73440-23-0Relevant academic research and scientific papers
Complexes of Rhodium and Iridium with the β-Ketophosphines PBut2(CH2COR) (R=Ph or But)
Empsall, H. David,Johnson, Stephen,Shaw, Bernard L.
, p. 302 - 307 (2007/10/02)
The bulky β-ketophosphines PBut2(CH2COPh) (Q) and PBut2(CH2COBut) (Q') are shown to behave towards rhodium or iridium either as unidentate ligands (through phosphorus), as bidentate ligands through phosphorus and the keto-group, or as bidentate enolate ions.Treatment of with Q or Q' gives trans- or trans-.These react with sodium methoxide to give complexes of type which with hydrogen chloride give back trans-t2(CH2COR)>2>.The salt RhCl3*3H2O with PBut2(CH2COPh) gives (4a) in which both phosphines are bidentate and which the keto-group is strongly co-ordinated, not being displaced by vigorous treatment with carbon monoxide.This six-co-ordinate rhodium(III) complex with sodium methoxide rapidly gives what appears to be an intensely blue rhodium(II) complex .Iridium trichloride with PBut2(CH2COR) similarly gives the six-co-ordinate t (4c)>.These with sodium ethoxide give purple five-co-ordinate square-pyramidal hydrides (7a) and (7b) which are quite stable to prolonged exposure to air and show 1H(hydride) shifts to exceptionally high field.They both take up carbon monoxide to give colourless hydridocarbonyls (9a) and (9b) which lose carbon monoxide on heating to give back the five-co-ordinate hydrides.Carbonylation of Na2 followed by addition of PBut2(CH2COPh) gives (11a) with an unco-ordinated keto-group.With base (NaOEt) this gives a mixture of (9a) and trans-t2(CH2COPh)>2> (unidentate phosphines).Similar addition of PBut2(CH2COBut) to a carbonylated solution of Na2 gives a t2CH2COBut>2> (10a) contaminated with about 10percent of (11b).When this mixture is heated in chloroform it gives almost pure (11b) contaminated by ca. 2-3percent of (10a).Proton and 31P n.m.r. and i.r. data are given and discussed.
