•The formation of perfluoropropenyl transition metal complexes from HFC-1225ye.•The first structurally characterized examples of early TM and bis-substituted perfluoropropenyl organometallic complexes.•An assessment of the electronic steric properties of the perfluoropropenyl ligand based on X-ray diffraction data.The new stable perfluoropropenyl organometallic complexes [(Ph3P)Au(E-CF=CFCF3)], trans-[(Ph3P)2Pt(Z-CF=CFCF3)Cl], trans-[(Ph3P)2Pd(E-CF=CFCF3)Cl], [(COD)Pt(E-CF=CFCF3)2] and [Cp2Ti(E-CF=CFCF3)Cl] have been obtained from the reaction of LiCF=CFCF3–derived from Z-CFH=CFCF3 (HFC-1225ye) – with appropriate transition-metal starting materials. The complexes have been characterized by multinuclear NMR studies (19F,1H, 31P and 13C) and single-crystal structure determinations. Based on the X-ray derived data a comparison is made between σ-bound perfluoropropenyl and perfluorovinyl ligands; whilst they are found to be electronically quite similar on the basis of their trans-influence the perfluoropropenyl group is significantly more sterically-demanding, and it is suggested that this accounts for the predominance of mono-perfluoropropenyl-substituted complexes with enhanced stabilities.Download high-res image (134KB)Download full-size image

•Chiral Au(III) and Au(I) cyclometallated and NHC complexes is reported.•The use of chiral Au complexes in A3-reactions has been studied.•Chiral Au complexes do not effect the stereochemical outcome of A3-reactions.•The intervention of Au nanoparticles in A3-reactions is postulated.A series of cyclometallated and functionalised NHC gold(I) and gold(III) complexes, many of which feature chiral ligands, and their application to A3-coupling reactions is presented. Gold(III) complexes were found to be particularly effective catalysts for the coupling in a range of solvents, however no asymmetric induction was obtained when using chiral gold complexes and the rate of product formation was found to be similar even when using different ligand systems. In-situ NMR analysis of these reactions indicates that decomposition of the catalyst occurs during the course of the reaction while TEM studies revealed the presence of gold nanoparticles in crude reaction mixtures. Taken together these data suggest that the gold nanoparticles, rather than the intact gold complexes, could be the catalytically active species, and if so this may have significant implications for other gold-catalysed systems.Download high-res image (161KB)Download full-size image

Halogen bonding (XB) is a highly-directional class of intermolecular interactions that has been used as a powerful tool to drive the design of crystals in the solid phase. To date, the majority of XB donors have been iodine-containing compounds, with many fewer involving brominated analogues. We report the formation of adducts in the vapour phase from a series of dibromoperfluoroalkyl compounds, BrCF2(CF2)nCF2Br (n = 2, 4, 6), and 1,4-diazabicyclo[2.2.2]octane (DABCO). Single-crystal X-ray diffraction studies of the colourless crystals identified 1,4-diazabicyclo[2.2.2]octane–1,4-dibromoperfluorobutane (1/1), C4Br2F8·C6H12N2, (I), 1,4-diazabicyclo[2.2.2]octane–1,6-dibromoperfluorohexane (1/1), C6Br2F12·C6H12N2, (II), and 1,4-diazabicyclo[2.2.2]octane–1,8-dibromoperfluorooctane (1/1), C8Br2F16·C6H12N2, (III), each of which displays a one-dimensional halogen-bonded network. All three adducts exhibit N…Br distances less than the sum of the van der Waals radii, with butane analogue (I) showing the shortest N…Br halogen-bond distances yet reported between a bromoperfluorocarbon and a nitrogen base [2.809 (3) and 2.818 (3) Å], which are 0.58 and 0.59 Å shorter than the sum of the van der Waals radii.

A series of new perfluoropropenyl-containing phosphines of the type R3−nP(E-CFCFCF3)n (R = Ph, iPr, n = 1, 2; R = tBu, n = 2) have been prepared from the reaction of the hydrofluoroolefin Z-CF3CFCFH (HFO-1225ye) with base and the appropriate chlorophosphine, while reaction with Cl2PCH2CH2PCl2 gave (CF3CFCF)2PCH2CH2P(CFCFCF3)2, the first example of a bidentate perfluoroalkenyl-containing phosphine. An alternative route to these phosphines based on the room- or low-temperature deprotonation of CF3CF2CH2F (HFC-236ea) gives mainly the E-isomer, but also a small amount of the Z-isomer, the ratio of which depends on the reaction temperature. All of the phosphines could be readily oxidised with either H2O2 or urea·H2O2, and the phosphine selenides R3−nP(Se)(E-CFCFCF3)n (R = Ph, n = 1,2; R = iPr, n = 1; R = tBu, n = 2) were also prepared. The steric and electronic properties of these ligands were determined based on their platinum(II), palladium(II) and molybdenum carbonyl complexes. The crystal structures of (CF3CFCF)2PCH2CH2P(CFCFCF3)2, (CF3CFCF)2P(O)CH2CH2P(O)(CFCFCF3)2, iPr2P(Se)(CFCFCF3)2, trans-[PtCl2{Ph(3−n)P(E-CFCFCF3)n}2] (n = 1 or 2), trans-[PdCl2{R2P(E-CFCFCF3)}2] (R = Ph, iPr) and [Mo(CO)4{(CF3CFCF)2PCH2CH2P(CFCFCF3)2}] are reported.

Correction for ‘Perfluoropropenyl-containing phosphines from HFC replacements’ by Alan K. Brisdon et al., Dalton Trans., 2015, DOI: 10.1039/c5dt02043c.

This review describes recent advances in the synthesis, chemistry and applications of phosphine ligands containing one or more perfluoroalkyl, Rf, substituent. The methods reviewed are capable of generating a wide variety of monodentate, bidentate and PCP-pincer ligands containing Rf groups. Based on the chemistry of complexes containing these ligands, and compilations of their spectroscopic data and structural parameters it is shown that fluoroalkyl-containing phosphines have a distinct combination of steric and electronic properties, often quite different to fluoroaryl analogues. The catalytic activities displayed by complexes of these ligands are described.Highlights► Comprehensive survey of monodenate, bidentate and pincer perfluoroalkyl-phosphines. ► A review of recently published methods of synthesizing Rf-containing phosphines. ► Summaries of structures and spectroscopic data available, upto 2011, for fluoroalkyl-phosphines. ► Applications in catalysis.

•We report the reaction of tertiary amines with I(CH2)n(CF2)mCF3 compounds.•When n = 2 elimination occurs to give CH2CH(CF2)mCF3.•When n = 3 quaternisation results to give quaternary ammonium salts.•The completely asymmetric fluoroalkyl-containing quaternary ammonium salt BuMeOctN((CH2)3C8F17)]I is reported.The formation of quaternary ammonium iodides possessing a fluorine-containing chain has been investigated. Reactions of tertiary amines, such as i-PrMe2N and n-BuMe2N with I(CH2)n(CF2)m(CF3), (n = 2, m = 5 and 7) do not cleanly yield the anticipated quaternary ammonium halide salt, instead elimination occurs and [RMe2NH]I (R = i-Pr, n-Bu) and CH2CH(CF2)m(CF3) are formed. This is confirmed by the crystallographic characterisation of [n-BuMe2NH]I which is found to adopt a micellar-type arrangement in the solid state. Increasing the spacer chain-length to n = 3 does result in the desired quaternary ammonium halide salts, [RMe2N(CH2)3(CF2)m(CF3)]I, (m = 3, 7). Quaternisation of MeBuN((CH2)3C8F17) with 1-iodooctane gave the asymmetric quaternary ammonium salt possessing a fluorinated alkyl chain, [n-BuMeOctN((CH2)3C8F17)]I. Unlike in previously studied perprotio systems, low symmetry ammonium systems possessing long fluorinated chains do not result in room temperature ionic liquids.A series of fluoroalkyl-containing quaternary ammonium ionic liquids are reported, including the completely asymmetric salt [BuMeOctN((CH2)3C8F17)]I, prepared by quaternisation of BuMeN(CH2)3C8F17 with octyliodide. Quaternisations involving Rf(CH2)nI n = 3 proceed smoothly, while those of related systems when n = 2 result in elimination, rather than quaternisation, reactions.

A series of new (E)-pentafluoropropenyl complexes of Hg, Ge, Sn, and Pb are reported derived from CFH═CFCF3 ((Z)-HFC-1225ye). Unequivocal assignment of the geometry of the products was achieved via a multinuclear (1H, 13C, 19F, 119Sn, and 199Hg) NMR study. These conclusions are confirmed in the single-crystal X-ray structures of Ph3Ge(CF═CFCF3) and Ph3Sn(CF═CFCF3). In the solid-state structures of both molecules, short contacts are observed between one of the fluorine atoms of the CF3 group and the metal center. The Bu3Sn(CF═CFCF3) compound acts as an effective source of the pentafluoropropenyl group in a series of palladium-catalyzed Stille–Liebeskind reactions to generate new aryl–pentafluoropropenyl systems.

A series of gold(I) phosphine complexes of the type [AuCl{PR2(Rf)}] (R = Et, i-Pr, Cy; Rf = CFCF2; R = Ph, Rf = CFCFH, CClCF2, CCCF3, CF3, i-C3F7, s-C4F9) have been prepared and most have been structurally characterised. All of the complexes are monomeric in the solid state, and a number of secondary interactions are observed – including short intramolecular Au⋯F distances, metal-bound Au–Cl⋯H non-classical hydrogen bonds, fluorous domains and phenyl embraces. Only in the case of [AuCl{PEt2(CFCF2)}] is an aurophilic interaction with an Au⋯Au contact less than the sum of the van der Waals radii observed. Even then, the distance, 3.3458(10) Å, is longer than that previously observed for the related complex with R = Ph; Rf = CFCF2.

The coordination chemistry of the fluorovinyl substituted phosphines PPh2(Z-CFCFH) and PPh2(E-CClCFH) with K2MX4 (M = Pd, Pt; X = Cl, Br, and I) salts has been investigated resulting in the first reported palladium(II) and platinum(II) complexes of phosphines containing partially fluorinated vinyl groups. The complexes have been characterised by a combination of multinuclear [1H, 13C{1H}, 19F, 31P{1H}] NMR spectroscopy, and IR/Raman spectroscopy. The single-crystal X-ray structures of trans-[PdX2{PPh2(CFCFH)}2], X = Cl (1), Br (2), I (3), trans-[PdCl2{PPh2(CClCFH)}2] (4), cis-[PtX2{PPh2(CFCFH)}2], X = Cl (5), Br (6), trans-[PtI2{PPh2(CFCFH)}2] (7), and both cis- and trans-[PtCl2{PPh2(CClCFH)}2] (8), have been determined. Results obtained from spectroscopic and crystallographic data suggest that replacement of a β-fluorine by hydrogen, whilst reducing the steric demand of the ligand, has little effect on the electronic character of the ligand. The presence of a proton in the vinyl group results in short proton–halide secondary interactions in the solid state (d(H⋯X) = 2.72(3) for 1, and 2.92(5) Å for 2) forming an infinite chain ribbon motif.The synthesis of a series of Pd(II) and Pt(II) complexes of partially fluorinated ligands of the type Ph2P(CXCFH) (X = F, Cl) are reported. A comparison of the steric, electronic and solid-state structural mofits of these ligands and complexes with previously reported analogues is made.

The reaction of trimethylsilyl-containing phosphanes with perfluoroiodoalkanes provides a general and convenient route to perfluoroalkyl-containing phosphanes.

The effect on the melting point of the introduction of asymmetry in tetraalkylammonium halide salts has been investigated leading to the synthesis of new, hydrophobic (room temperature) ionic liquids suitable for liquid/liquid electrochemistry; one of these, tri(hexyl)decylammonium tetrakis(pentafluorophenyl)borate, displays the largest electrochemical window observed to date for a biphasic room temperature ionic liquid system.

The reactions of the fluorovinyl-substituted phosphines PPh2(CFCF2) and PPh2(CClCF2), with K2PtX4 (X = Br, I) have been investigated. The resulting complexes have been characterized by a combination of 19F and 31P{1H} NMR, IR and Raman spectroscopy. The reactions of these phosphines with K2PtBr4 yield the monomeric complexes cis-[PtBr2{PPh2(CFCF2)}2] (1) and trans-[PtBr2{PPh2(CClCF2)}2] (2), respectively, whilst the reactions with K2PtI4 yield both the monomeric species trans-[PtI2{PPh2(CXCF2)}2], {X = F (3), Cl (4)}, and the dimeric species [PtI(μ-I){PPh2(CXCF2)}]2, {X = F (5), Cl (6)}. The dimers 5 and 6 represent the first crystallographically characterised platinum(II) iodide-bridged phosphine complexes, and both adopt the symmetric-trans structure.Changing the halogen X in the starting material PPh2(CXCF2) X = F, Cl affords preferentially, on reaction with K2PtBr4, monomeric cis-[PtBr2{PPh2(CFCF2)}2] and trans-[PtBr2{PPh2(CClCF2)}2], respectively. In contrast the reaction with K2PtI4 gives trans-[PtI2{PPh2(CXCF2)}2], and the crystallographically characterized symmetric-trans dimeric species [PtI(μ-I){PPh2(CXCF2)}]2.

The coordination chemistry of the perfluorovinyl phosphines PEt2(CFCF2), PiPr2(CFCF2), PCy2(CFCF2) and PPh(CFCF2)2 to rhodium(I), palladium(II), and platinum(II) centres has been investigated. The electronic properties of the ligands are estimated based on ν(CO) and 1J(Rh–P) values. X-Ray diffraction data for the square-planar Pd(II) and Pt(II) perfluorovinyl-phosphine containing complexes allow estimates of the steric demand for the series of ligands PPh2(CFCF2), PEt2(CFCF2), PiPr2(CFCF2), PCy2(CFCF2) and PPh(CFCF2)2 to be determined. The (CFCF2) fragment is found to be more electron withdrawing than (C6F5) yet sterically less demanding. These ligands therefore provide a range of electron-neutral to phosphite-like electronic properties combined with a range of steric demands. This study also reveals that short intramolecular interactions from the metal centre to the β-fluorine atom cis to phosphorus of the CFCF2groups are observed in all-trans square planar complexes of the ligands. Unusually, the complex [PtCl2{PiPr2(CFCF2)}2] crystallises with both cis- and trans-isomers present in the unit cell. It appears that co-crystallisation of both isomers occurs in order to maximise fluorous regions in the crystal packing, and the extended structure displays short fluorine–fluorine contacts. The generation of mixed geometries seems to be a phenomenon of crystallisation, as solution phase NMR studies reveal the presence of only the trans-isomer.

A series of new perfluoropropenyl-containing phosphines of the type R3−nP(E-CFCFCF3)n (R = Ph, iPr, n = 1, 2; R = tBu, n = 2) have been prepared from the reaction of the hydrofluoroolefin Z-CF3CFCFH (HFO-1225ye) with base and the appropriate chlorophosphine, while reaction with Cl2PCH2CH2PCl2 gave (CF3CFCF)2PCH2CH2P(CFCFCF3)2, the first example of a bidentate perfluoroalkenyl-containing phosphine. An alternative route to these phosphines based on the room- or low-temperature deprotonation of CF3CF2CH2F (HFC-236ea) gives mainly the E-isomer, but also a small amount of the Z-isomer, the ratio of which depends on the reaction temperature. All of the phosphines could be readily oxidised with either H2O2 or urea·H2O2, and the phosphine selenides R3−nP(Se)(E-CFCFCF3)n (R = Ph, n = 1,2; R = iPr, n = 1; R = tBu, n = 2) were also prepared. The steric and electronic properties of these ligands were determined based on their platinum(II), palladium(II) and molybdenum carbonyl complexes. The crystal structures of (CF3CFCF)2PCH2CH2P(CFCFCF3)2, (CF3CFCF)2P(O)CH2CH2P(O)(CFCFCF3)2, iPr2P(Se)(CFCFCF3)2, trans-[PtCl2{Ph(3−n)P(E-CFCFCF3)n}2] (n = 1 or 2), trans-[PdCl2{R2P(E-CFCFCF3)}2] (R = Ph, iPr) and [Mo(CO)4{(CF3CFCF)2PCH2CH2P(CFCFCF3)2}] are reported.

A series of gold(I) phosphine complexes of the type [AuCl{PR2(Rf)}] (R = Et, i-Pr, Cy; Rf = CFCF2; R = Ph, Rf = CFCFH, CClCF2, CCCF3, CF3, i-C3F7, s-C4F9) have been prepared and most have been structurally characterised. All of the complexes are monomeric in the solid state, and a number of secondary interactions are observed – including short intramolecular Au⋯F distances, metal-bound Au–Cl⋯H non-classical hydrogen bonds, fluorous domains and phenyl embraces. Only in the case of [AuCl{PEt2(CFCF2)}] is an aurophilic interaction with an Au⋯Au contact less than the sum of the van der Waals radii observed. Even then, the distance, 3.3458(10) Å, is longer than that previously observed for the related complex with R = Ph; Rf = CFCF2.

The effect on the melting point of the introduction of asymmetry in tetraalkylammonium halide salts has been investigated leading to the synthesis of new, hydrophobic (room temperature) ionic liquids suitable for liquid/liquid electrochemistry; one of these, tri(hexyl)decylammonium tetrakis(pentafluorophenyl)borate, displays the largest electrochemical window observed to date for a biphasic room temperature ionic liquid system.

Correction for ‘Perfluoropropenyl-containing phosphines from HFC replacements’ by Alan K. Brisdon et al., Dalton Trans., 2015, DOI: 10.1039/c5dt02043c.

The reaction of trimethylsilyl-containing phosphanes with perfluoroiodoalkanes provides a general and convenient route to perfluoroalkyl-containing phosphanes.