186466-39-7Relevant academic research and scientific papers
Comparison of the reactions of some bisphosphines with two related dinuclear rhodium complexes
County, Geoffrey R.,Dickson, Ron S.,Fallon, Gary D.,Jenkins, Susan M.,Johnson, Julian
, p. 279 - 293 (1996)
The reactions of some phosphines and bisphosphines with the dirhodium complexes (η5-C5H5)2Rh2(μ-CO)(μ2-n2-CF3C2CF3) (I) and (η5:η5-C5H4CH2C5H4)Rh2(CO)5(μ2-η1:η1-CF3C2CF3) (II) have been compared. The complexes (n5-C5H5)2Rh2(CO){η1-Ph2P(CH2)nPPh2}(μ2-η1:η1-CF3C2CF3) (III, n = 1-4), which are formed from (I) and the appropriate bisphosphine, all have a trans arrangement of the carbonyl and bisphosphine ligands. When left in solution, the complex (III, n = 1) loses CO to form (η5-C5H5)2Rh2(μ2-η1:η1-dppm)(μ2η1:η1-CF3C2CF3) (IV), but the other complexes are stable. The complex (II) was prepared to force a change of stereochemistry on the products of the addition reactions. Treatment of (II) with the phosphines P(p-MeC6H4)3 and PPh2H, and the bisphosphines Ph2P(CH2)nPPh2 (n = 1-4) gave (η5:η5-C5H4CH2C5H4)2Rh2(CO)(L)(μ2-η1:η1-CF3C2CF3) in which CO and L adopt a cis configuration on the Rh-Rh bond. UV irradiation of (η5:η5-C5H4CH2C5H4)Rh2(CO)(PPh2H)(μ2-η1:η1-CF3C2CF3) (VII) results in formal insertion of the alkyne into the P-H bond to give (η5:η5-C5H4CH2C5H4)Rh2(CO){μ2-PPh2C(CF3)C(CF3)H} (VIII). Unlike (III, n= 1), (η5:η5-C5H4CH2C5H4)Rh2(CO)(η1-dppm)(μ2-η1:η1CF3C2CF3) (IX n = 1) shows no tendency to lose CO in solution. Some bis(dinuclear) complexes [(η5-C5H5)2Rh2(CO)(μ2η1:η1-CF3C2CF3)]2(μ2-η1:η1-Ph2P(CH2)nPPh2}) (V, n = 2-4) and [(η5:η5-C5H4CH2C5H4)Rh2(CO)(μ2-η1:η1-CF3C2CF3)]2(μ-η1:η1-dppb) (X) were formed when two equivalents of (I) or (II) were treated with the bisphosphine. The crystal and molecular structures of (III, n = 2), (IV) and (IX, n = 1) were determined by X-ray crystallography.
