Halogen bonding is an intermolecular interaction capable of being used to direct extended structu... more Halogen bonding is an intermolecular interaction capable of being used to direct extended structures. Typical halogen-bonding systems involve a noncovalent interaction between a Lewis base, such as an amine, as an acceptor and a halogen atom of a halofluorocarbon as a donor. Vapour-phase diffusion of 1,4-diazabicyclo[2.2.2]octane (DABCO) with 1,2-dibromotetrafluoroethane results in crystals of the 1:1 adduct, C2Br2F4·C6H12N2, which crystallizes as an infinite one-dimensional polymeric structure linked by intermolecular N...Br halogen bonds [2.829 (3) Å], which are 0.57 Å shorter than the sum of the van der Waals radii.
Correction for 'Perfluoropropenyl-containing phosphines from HFC replacements' by... more Correction for 'Perfluoropropenyl-containing phosphines from HFC replacements' by Alan K. Brisdon et al., Dalton Trans., 2015, DOI: 10.1039/c5dt02043c.
Journal of Fluorine Chemistry 2013 156 152 157, 2013
ABSTRACT The formation of quaternary ammonium iodides possessing a fluorine-containing chain has ... more ABSTRACT 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.
ABSTRACT A new route to perfluorovinyl compounds, recently reported by us, has been used to prepa... more ABSTRACT 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(CFCF2)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) Å in Cp2Ti(CFCF2)2 and Cp2Ti(CFCF2)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.
ABSTRACT A dimethylbenzylamine gold complex is found to be an effective catalyst for the three-co... more ABSTRACT A dimethylbenzylamine gold complex is found to be an effective catalyst for the three-component coupling reactions of aldehydes, terminal alkynes, and amines.
ABSTRACT A new route to perfluorovinyl compounds, recently reported by us, has been used to prepa... more ABSTRACT 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(CFCF2)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) Å in Cp2Ti(CFCF2)2 and Cp2Ti(CFCF2)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.
ABSTRACT The formation of quaternary ammonium iodides possessing a fluorine-containing chain has ... more ABSTRACT 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.
Raman data suggest that a crystallographically determined Cl3CD...F2BF2- interaction in the solid... more Raman data suggest that a crystallographically determined Cl3CD...F2BF2- interaction in the solid-state structure of [Ru(CNBut)(CO)(eta2-C6H4-2-CHO)(PPh3)2][BF4].2CDCl3 is an example of a blue-shifting bifurcated hydrogen bond. The nu(C-D) band blue-shifts 5 cm-1 to 2269 cm-1 compared to 2264 cm-1 for CDCl3 in the gas phase and 20 cm-1 from frozen CDCl3 at 2249 cm-1. A conventional interpretation of these band shifts would suggest that the CCl2 fragment of DCCl3 is a stronger hydrogen-bond acceptor than the BF2 fragment of a BF4- group.
The reactions of the group 15 trihalides, MX(3) (M = As, Sb, Bi; X = Cl, Br), with the phosphine ... more The reactions of the group 15 trihalides, MX(3) (M = As, Sb, Bi; X = Cl, Br), with the phosphine selenide SeP(p-FC(6)H(4))(3) result in the formation of co-crystals of formula MX(3)·SeP(p-FC(6)H(4))(3). No reaction was observed with MI(3) (M = As, Sb, Bi). The structures of MX(3)·SeP(p-FC(6)H(4))(3) (M = As, X = Br 2; M = Sb, X = Cl 3; M = Bi, X = Cl 5; M = Bi, X = Br 6) have been established, and are isomorphous, crystallising in the cubic I23 space group. All the structures feature a primary MX(3) unit, which has three weak secondary MSe interactions to SeP(p-FC(6)H(4))(3) molecules. However, each of these SeP(p-FC(6)H(4))(3) molecules bridges three MX(3) molecules, resulting in the generation of an M(4)Se(4) (M = As, Sb, Bi) distorted cuboid linked by the pnictogen-chalcogen interactions. Four opposing corners of the cuboid are occupied by the M atom (M = As, Sb, Bi) of an MX(3) pyramid, and the other four by the selenium atom of the phosphine selenide.
Acta Crystallographica Section C Crystal Structure Communications, 2001
The title compound, N,N'-difluoro-N,N'-ethylenedi-p-toluenesulfonamide, C(16)H(18... more The title compound, N,N'-difluoro-N,N'-ethylenedi-p-toluenesulfonamide, C(16)H(18)F(2)N(2)O(4)S(2).CHCl(3), is a novel stable compound of the N-F class of reagents containing two R(2)N-F functionalities. The compound, as the chloroform solvate, is the first such bis(N-F) compound to be structurally characterized. It adopts a solid-state structure in which the two aromatic rings are antiperiplanar and a combination of weak C-H...F and C-H...O hydrogen bonds [distances and angles range from 3.265 (4) to 3.439 (4) A and 150 to 170 degrees, respectively] and pi-stacking between the rings of different molecules (separations of 3.717 and 3.926 A) results in a solid-state structure containing well defined channels in which CHCl(3) solvent molecules are located. The N-F distances are 1.428 (3) and 1.433 (3) A.
The effect on the melting point of the introduction of asymmetry in tetraalkylammonium halide sal... more 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 coordination chemistry of the perfluorovinyl phosphines PEt2(CF=CF2), P(i)Pr2(CF=CF2), PCy,(C... more 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.
Halogen bonding is an intermolecular interaction capable of being used to direct extended structu... more Halogen bonding is an intermolecular interaction capable of being used to direct extended structures. Typical halogen-bonding systems involve a noncovalent interaction between a Lewis base, such as an amine, as an acceptor and a halogen atom of a halofluorocarbon as a donor. Vapour-phase diffusion of 1,4-diazabicyclo[2.2.2]octane (DABCO) with 1,2-dibromotetrafluoroethane results in crystals of the 1:1 adduct, C2Br2F4·C6H12N2, which crystallizes as an infinite one-dimensional polymeric structure linked by intermolecular N...Br halogen bonds [2.829 (3) Å], which are 0.57 Å shorter than the sum of the van der Waals radii.
Correction for 'Perfluoropropenyl-containing phosphines from HFC replacements' by... more Correction for 'Perfluoropropenyl-containing phosphines from HFC replacements' by Alan K. Brisdon et al., Dalton Trans., 2015, DOI: 10.1039/c5dt02043c.
Journal of Fluorine Chemistry 2013 156 152 157, 2013
ABSTRACT The formation of quaternary ammonium iodides possessing a fluorine-containing chain has ... more ABSTRACT 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.
ABSTRACT A new route to perfluorovinyl compounds, recently reported by us, has been used to prepa... more ABSTRACT 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(CFCF2)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) Å in Cp2Ti(CFCF2)2 and Cp2Ti(CFCF2)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.
ABSTRACT A dimethylbenzylamine gold complex is found to be an effective catalyst for the three-co... more ABSTRACT A dimethylbenzylamine gold complex is found to be an effective catalyst for the three-component coupling reactions of aldehydes, terminal alkynes, and amines.
ABSTRACT A new route to perfluorovinyl compounds, recently reported by us, has been used to prepa... more ABSTRACT 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(CFCF2)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) Å in Cp2Ti(CFCF2)2 and Cp2Ti(CFCF2)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.
ABSTRACT The formation of quaternary ammonium iodides possessing a fluorine-containing chain has ... more ABSTRACT 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.
Raman data suggest that a crystallographically determined Cl3CD...F2BF2- interaction in the solid... more Raman data suggest that a crystallographically determined Cl3CD...F2BF2- interaction in the solid-state structure of [Ru(CNBut)(CO)(eta2-C6H4-2-CHO)(PPh3)2][BF4].2CDCl3 is an example of a blue-shifting bifurcated hydrogen bond. The nu(C-D) band blue-shifts 5 cm-1 to 2269 cm-1 compared to 2264 cm-1 for CDCl3 in the gas phase and 20 cm-1 from frozen CDCl3 at 2249 cm-1. A conventional interpretation of these band shifts would suggest that the CCl2 fragment of DCCl3 is a stronger hydrogen-bond acceptor than the BF2 fragment of a BF4- group.
The reactions of the group 15 trihalides, MX(3) (M = As, Sb, Bi; X = Cl, Br), with the phosphine ... more The reactions of the group 15 trihalides, MX(3) (M = As, Sb, Bi; X = Cl, Br), with the phosphine selenide SeP(p-FC(6)H(4))(3) result in the formation of co-crystals of formula MX(3)·SeP(p-FC(6)H(4))(3). No reaction was observed with MI(3) (M = As, Sb, Bi). The structures of MX(3)·SeP(p-FC(6)H(4))(3) (M = As, X = Br 2; M = Sb, X = Cl 3; M = Bi, X = Cl 5; M = Bi, X = Br 6) have been established, and are isomorphous, crystallising in the cubic I23 space group. All the structures feature a primary MX(3) unit, which has three weak secondary MSe interactions to SeP(p-FC(6)H(4))(3) molecules. However, each of these SeP(p-FC(6)H(4))(3) molecules bridges three MX(3) molecules, resulting in the generation of an M(4)Se(4) (M = As, Sb, Bi) distorted cuboid linked by the pnictogen-chalcogen interactions. Four opposing corners of the cuboid are occupied by the M atom (M = As, Sb, Bi) of an MX(3) pyramid, and the other four by the selenium atom of the phosphine selenide.
Acta Crystallographica Section C Crystal Structure Communications, 2001
The title compound, N,N'-difluoro-N,N'-ethylenedi-p-toluenesulfonamide, C(16)H(18... more The title compound, N,N'-difluoro-N,N'-ethylenedi-p-toluenesulfonamide, C(16)H(18)F(2)N(2)O(4)S(2).CHCl(3), is a novel stable compound of the N-F class of reagents containing two R(2)N-F functionalities. The compound, as the chloroform solvate, is the first such bis(N-F) compound to be structurally characterized. It adopts a solid-state structure in which the two aromatic rings are antiperiplanar and a combination of weak C-H...F and C-H...O hydrogen bonds [distances and angles range from 3.265 (4) to 3.439 (4) A and 150 to 170 degrees, respectively] and pi-stacking between the rings of different molecules (separations of 3.717 and 3.926 A) results in a solid-state structure containing well defined channels in which CHCl(3) solvent molecules are located. The N-F distances are 1.428 (3) and 1.433 (3) A.
The effect on the melting point of the introduction of asymmetry in tetraalkylammonium halide sal... more 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 coordination chemistry of the perfluorovinyl phosphines PEt2(CF=CF2), P(i)Pr2(CF=CF2), PCy,(C... more 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.
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