κ<sup>1</sup>- and κ<sup>2</sup>-Complexes of Fluorenylidene–Allenyl Phosphines and Phosphine Oxides with Palladium Chloride and Iron Carbonyl: Displacement of Trimethylsilyl by Diphenylphosphino via a Stabilized Carbanion
作者:Sandra Milosevic、Emilie V. Banide、Helge Müller-Bunz、Declan G. Gilheany、Michael J. McGlinchey
DOI:10.1021/om200357v
日期:2011.7.25
An attempt to prepare 3,3-(biphenyl-2,2'-diyl)-1-diphenylphosphino-1-(trimethylsilyl)allene, 15, by treatment of 3,3- (bipheny1-2,2'-diyl)-1-lithio-1-(trimethylsilyl)allene with chlorodiphenylphosphine led instead to 3,3-(biphenyl-2,2'-diyl)-1,1-bis(diphenylphosphino)allene, 14. The proposed mechanism invokes attack on the trimethylsilyl group in 15 by liberated chloride to form a stabilized anion that reacts with a second molecule of the chlorophosphine. The diphosphine, 14, reacts with di-iron nonacarbonyl to form monodentate 14-Fe(CO)(4) and the chelate 14-Fe(CO)(3). 9-Ethynyl-9H-fluoren-9-ol and chlorodiphenylphosphine form 3,3-(biphenyl-2,2'-diyl)-1-diphenylphosphinylallene, which is readily deprotonated by triethylamine to generate a stabilized fluorenyl anion, which reacts with a second molecule of the chlorophosphine to furnish 3,3-(biphenyl-2,2'-diyl)-1-diphenylphosphino-1-diphenylphosphinylallene, 26. This bis-phosphine-monoxide (BPMO) reacts with di-iron nonacarbonyl to form initially monodentate P-bonded 26-Fe(CO)(4), which loses a carbonyl, allowing the adjacent allene double bond in 26-Fe(CO)(3) to coordinate to iron and leave the phosphine oxide uncoordinated. In contrast, the BPMO, 26, and (PhCN)(2)PdCl2 yield the phosphine-coordinated, chlorine-bridged dimer 34 and also the chelate 35, in which the palladium is linked to both the diphenylphosphino and diphenylphosphinyl groups via phosphorus and oxygen, respectively. Surprisingly, chlorodiphenylphosphine and 1,4-bis(9-hydroxy-9H-fluorenyl)buta-1,3-diyne, 37, do not yield the expected 3,4-bis(phosphinyl)hexa-1,2,4,5-tetraene, 33, but rather the 1-chloro-2-diphenylphosphinocyclobutene, 38, bearing a spiro-bonded fluorenylidene and a fluorenylidene-allene. All new compounds were characterized by P-31 NMR spectroscopy and X-ray crystallography.