Brad Berven

Highly Fluorous Bidentate Phosphines

Brad M. Berven et al. — Mon, 18 Apr 2011 15:41:25 PDT

The reaction of tetrachlorodiphosphines [Cl2P(CH2)nPCl2; n = 2-4] with fluorous aromatic precursors 4-bromo(perfluorohexyl)benzene and 4-(perfluorohexyl)phenol gave a series of fluorous-tagged diphosphines [(p-C6F13C6H4)2P(CH2)nP(C6H4C6F13-p)2; n = 2-4] and a new diphosphonite [(p-C6F13C6H4O)2P(CH2)3P(OC6H4C6F13-p)2]. The improved synthesis of 1,3-bis(dichlorophosphino)propane (dcpp), involved the facile chlorination of the corresponding primary phosphine with triphosgene. Fluorinated diimines RN=C(CH3)C(CH3)=NR, where R = p-C6H4C6F13 or p-C6H4C8F17 have also been prepared, and were found to be air-stable alternatives to the highly air-sensitive phosphorus-containing ligands. All compounds were characterised by a variety of techniques including NMR, IR, MS and microanalysis. The successful reduction of the phosphine-oxides [(p-C6F13C6H4)2P(O)(CH2)nP(O)(C6H4C6F13-p)2; n = 2,3] with phenylsilane is also presented.

Highly Fluorous Complexes of Ruthenium and Osmium and Their Solubility in Supercritical Carbon Dioxide

Brad M. Berven et al. — Mon, 18 Apr 2011 15:32:43 PDT

A series of ruthenium and osmium complexes containing highly fluorous diphosphine ligands FPPF = (F13C6C6H4-p)2P(CH2)2P(p-C6H4C6F13)2 (dfppe) and (F13C6C6H4-p)2P(CH2)3P(p-C6H4C6F13)2 (dfppp) has been prepared. The fluorous diphosphine ligands incorporate four C6F13 “fluoro-ponytails”, and these have been effective in solubilizing the complexes in supercritical carbon dioxide (scCO2). Precise solubility measurements in scCO2 were performed for some of the complexes. The new complexes [MX2(FPPF)2] and [MX(FPPF)(η-C5H5)], M = Ru, Os, X = Cl, Br, have been characterized by a number of spectroscopic techniques and their electrochemical properties measured, three of the ruthenium complexes also being characterized by single-crystal X-ray studies. The noncovalent interactions observed in the X-ray structures have been analyzed by the Hirshfeld surface approach, putting them on a more solid footing. The fluorinated complexes show significantly different solvation properties from those of the analogous unfluorinated compounds, particularly with respect to their behavior in common organic solvents and their good scCO2 solubility.

Highly Fluorous Complexes of Nickel, Palladium and Platinum: Solubility and Catalysis in High Pressure CO2

Brad M. Berven et al. — Mon, 18 Apr 2011 15:26:25 PDT

A variety of Group 10 metal complexes [MXY(dfppp)], M = Ni, X, Y = Cl, Br, M = Pd, Pt, X, Y = Cl or CH3, containing the recently reported highly fluorous diphosphine ligand, dfppp, 1,3-bis[di(fluoroponytail)phosphino]propane, {(p-F13C6C6H4)2P}2(CH2)3 have been synthesised. They have been characterised by NMR, mass spectrometry and microanalysis, with two platinum complexes, [PtCl2(dfppp)] and [PtClMe(dfppp)], structurally characterised by single crystal X-ray diffraction studies. The highly fluorous nature of the ligands affords the complexes good supercritical CO2 solubility as measured by supercritical fluid extraction (SFE), and has allowed for the copolymerisation of CO and ethylene using [PdClMe(dfppp)] as the catalyst precursor and CO2 as the solvent. Additionally, PtCl2 complexes of the new ligands dfppb, {(p-F13C6C6H4)2P}2(CH2)4, and dfpop, {(p-F13C6C6H4O)2P}2(CH2)3, have also been prepared and characterised.