Alan K. Brisdon

Recent advances in fluorovinyl-containing compounds

Abstract The reaction of the HFC-replacements CF3CH2F (HFC-134a) and CF3CH2Cl (HCFC-133a) with two equivalents of butyllithium generates, in high yield, the fluorovinyllithium reagents CF2CFLi and CF2CClLi, respectively. These lithium reagents have been used to synthesise fluorovinyl-containing transition metal and main-group compounds in good yields. The resulting compounds may themselves then be used as stable transfer reagents. Here we report the synthesis of new fluorovinyl-containing organometallic complexes, fluorovinyl-containing phosphine ligands of the type RnP(CXCF2)3−n (n=1, 2; X=Cl, F) and their complexes. The single crystal X-ray structures of [Fe(η5-C5H5)(CO)2(CClCF2)], cis-[PtBr2{PEt2(CFCF2)}2] and trans-[PtCl2{PPh2(CClCF2)}2] are reported.

CFC replacement HCFC-133a (CF3CH2Cl) as a convenient precursor for the synthesis of chlorodifluorovinyl-metal derivatives of main group and transition metal elements: the first X-ray structural characterisation of chlorodifluorovinyl-containing organometallic complexes

Abstract The one-pot reaction of the CFC replacement 1-chloro-2,2,2-trifluoroethane (CF3CH2Cl, HCFC-133a) with two equivalents of butyllithium in diethylether at −78°C followed by the addition of main group or transition metal halides results in good yields of the metal-chlorodifluorovinyl-containing compounds R3Sn(CClCF2) {R=Me, Et, Bu}, Sn(CClCF2)4, Sb(CClCF2)3, Hg(CClCF2)nCl(2−n) (n=1,2), trans-[Ni(CClCF2)2(PBu3)2], trans-[Pd(CClCF2)2(PBu3)2] and [Au(CClCF2)(PPh3)]. The molecular structures of Hg(CClCF2)Cl, trans-[Pd(CClCF2)2(Bu3P)2] and [Au(CClCF2)(PPh3)] have been obtained from single crystal data; these are the first such structural data to be reported for any chlorodifluorovinyl-containing organometallic complexes. The molecular structure of [Au(CFCF2)(PPh3)], which was prepared using a similar method based on CF3CH2F (HFC-134a), is also reported and compared with that of the chlorodifluorovinyl analogue.

The first early transition metal perfluorovinyl complexes: the synthesis of Cp2M(CFCF2)nX2−n (Cp: η5-C5H5−; M=Ti, Zr; X=Cl or F) and structures of Cp2Ti(CFCF2)nX2−n (X=Cl, F) via Ti K-edge EXAFS studies

A new route to perfluorovinyl compounds, recently reported by us, has been used to prepare the first examples of early transition metal complexes of the type Cp2M(CFCF2)nXn−2 (Cp: η5-C5H5−; M=Ti, Zr; X=Cl or F). These compounds are obtained in high yield from the two-stage, one-pot, reaction of HFC-134a (CF3CH2F) with two equivalents of BuLi, followed by addition of Cp2MX2 (M=Ti, Zr, X=F, Cl). For two of the titanium-containing compounds Ti K-edge EXAFS data have been recorded from which distances for the titanium–carbon bond of the perfluorovinyl group of 2.033(12) and 2.050(18) A in Cp2Ti(CFCF2)2 and Cp2Ti(CFCF2)F are obtained. This is the first report of structural data for any perfluorovinyl organometallic compound, and the distances obtained are consistent with the perfluorovinyl group binding in a simple sigma fashion.

A generic route to fluoroalkyl-containing phosphanes

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

First structurally confirmed example of the formation of a gold(III) carbon bond via transmetallation with a boroxine

Cyclometallated gold(III) complexes containing functionalised (2-dimethylaminomethyl)phenyl ligands have been prepared by transmetallation from boroxines to sodium tetrachloroaurate.

The coordination chemistry of perfluorovinyl substituted phosphine ligands, a crystallographic and spectroscopic study. Co-crystallisation of both cis- and trans-isomers of [PtCl2{PiPr2(CFCF2)}2] within the same unit cell

The coordination chemistry of the perfluorovinyl phosphines PEt2(CF=CF2), P(i)Pr2(CF=CF2), PCy,(CF=CF2) and PPh(CF=CF2)2 to rhodium(I), palladium(II), and platinum(II) centres has been investigated. The electronic properties of the ligands are estimated based on v(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(CF=CF2), PEt2(CF=CF2), P(i)Pr2(CF=CF2), PCy2(CF=CF2) and PPh(CF=CF2)2 to be determined. The (CF=CF2) 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 beta-fluorine atom cis to phosphorus of the CF=CF2 groups are observed in all-trans square planar complexes of the ligands. Unusually, the complex [PtCl2{P(i)Pr2(CF=CF2)}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.

FLUOROVINYL ORGANOMETALLIC COMPOUNDS : AN HISTORICAL REVIEW AND SOME RECENT ADVANCES

Abstract This review describes the historically important routes to fluorovinyl organometallic species of the type M-(CXCX 2 ), where M is a main-group or transition-metal element and one, or more, of the substituent atoms, X, is fluorine, the others being either other halogens, or hydrogen. A number of newer synthetic methods are described which have resulted in the preparation of a wider range of examples of such compounds. The structure, spectrocopy, properties, reactivity and future prospects for this class of compounds are described.

Hydrofluorocarbon 245fa: a versatile new synthon in alkyne chemistry.

The CFC replacement 1,1,1,3,3-pentafluoropropane (HFC 245 fa) has been established as a convenient source of trifluoropropynyllithium under mild conditions; a range of novel and known trifluoropropynyl-containing systems has been prepared in a one-pot procedure.

Osmium LIII edge extended X-ray absorption fine-structure studies on the osmium(VIII) oxide-fluorides, OsO3F2, K[OsO3F3] and Cs2[OsO4F2]

Abstract Osmium LIII edge extended X-ray absorption fine-structure data have been obtained for the title compounds and refined to give, for OsO3F2, d(OsO)1.70 A and d(OsF)  1.89 and 2.09 A, for K[OsO3F3], d(OsO)1.70 A and d(OsF)1.92 A and, for Cs2[OsO4F2], d(OsO)  1.70 A and d(OsF)  2.05 A (bond lengths accurate to ±0.02 A).

Immiscible electrolyte systems based on asymmetric hydrophobic room temperature ionic liquids

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.