanes to give, instead of 1,1-diarylcyclopropanes, the isomeric olefins R2CCHCH3 (R = C6H5 1b, p-C6H4Me 19, p-C 6H4Cl 20) as the main products.The carboxylato complexes [Rh(κ2-O2CMe)(PiPr3)2] (21) and [Rh(κ2-O2CCF3)(PiPr3) 2] (25) react with N2CRR′ (R = R′ = C 4Cl4; R = R′ = Ph; R = H, Ph, R′ = C(O)Ph) by opening the chelate bond to give the four-coordinate 1:1 adductstrans- [Rh(κ1-O2CMe)(N2CRR′)(PiPr 3)2] (22-24) and trans-[Rh(κ1-O 2CCF3)(N2CRR′)(PiPr3) 2] (26-28), respectively. Treatment of 25 with PhCHN2 produced the dinitrogen complex trans-[Rh(κ1-O 2CCF3)(N2)(PiPr3)2] (29). In contrast to the trifluoracetato compound 25, which catalyzes the reaction of ethene and diaryldiazomethanes N2CRR′ to give mainly the trisubstituted olefins R′RCCHCH3, the corresponding reaction of C2H4 and N2CRR′ with acetato complex 21 as the catalyst affords the isomeric ethene derivatives CH 2CHCHRR′ as the major products. A mechanism for this unexpected C-C coupling reaction is discussed.
