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The molecule (η5-pentamethylcyclopentadienyl)(methyldiphenylphosphinite-P)dichlororhodium(III), [(η5-C5Me5)RhCl2(PPh2OMe)], crystallizes in the monoclinic crystal system in space group P21/c with unit cell parameters a = 16.056(3) A, b = 9.4331(18) A, c = 15.745(3) A, β = 108.330(4)°, V = 2263.8(7) A3 and Z = 4. There is three-legged piano stool geometry about Rh. The Rh-P distance of 2.278(2) A is shorter than those of [(η5-C5Me5)RhCl2(PPh2OR)] where R is an aryl group, and longer than those found in [(η5-C5Me5)RhCl2{PPh(OR)2}]. The structure reveals significant distortion of the pentamethylcyclopentadienyl towards ′η3,η2-enyl-ene′ coordination.

A series of mercury(II) ionic liquids, [C(n)mim][HgX(3)], where [C(n)mim] = n-alkyl-3-methylimidazolium with n = 3, 4 and X = Cl, Br, have been synthesized following two different synthetic approaches, and structurally characterized by means of single-crystal X-ray structure analysis ([C(3)mim][HgCl(3)] (1), Cc (No. 9), Z = 4, a = 16.831(4) Å, b = 10.7496(15) Å, c = 7.4661(14) Å, β = 105.97(2)°, V = 1298.7(4) Å(3) at 298 K; [C(4)mim][HgCl(3)] (2), Cc (No. 9), Z = 4, a = 17.3178(28) Å, b = 10.7410(15) Å, c = 7.4706(14) Å, β = 105.590(13)°, V = 1338.5(4) Å(3) at 170 K; [C(3)mim][HgBr(3)] (3), P2(1)/c (No. 14), Z = 4, a = 10.2041(10) Å, b = 10.7332(13) Å, c = 14.5796(16) Å, β = 122.47(2)°, V = 1347.2(3) Å(3) at 170 K; [C(4)mim][HgBr(3)] (4), Cc (No. 9), Z = 4, a = 17.093(3) Å, b = 11.0498(14) Å, c = 7.8656(12) Å, β = 106.953(13)°, V = 1421.1(4) Å(3) at 170 K). Compounds 1, 2, and 4 are isostructural and are characterized by strongly elongated trigonal [HgX(5)] bipyramids, which are connected via common edges in chains. In contrast, 3 contains [Hg(2)Br(6)] units formed by two edge-sharing tetrahedra. With melting points of 69.3 °C (1), 93.9 °C (2), 39.5 °C (3), and 58.3 °C (4), all compounds qualify as ionic liquids. 1, 2, and 4 solidify upon fast cooling as glasses, whereas 3 crystallizes. Cyclic voltammetry shows two separate, quasi-reversible redox processes, which can be associated with the 2Hg(2+)/Hg(2)(2+) and Hg(2)(2+)/2Hg redox couples.

New ionic liquids based on azepanium and 3-methylpiperidinium cations have been synthesised; they exhibit moderate viscosities and remarkably wide electrochemical windows, thereby showing promise, inter alia, as electrolytes and battery materials, and as synthetic media.

The combination of different boron cluster anions and some of the cations typically found in the composition of ionic liquids has been possible by straightforward metathetic reactions, producing new low melting point salts; the imidazolium cations have been systematically studied, [C(n)mim]+ (when [C(n)mim]+ = 1-alkyl-3-methylimidazolium; n = 2, 4, 6, 8, 10, 12, 14, 16, or 18). Melting points increase in the anionic order [Co(C2B9H11)2]-[C2B9H12]-[B10Cl10]2-[B12Cl12]2-. Nevertheless, alkyl chain length dramatically influences the thermal behavior, suggesting that packing inefficiency is the main cause of the existence of room temperature ionic liquids. The salts [C(n)mim][Co(C2B9H11)2] (n = 4, 6, 8, 10, 12 or 14) are liquids at room temperature, presenting strikingly low glass transition temperatures (or = -34 degrees C). The salts [C(n)mim]2[X] ([X]2- = [B10Cl10]2- or [B12Cl12]2-, n = 16 or 18) show liquid crystal phases between the solid and liquid states. Tetraalkylphosphonium salts of [B10Cl10]2- have also been prepared. Physical properties, such as thermal stability, density, or viscosity, have been measured for some selected samples. The presence of the perhalogenated dianion [B12Cl12]2- in the composition of the imidazolium salts renders highly thermally stable compounds. For example, [C2mim]2[B12Cl12] starts to decompose above 480 degrees C in a dynamic TGA analysis under a dinitrogen atmosphere. Crystal structures of [C2mim][Co(C2B9H11)2] and [C2mim]2[B12Cl12] have been determined. 1H NMR spectra of selected imidazolium-boron cluster anion salts have been recorded from solutions as a function of the concentration, showing trends related to the cation-anion interactions.

The coordination of olefins to square-planar Pd(II) and Pt(II) complexes containing 2,9-dimethylphenanthroline ( L1) often involves a change of color associated with a change of geometry at the metal center. In order to obtain suitable colorimetric detectors for ethylene gas, a series of new Pd(II) and Pt(II) compounds with a range of 2,9-disubstituted phenanthroline ligands [2,9-di- n-butyl-1,10-phenanthroline ( L2), 2,9-di- s-butyl-1,10-phenanthroline ( L3), 2,9-diphenyl-1,10-phenanthroline ( L4), and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine, L5)] have been prepared and their reactivity toward ethylene investigated both in solution and after depositing the detector compounds on a variety of solid supports. The Pd(II) complex [PdCl 2( L2)] supported on silica undergoes a clear color change upon exposure to ethylene, while remaining stable toward air and water, and forms the basis for new simple colorimetric detectors with potential applications in ethylene pipe-leak detection and the monitoring of fruit ripening. Encouragingly, the detector is able to discriminate between fruit at different stages of ripening. The response of the detector to other volatiles was also examined, and specific color changes were also observed upon exposure to aromatic acetylenes. The crystal structures of four new derivatives, including the ethylene-Pt(II) complex [PtCl 2(C 2H 4)( L2)], are also described.

The trifluorovinyl phosphine complexes [Cp*RhCl 2 {PR 3− x (CF CF 2 ) x }] ( 1 x = 1, a R = Ph, b Pr i , c Et; 2 x = 2, R = Ph) have been prepared by treatment of [Cp*RhCl(μ-Cl)] 2 with the relevant phosphine. The salt [Cp*RhCl(CNBu t ){PPh 2 (CF CF 2 )}]BF 4 , 3 , was prepared by addition of Bu t NC to 1a in the presence of NaBF 4 . The salt [Cp*RhCl{κP,κS-(CF 2 CF)PPh(C 6 H 4 SMe-2)}]BF 4 was prepared as a mixture of cis ( 5a ) and trans ( 5b ) isomers by treatment of [Cp*RhCl(μ-Cl)] 2 with the phosphine-thioether (CF 2 CF)PPh(C 6 H 4 SMe-2), 4 , in the presence of NaBF 4 . The structures of 1a – c and 5a have been determined by single-crystal X-ray diffraction. Intramolecular dehydrofluorinative carbon–carbon coupling between pentamethylcyclopentadienyl and trifluorovinylphosphine ligands of 1a , 3 and 5 has been attempted. No reaction was observed on treatment of the neutral complex [Cp*RhCl 2 {PPh 2 (CF CF 2 )}], 1a , with proton sponge, however, 5a underwent dehydrofluorinative coupling to yield [{η 5 ,κP,κS-(C 5 Me 4 CH 2 CF CF)PPh(C 6 H 4 SMe-2)}RhCl]BF 4 , 6 . Other reactions, in particular addition of HF across the vinyl bonds of 5 , occurred leading to a mixture of products. The cation of 3 underwent similar reactions.

The reaction in water of M(II) [M = Ni or Mn] with 1,10-phenanthroline (phen) and sodium pyrophosphate (Na4P2O7) in a 2:4:1 stoichiometry resulted in the crystallization of dinuclear complexes featuring the heretofore rare bridging pyrophosphate. Single-crystal X-ray diffraction studies revealed the complexes to be {[(phen)2Ni]2(μ-P2O7)}·27H2O (1) and {[(phen)2Mn]2(μ-P2O7)}·13H2O (2) where the asymmetric M(phen)2 units are bridged by bis-bidentate pyrophosphate, each metal ion exhibiting a distorted octahedral geometry. The bridging pyrophosphate places adjacent metal centers at 5.031 A in 1 and 4.700 A in 2, and its conformation also gives rise to an intramolecular π−π interaction between two adjacent phen ligands. Intermolecular π−π interactions between phen ligands from adjacent dinuclear complexes create an ornate 3D network in 1, whereas a 2D sheet results in 2. The hydrophilic nature of the pyrophosphate ligand leads to heavy hydration with the potential solvent-accessible area for 1 and 2 accountin...

The interactions of ions in the solid state for a series of representative 1,3-dialkylimidazolium hexafluorophosphate salts (either ionic liquids or closely related) have been examined by crystallographic analysis, combined with the theoretical estimation of crystal-packing densities and lattice-interaction energies. Efficient close-packing of the ions in the crystalline states is observed, but there was no compelling evidence for specific directional hydrogen-bonding to the hexafluorophosphate anions or the formation of interstitial voids. The close-packing efficiency is supported by the theoretical calculation of ion volumes, crystal lattice energies, and packing densities, which correlated well with experimental data. The crystal density of the salts can be predicted accurately from the summation of free ion volumes and lattice energies calculated. Of even more importance for future work, on these and related salts, the solid-state density of 1,3-dialkylimidazolium hexafluorophosphate salts can be pred...

Ruthenium, rhodium, and iridium piano stool complexes of the pentafluorophenyl-substituted diphosphine (C6F5)2PCH2P(C6F5)2 (2) have been prepared and structurally characterized by single-crystal X-ray diffraction. The Cp-P tethered complex [{(C5Me4CH2C6F4(C6F5)CH2P(C6F5)2}RhCl2] (9), in which only one phosphorus is coordinated to the rhodium, was prepared by thermolysis of a slurry of [Cp*RhCl(-Cl)]2 and 2 and was structurally characterized by single-crystal X-ray diffraction. The tethering occurs by intramolecular dehydrofluorinative coupling of the pentamethylcyclopentadienyl ligand and P,P-coordinated 2. The geometric changes that occur on tethering force dissociation of one of the phosphorus atoms. The effects of introducing phosphine ligands to the coordination sphere of piano stool hydrogen transfer catalysts have been studied. The complexes of fluorinated phosphine complexes are found to transfer hydrogen at rates that compare favorably with leading catalysts, particularly when the phosphine and cyclopentadienyl functionalities are tethered. The highly chelating Cp-PP complex [(C5Me4CH2-2-C5F3N-4-PPhCH2CH2PPh2)RhCl]BF4 (1) was found to outperform all other complexes tested. The mechanism of hydrogen transfer catalyzed by piano stool phosphine complexes is discussed with reference to the trends in activity observed.

The purpose of this study is to demonstrate the rational design and behaviour of the first dual-mode optical and chemical prodrug, exemplified by an acetyl salicylic acid-based system.A cyclic 1,4-benzodioxinone prodrug was synthesised by reaction of 3,5-dimethoxybenzoin and acetyl salicoyl chloride with pyridine. After purification by column chromatography and recrystallization, characterization was achieved using infrared and NMR spectroscopies, mass spectrometry, elemental analysis and single crystal X-ray diffraction. Light-triggered drug liberation was characterised via UV-visible spectroscopy following low-power 365 nm irradiation for controlled times. Chemical drug liberation was characterised via UV-visible spectroscopy in pH 5.5 solution.The synthetic method yielded pure prodrug, with full supporting characterisation. Light-triggered drug liberation proceeded at a rate of 8.30x10(-2) s-1, while chemical, hydrolytic liberation proceeded independently at 1.89x10(-3) s-1. The photochemical and hydrolytic reactions were both quantitative.This study demonstrates the first rational dual-mode optical and chemical prodrug, using acetyl salicylic acid as a model, acting as a paradigm for future dual-mode systems. Photochemical drug liberation proceeds 44 times faster than chemical liberation, suggesting potential use in drug-eluting medical devices where an additional burst of drug is required at the onset of infection.

A Povarov reaction, between an aromatic imine derived from cinnamaldehyde and a cyclic enamide, was employed to rapidly construct the tricyclic core of the alkaloids martinelline and martinellic acid. The cycloaddition was completely regioselective though the exo/endo selectivity was poor. The diastereoisomers were readily separated by flash chromatography and the relative stereochemistry of the exo-isomer confirmed by single crystal X-ray crystallography. This intermediate was converted to the central core of the aforementioned alkaloids in five additional synthetic operations.

The pentafluorophenyl-substituted diphosphine (C6F5)PhPCH2CH2PPh(C6F5) has been prepared, as a 1:1.7 mixture of rac (la) and meso (1b) isomers, in four steps from dppe. The reaction between [Cp*RhCl-(μ-Cl)] 2 and 1 in the presence of tetrafluoroborate yielded a mixture of racemic diastereoisomers of [Cp*RhCl(κP,κP-la)][BF4] (4a·BF 4 ) and trans and cis isomers of [Cp*RhCl(κP,κP-1b)][BF 4 ] (4b·BF 4 and 4c·BF 4 , respectively). On addition of Proton Sponge, 4a and 4c, in which at least one pentafluorophenyl group is close to the pentamethylcyclopentadienyl ligand, underwent rapid dehydrofluorinative carbon-carbon coupling giving trans- and cis-[{η 5 ,κP,κP-C 5 Me 4 CH 2 C 6 F 4 -2-PPhCH 2 CH 2 PPh(C 6 F 5 )}RhCl]+ (5 and 6), respectively. The latter underwent further dehydrofluorinative carbon-carbon coupling to give two isomers of [{η 5 ,κP,κP-C 5 Me 3 [CH 2 C 6 F 4 -2-PPhCH 2 ] 2 }RhCl]+ (7). Isomerization of 4b to 4c was observed in chloroform and dimethlysulfoxide. Neither isomerization of 4a to 4b or 4c nor isomerization of 5 to 6 was observed at ambient or elevated temperature in dimethyl sulfoxide. The results provide the first evidence that complexes of η 5 ,κ P ,κL-cyclopentadienyl-phosphine-donor ligands are configurationally stable at high temperature.

Metastable [(phen)2CuCO3]·11H2O, 1, crystallises in P-1 and undergoes a crystal-to-crystal phase transition, giving [(phen)2CuCO3]·7H2O, 1a, in P21/c. Intermolecular π-π interactions between the complexes generate 2-D lattices with (6,3) topology, ‘brick-like’ in 1 and herringbone in 1a; a transition that requires a remarkable 180° rotation (a molecular back-flip) of adjacent [(phen)2CuCO3] units to have occurred during the phase change.

A concise and convergent route to combretastatin D2 is described together with some preliminary biological data.

There is a general lack of understanding of how coordination polymers (metal-organic frameworks) form. Some insight can be gained from observations of formal ROP (ring-opening polymerisation) relationships between coordination polymers and their discrete soluble precursors. Most ROP examples reported previously have involved bidentate bridging ligands. Here we present an unusual example of a ROP relationship based on a tripodal ligand. In particular, 1,3,5-tris(diphenylphosphino)benzene (L1) is found to form a symmetrical coordination cage of stoichiometry Ag3(L1)2 in solution in acetonitrile. This contrasts with previous observations in less-coordinating solvents in which higher nuclearity cages are also formed, and shows that the coordinating acetonitrile solvent reduces anion-templating effects. On crystallization from acetonitrile a one-dimensional polymeric structure [Ag3(L1)2(NCCH3)(OTf)3] n is obtained. The structure is noteworthy in being a ROP isomer of the trinuclear cage observed in solution. The structure also exhibits solvent-filled channels (maximum diameter 6.1 A) but the material is not stable to desolvation. The structure of the polymer contrasts with that obtained from less-coordinating solvents, the latter being a stable hexagonal 2-dimensional structure with nanoporosity.

Tris-chelate 5-hydroxymethyl-2,2′-bipyridine complexes of ruthenium (II) and the structurally related benzo- and naphthoesters have been isolated. The mer-isomer of the alcohol functionalised complex has been isolated by selective precipitation from methylene chloride and was subsequently functionalised to the benzoester with retention of the geometrical isomerism. The fac- and mer-isomeric forms of the ester complexes were separated using preparative plate silica chromatography and characterised by 1H NMR spectroscopy. X-ray structural analysis of the fac-isomer of both the ester complexes confirmed the product assignment. The photophysical properties of the three isomers were investigated, indicating very similar absorption spectra to [Ru(bipy)3]2+. The emission wavelength was comparable in each case, with the aromatic ester complexes giving a much longer lifetime and higher quantum yields

[reaction: see text] The macrocyclic cyclen conjugates 1-4 were synthesized with the aim of forming lanthanide ion-based macrocyclic conjugates possessing deep cavities, formed upon complexation to various lanthanide ions. These complexes all possess metal-bound water molecules, where the pKa of the water molecules depends on the nature of the cavity.

Conformationally flexible NUPHOS-type diphosphines have been resolved as their diastereopure platinum BINOLate complexes δ- and λ-[(NUPHOS)Pt{(S)-BINOL}] and the corresponding enantiopure Lewis acids δ- and λ-[(NUPHOS)Pt(OTf)2], being generated by protonation with trifluoromethanesulfonic acid, act as highly efficient catalysts for the hetero-Diels−Alder reaction of nonactivated conjugated dienes with aryl glyoxals and glyoxylate esters, giving ee's as high as 99%.

A new metal-organic framework Mn(INA)2 (INA=isonicotinate, 4-NC5H4CO2−) was synthesised and found by X-ray crystallography to have pyridine rings arranged in an ordered fashion, leaving cavities sufficiently large for ethanol inclusion. This contrasts with the previously reported iron analogue, which was characterised as disordered and without included guests. The Mn compound may be desolvated whilst remaining crystalline. The results suggest that the rotational freedom of aromatic groups of metal-organic frameworks should be taken into consideration in predicting their available volumes and inclusion characteristics.

The synthesis of a new bis(2,2′-bipyridine), bridged by a Schiff base cyclohexane moiety is described. Surprisingly, this compound does not appear to form discrete oligonuclear metal complexes on the addition of zinc(II) and iron(II) cations. In order to rationalise this behaviour, the compound’s conformation has been explored using a combination of circular dichroism, X-ray crystallography and DFT calculations, indicating that at least two energy barriers need to be overcome to orientate the ligand in a suitable conformation to permit the formation of coordination helicates with control over the metal centred stereochemistry.

The benzaldehyde functionalized phosphine Ph2PC6H4CHO-2 underwent reaction with [(η5-C5Me5)MCl(μ-Cl)]2 (M=Rh, Ir) to form (η5-C5Me5)MCl2(κP-Ph2PC6H4CHO-2), which underwent activation of the aldehyde C–H bond to form (η5-C5Me5)MCl(κP,κC-Ph2PC6H4CO-2). Formally the reaction involves oxidative addition of C–H across the metal and reductive elimination of HCl. The structure of (η5-C5Me5)RhCl(κP,κC-Ph2PC6H4CO-2) has been determined by single-crystal X-ray diffraction.

The properties of the 1-butyl-3-methylimidazolium salt of the dinuclear μ4-(O,O,O‘,O‘-ethane-1,2-dioato)bis[bis(nitrato-O,O)dioxouranate(VI)] anion have been investigated using electrochemistry, single-crystal X-ray crystallography, and extended X-ray absorbance fine structure spectroscopy: the anion structures from these last two techniques are in excellent agreement with each other. Electrochemical reduction of the complex leads to the a two-electron metal-centered reduction of U(VI) to U(IV), and the production of UO2, or a complex containing UO2. Under normal conditions, this leads to the coating of the electrode with a passivating film. The presence of volatile organic compounds in the ionic liquids 1-alkyl-3-methylimidazolium nitrate (where the 1-alkyl chain was methyl, ethyl, propyl, butyl, pentyl, hexyl, dodecyl, hexadecyl, or octadecyl) during the oxidative dissolution of uranium(IV) oxide led to the formation of a yellow precipitate. To understand the effect of the cation upon the composition a...

A thorough and detailed study of diastereointerconversion in the chiral platinum complexes [(NUPHOS)Pt{(S)-BINOL}] (3a−e) has been undertaken and compared with the results of a similar study with [...

A 2,6 pyridino-linked aminocryptand acts as a good host for carboxylate anions, oxalate, malonate, acetate and lactate at low protonation levels as shown by aqueous complexation constants. With oxalate, at the hexaprotonated level of the host, the crystal structure shows formation of a dimeric unit linked by an oxalate/semioxalate short (2.474 A) H-bond. The protonated cryptand uses a cleft-binding mode in preference to the cavity-binding mode used by other aminocryptand hosts.

The synthesis of several lanthanide complexes from the tris alkylated cyclen (1,4,7,10-tetraazacyclododecane) ligands 1 and 2 is described. The syntheses of 1 and 2 were investigated by means of two different synthetic routes (Method 1 and Method 2). The first of these involves the mono protection of cyclen using 4-methoxyphenylsulfonyl chloride, followed by alkylation of the remaining three secondary amines of cyclen, and deprotection using solvated Na(s). Using this approach only 1 was successfully formed. The X-ray crystal structure of the intermediate, 9 and the corresponding La(III) complex, 9.La is presented. The second method involved the direct synthesis of the two ligands in a single step. The X-ray crystallography of the Eu(III) complex of one of these ligands is presented. Whereas, Method 1 yielded the product 1 in high purity, but in low overall yield, Method 2 gave higher yields for both ligands (∼50% for both).

The salt (η5-pentamethylcyclopentadienyl){bis(pentafluorophenyl)thiomethylphenylphosphine-κ2S,P)chloroiridium(III) tetrafluoroborate, [(η5-C5Me5)IrCl{κ2S,P-(C6F5)2PC6H4SMe-2}]BF4, crystallizes as a conglomerate in the orthorhombic crystal system in space group P212121 with unit cell parameters a = 9.9621(9) A, b = 16.7793(15) A, c = 18.5040(16) A, V = 3093.1(5) A3, Z = 4, dcalc = 2.014 g·cm−3. The structure of the SIr, SS stereoisomer reveals three-legged piano stool geometry about Ir, with Cp*-Ir, Ir-P, Ir-S and Ir-Cl distances of 1.847(5) A, 2.2791(14) A, 2.3451(13) A, and 2.3840(12) A respectively.

The structures of three long alkyl chain imidazolium chloride salts have been determined by X-ray diffraction; one of the salts was isolated as two polymorphs. These compounds consist of regions containing interdigitated linear alkyl chains alternating with regions containing imidazolium headgroups, chloride ions, and solvent. The arrangement of the cation headgroup and the alkyl chain is strongly dependent on the thermal history of the salt and whether the C(2) position on the imidazolium ring is methylated or protiated. Structures are found where the headgroups within the same crystal are in different environments leading to a double bilayer structure which collapses on heating.

The ligand N , N -bis[[6-(hydroxymethyl)pyridine-2-yl]methyl]- p -tosylamide ( L ) and its Fe(II), Co(II), Ni(II), Cu(I), Cu(II) and Zn(II) complexes were synthesised as potential catalysts for the hydrolysis of phosphate diesters such as 2-hydroxypropyl p -nitrophenyl phosphate (HPNP) and mRNA. The ligand and its complexes were characterised by X-ray crystallography, IR, fluorescence and absorption spectroscopy and ESMS. The X-ray structures of L · Fe(II) , [L 1 Fe 1 ] , L · Co(II) [L 1 Co 1 ] , L · Ni(II) [L 1 Ni 1 ] and L · Zn(II) [L 1 Zn 1 ] showed that there were structurally similar complexes consisting of an octahedral geometry where the metal ion was coordinated to the nitrogens of the two pyridines and to the two hydroxy groups in a square planar arrangement with two CH 3 CN molecules capping the two vacant coordination sites. The L · Cu(II) however was obtained as a symmetrical dimer [L 2 Cu 2 ] from Cu(I). The recognition (complexation) of the in situ complex L · Cu(I) (which gave L · Cu(II) upon oxidation in air) and L · Zn(II) were also investigated by monitoring the changes in the 1 H NMR spectrum upon titration with Cu(I) and Zn(II) salts. The L · Zn(II) complex was also strongly fluorescent, with a fluorescence enhancement of ca. 200 upon the addition of 1 eq. of ZnClO 4 . All the compounds hydrolytically cleaved HPNP at pH 7.4 and 37.4 °C, but to different degrees, with L · Cu(II) and L · Zn(II) being most efficient in promoting transesterification of HPNP.

The synthesis of four lanthanide ion complexes Eu•1, Eu•2, Tb•1 and Tb•2, from the heptadentate tri-arm cyclen (1,4,7,10-tetraazacyclododecane) ligands 1 and 2 that were made in one-pot syntheses is described. These coordinatively unsaturated complexes have two labile metal-bound water molecules, as demonstrated by X-ray crystallography. This was also confirmed by evaluating their hydration state (q∼2) by measuring their lifetimes in D2O and H2O, respectively. The above complexes were all designed as being “photophysically silent” prior to the recognition of the anion, since they do not possess antenna that can participate in sensitisation of the Eu(III) or the Tb(III) excited state. However, the two water molecules can be displaced upon anion binding by the appropriate aromatic carboxylates to give ternary complexes in water, through either four- or six-member ring chelates (q∼0), or possibly via a monodentate binding. In the case of Tb•1 and Tb•2, large luminescence enhancements were observed upon the f...

[structure: see text] Palladium and platinum complexes of conformationally flexible 1,3-butadiene-bridged diphosphines NUPHOS can be resolved with (S)-BINOL at elevated temperatures to afford diastereopure delta-[(NUPHOS)M[(S)-BINOL]] (M = Pd, Pt). The homochiral Lewis acid complexes delta-[(NUPHOS)M][OTf](2), generated by protonation of delta-[(NUPHOS)M[(S)-BINOL]] with trifluoromethanesulfonic acid, catalyze the Diels-Alder reaction between acryloyl-N-oxazolidinones and cyclopentadiene to give ee values up to 96%. The corresponding enantiopure dichlorides delta-[(NUPHOS)PtCl(2)] react with AgClO(4) to form highly efficient catalysts that give good endo/exo selectivities and high endo enantioselectivity.

The tetrafluoropyridyl-substituted diphosphine Ph 2 PCH 2 CH 2 PPh(C 5 F 4 N-4) (1) has been prepared in three steps from dppe. Comparison of the spectroscopic properties between trans-[RhCl(CO)(PPh 2 (C 5 F 4 N-4)} 2 ] and analogous complexes of other fluorinated triaryl phosphines reveals the lower basicity of tetrafluoropyridylphosphines relative to pentafluorophenylphosphines. The reaction between [Cp*RhCl(μ-Cl)] 2 and 1 in the presence of [BF 4 -] yielded racemic diastereoisomers of [Cp*RhCl( 1 )] [BF 4 ]. In the S R h R p and R R h S p pair of enantiomers the C p * and tetrafluoropyridyl groups have a cis disposition about the Rh-P bond, and in the S R h S p and R R h R p pair the groups are trans. In situ NMR experiments reveal that the cis pair, in which the C p * and tetrafluoropyridyl groups are close, underwent rapid dehydrofluorinative C-C coupling to give the respective enantiomers of [{η 5 ,κP,κP -C 5 Me 4 CH 2 - 2 -C 5 F 3 N-4-PPhCH 2 -CH 2 PPh 2 }RhCl][BF 4 ] (6.[BF 4 ]). The trans pair did not undergo coupling, but isomerized to the cis pair on heating in ethanol. The reaction between [Cp*RhCl(μ-Cl)] 2 and 1 in refluxing benzene afforded 6.[BF 4 ] in 64% yield after anion metathesis. The structures of OPPh 2 -(C 5 F 4 N-4), the cis isomer of [Cp*RhCl(1)][BF 4 ], and one enantiomer of 6.[BF 4 ], which crystallizes as a conglomerate, have been determined by single-crystal X-ray diffraction.

We report herein the single crystal structures of 4,4′-dicarboxy-2,2′-bipyridine, H2dcbp, and two complexes it forms with Co(II), [Co(dcbp)(H2O)4]·4H2O, 1, and Cu(II), {[Cu(dcbp)(H2O)2]·2H2O}n, 2. H2dcbp adopts the anti conformation in the solid-state, with a dihedral angle of 148° between each pyridyl ring. Face-to-face π⋯π interactions reinforce intermolecular hydrogen bonding (O–H⋯N) involving both carboxylate oxygen and pyridyl nitrogen atoms forming a 2D inter-helical network. Alternate 2D layers are of opposite chirality and are linked into 3D through (C–H⋯O) hydrogen bonds. In both 1 and 2 the ligand is deprotonated giving neutral complexes with 1 ∶ 1 stoichiometry. Although 1 is monomeric, extensive hydrogen bonding between the deprotonated carboxylates, lattice water, and coordinated water molecules results in a 3D network which also contains face-to-face π⋯π interactions between adjacent dcbp ligands. Within 2, pseudo-octahedral coordination about the Cu(II) centre is furnished by bidentate bipyridyl nitrogens, two monodentate carboxylates (from two adjacent dcbp ligands) and two water molecules. Coordination of dcbp in this instance forms a 2D coordination polymer, which is further linked by extensive hydrogen bonding between carboxylates and water molecules, giving a 3D network.

The glycine–alanine conjugated ligands of cyclen (1,4,7,10,-tetraazacyclododecane) 1 and 2, possessing methyl and benzyl alanine esters respectively, and the corresponding lanthanide complexes 1La, 1Eu, 1Tb, 1Yb, 2La, 2Eu, and 2Tb were designed with the aim of mimicking the nature of the hydrophobic cavity of ribonucleases. X-ray crystallographic investigations showed that 2Tb has a typical monocapped square antiprism geometry, where the Tb(III) ion is central, coordinating to the four amino moieties of the cyclen ring and four of the oxygens of amide carbonyl groups of the glycine residues of the four pendant arms, with the ninth coordinated site being occupied by a water molecule. All the complexes were shown to promote the hydrolysis of the phosphodiester bond of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP, τ1/2=5.78×103 h) with 1Tb being the most efficient in promoting such hydrolysis at pH 7.4 and at 37 °C for the 1Ln family with τ1/2=4.9 h. For the 2Ln family, 2La was most effective in promoting hydrolysis of HPNP, with τ1/2=3.7 h. The rate of hydrolysis was also investigated for 1La and 2La as function of pH, with both complexes displaying bell-shaped pH dependence within the physiological pH range. For 1Ln the highest activity was observed at pH 7.0, with τ1/2=4.6 h, whereas for 2La it occurred at pH 7.4. Beyond pH 8, the rate of both complexes was shown to be almost linearly increased. The ability of 1Eu and 2Eu to cleave a 23-mer sequence from the mRNA of the GAG–HIV gene was also investigated. It was found that both gave rise to cleavage of the sequence at every nucleotide residue after 4 h of incubations at pH 7.4 and 37 °C.

In chloroform, [RuCl2(nbd)(py)2] (1) (nbd = norbornadiene; py = pyridine) reacts with 1,4-bis(diphenylphosphino)-1,2,3,4-tetramethyl-1,3-butadiene (1,2,3,4-Me4-NUPHOS) to give the dimer [Ru2Cl3(η4-...

The ability of four polymorphic compounds, isonicotinamide (1), 2-amino-3-nitropyridine (2), 4-chlorobenzamide (3), and maleic hydrazide (4), to form molecular cocrystals has been examined in a systematic structural study. Compounds 1−3 participate in a wide variety of binary and ternary (in the case of 1) cocrystals with aromatic or aliphatic compounds substituted with a multitude of functional groups. However, despite considerable efforts, it has not been possible to form any cocrystals with 4. The reason for this may be due to the fact that even though there are three known polymorphs of 4, they all contain the same hydrogen-bonding synthons. In contrast, the polymorphs of 1−3 display considerable synthon flexibility, e.g., different hydrogen bond interactions are present in polymorphs of the same compound. Because 1−3 can form robust synthons in a variety of ways, whereas 4 always engages in the same primary hydrogen bond interactions, it may explain why the former compounds are readily able to accomm...

Treatment of 1,2,3,4-tetrafluorodibenz[ b , f ][1,4]oxazepine with acetyl or benzoyl chloride produces the fluorinated aryl ethers bearing amide and aldehyde functionalities, RCONHC 6 H 4 -2-OC 6 F 4 CHO-2 ( 2a R=Ph; 2b R=Me). The structures of intermediate compounds produced by addition of acid chloride across the imine bond and by partial hydrolyis of the resulting chlorine-containing compound have been determined.

The reaction in water of Cu(OH)2 with 2,2′-bipyridine (bipy) and (NH4)2HPO4 (4 ∶ 4 ∶ 2) in air leads to the formation of two structurally related complexes following the fixation of CO2: {[(H2O)2Cu4(bipy)4(μ4-PO4)2(μ2-CO3)]·22.5H2O}, 1, and {[(H2O)2Cu4(bipy)4(μ4-PO4)2(μ2-CO3)]·15.5H2O}, 1a, as determined by single crystal X-ray diffraction. Whilst each complex contains isostructural tetranuclear Cu(II) butterfly cores, they differ in the way they pack in the solid state: adjacent units in 1 align in parallel fashion, whereas those in 1a form H-bonded dimers in an antiparallel arrangement. 1 and 1a are therefore supramolecular isomers. 1 is encapsulated within an ‘ice-like’ 3D H-bonded water network whereas the solvent sheath about 1a forms a 2D H-bonded network. A similar product results when bipy is replaced with 1,10-phenanthroline (phen) giving {[(H2O)2Cu4(phen)4(μ4-PO4)2(μ2-CO3)]·21.5H2O}, 2, which possesses an isostructural butterfly core shrouded within a 3D H-bonded water network. 2 packs in the solid-state in a similar way to 1 although, in this instance, adjacent units align in an antiparallel fashion. Both 1 and 2 may be directly synthesised in higher yields when (NH4)HCO3 is included within the reaction medium. A magnetic susceptibility study performed upon 1 reveals net weak intramolecular antiferromagnetic coupling between the Cu(II) centres.

[EN] A wide range of room temperature ionic liquids based on the 3-methylpiperdinium cation core were produced from 3-methylpiperidine, which is a derivative of DYTEKs (R) A amine. First, reaction with 1-bromoalkanes or 1-bromoalkoxyalkanes generated the corresponding tertiary amines (Rm beta pip, R = alkyl or alkoxyalkyl); further quaternisation reactions with the appropriate methylating agents yielded the quaternary [Rmm(beta)pip]X salts (X-= I-, [CF3CO2]-or [OTf](-); Tf = -SO2CF3), and [Rmm(beta)pip][NTf2] were prepared by anion metathesis from the corresponding iodides. All [NTf2]-salts are liquids at room temperature. [Rmm(beta)pip]X (X-= I-, [CF3CO2]-or [OTf](-)) are low-melting solids when R = alkyl, but room temperature liquids upon introduction of ether functionalities on R. Neither of the 3-methylpiperdinium ionic liquids showed any signs of crystallisation, even well below 0 degrees C. Some related non-C-substituted piperidinium and pyrrolidinium analogues were prepared and studied for comparison. Crystal structures of 1-hexyl-1,3-dimethylpiperidinium tetraphenylborate, 1-butyl-3-methylpiperidinium bromide, 1-(2-methoxyethyl)1- methylpiperidinium chloride and 1-(2-methoxyethyl)-1-methylpyrrolidinium bromide are reported. Extensive structural and physical data are collected and compared to literature data, with special emphasis on the systematic study of the cation ring size and/or asymmetry effects on density, viscosity and ionic conductivity, allowing general trends to be outlined. Cyclic voltammetry shows that 3-methylpiperidinium ionic liquids, similarly to azepanium, piperidinium or pyrrolidinium counterparts, are extremely electrochemically stable; the portfolio of useful alternatives for safe and high-performing electrolytes is thus greatly extended., We would like to acknowledge the EPSRC NCS in Southampton for the single crystal X-ray diffraction data collection and INVISTA Intermediates for funding.

The structure of liquid 1, 3-dimethylimidazolium hexafluorophosphate is described in detail and compared with the structure of 1, 3-dimethylimidazolium chloride. In each case, the data were obtained from neutron diffraction experiments and analysed using an empirical potential structure refinement process. Overall, the structures are similar; however, significant differences arise from the variation in anion size.

The rhodium(III) complex [Cp*RhCl(dfppe)]BF4, 1, undergoes rapid stepwise intramolecular dehydrofluorinative carbon−carbon coupling on addition of proton sponge to produce [{η5,κP,κP-C5Me3[CH2C6F4-2-P(C6F5)CH2]2-1,3}RhCl]BF4. The reaction requires less than the stoichiometric quantity of proton sponge and also occurs on addition of Bun4NF or in the presence of polymer-supported fluoride. NMR studies of reactions between a series of complexes and proton sponge have revealed the necessary conditions for intramolecular dehydrofluorinative coupling in pentamethylcyclopentadienyl rhodium(III) phosphine complexes. The complex must be cationic, and the phosphine, which can be either part of a chelating ligand or monodentate need have only one pentafluorophenyl substituent. The reaction is rapid where Cp* and C6F5 are held in close proximity. The compounds [Cp*RhCl{(C6F5)2PC6H4SMe-2}]BF4, 7, and the diastereoisomer of [Cp*RhCl{(C6F5)PhPC6H4SMe-2}]BF4, 11a, in which Cp* and C6F5 are cis, undergo rapid coupling on ...

The syntheses of the bis-aromatic 15-crown-5 and 18-crown-6-ether derivatives 1 and 2, for the selective recognition of intra- and extracellular concentrations of Na+ and K+, from o-anisidine are described. These compounds were made with the aim of incorporating them into luminescent sensors. To facilitate their incorporation into such sensors, the compounds were nitrated. Whereas the use of conventional nitration reagents such as HNO3, HNO3–H2SO4 or NO2BF4 only gave low yields of the desired products, both mono- and bis-nitration products were formed in good yield by one-pot synthesis using NaNO2 in a mixture of water and acetic acid (10 ∶ 1). The use of X-ray crystallography proved the presence of the nitro-substituted products. An investigation into this mild nitration method revealed that the substitution pattern on the aromatic ring governed the ability of the compounds to undergo nitration.

We present here two different topologies that result from the bis-bidentate ligand bis(pyridine-4,4‘-diaminodiphenyl)methane, L, upon coordination to Cu(I) or Cu(II), namely, a metallo-cyclophane or “molecular-box” [Cu2L2(ClO4)2]·4(MeCN)·2(EtOH), 1, and a helicate [Cu2L3(ClO4)4]·3(MeCN), 2, and show that metal ion coordination preference is the major determinant in defining which topology results.

Zirconium-mediated inter- and intramolecular reductive cyclization of alkynes and diynes has been used to prepare a new class of bidentate phosphine, based on a four-carbon sp2-hybridized tether. Intermolecular coupling of diphenylacetylene and but-2-yne with Negishi's reagent followed by transmetalation with copper chloride prior to quenching with chlorodiphenylphosphine affords the corresponding acyclic diphosphines 1,4-bis(diphenylphosphino)-1,2,3,4-tetraphenyl-1,3-butadiene (2a; 1,2,3,4-Ph4-NUPHOS) and 1,4-bis(diphenylphosphino)-1,2,3,4-tetramethyl-1,3-butadiene (2b; 1,2,3,4-Me4-NUPHOS), respectively. A single-crystal X-ray analysis of the former has been obtained. Surprisingly, 1-phenylpropyne undergoes a highly regioselective reductive cyclization to afford 1,4-bis(diphenylphosphino)-1,3-diphenyl-2,4-dimethyl-1,3-butadiene (2c; 1,3-Ph2-2,4-Me2-NUPHOS). Similarly, transmetalation of the zirconacyclopentadiene generated from 3,9-dodecadiyne and 1,8-diphenyloctadiyne followed by electrophilic liberatio...

The NMR and crystallographic characterization of lithium bis[salicylato(2-)]borate, Li(BSB), and lithium bis[1,2-benzenediolato(2-)-O,O‘]borate, Li(BBB), are reported. The single-strand polymer {(MeCN)2 Li(BSB)}∞ crystallizes from a saturated solution of Li(BSB) in ethanenitrile and consists of μ2-{(MeCN)2Li}+ cations bridging the exocyclic oxygen atoms of two [BSB]- anions. Crystallization of Li(BSB) from tetrahydrofuran produces {(THF)2Li(BSB)}∞, which has essentially the same structure as {(MeCN)2Li(BSB)}∞. In contrast, crystals of Li(BBB) grown from THF/diethyl ether or THF/toluene mixtures (1:1) contain adventitious water and form a hydrogen-bonded, three-dimensional lattice comprising {(H2O)2(THF)Li(BBB)} units. This novel structural motif contains the first example of lithium bound to one THF and two water molecules, and also exhibits hydrogen bonding between the water and the THF. Ab initio calculations suggest that the Li−OBBB bond in {(H2O)2(THF)Li(BBB)}∞, while still predominantly ionic in char...

A series of long-chain 1-alkyl-3-methylimidazolium salts ([Cn−mim]X, n = 12−18) containing the anions, chloride, bromide, trifluoromethanesulfonate (OTf), and bis(trifluoromethanesulfonyl)imide (TFI), have been synthesized and characterized. The salts have amphiphilic characteristics, and the thermotropic phase behavior of these salts and the analogous tetrafluoroborate salt has been investigated by variable temperature small-angle X-ray scattering, polarizing optical microscopy, and differential scanning calorimetry. The salts form lamellar, sheetlike arrays in the crystalline phase and an enantiomeric smectic liquid crystalline phase at higher temperatures, except for the salts containing the bis(trifluoromethanesulfonyl)imide anion which melt directly to form isotropic liquids. The nature of the anion influences the size of the interlayer spacing in both the crystal and in the mesophase. The interlayer spacing in the mesophase is largest for the anions with the greatest ability to form a three-dimensio...

Treatment of an aqueous suspension of Cu(OH)2 and 2,2′-bipyridine (bipy) with either Na2HAsO4·7H2O (1∶1∶2) or As2O5 (1∶1∶1) yields single crystals of {[(bipy)Cu(μ-H2AsO4)(H2AsO4)]2}n, 1, on standing. The solid-state structure of 1 consists of a three dimensional supramolecular network, supported by a combination of coordination covalent, hydrogen bonding and face-to-face π–π interactions. Variable temperature magnetic susceptibility measurements reveal very weak antiferromagnetic coupling between Cu(II) centres across the dihydrogen arsenate bridges (J = −0.58 cm−1).

Terminally N-substituted dienes derived from 3-methylisoindolin-1-one, 4-isopropyl- and 4-phenyloxazolidin-2-one undergo Diels–Alder reaction with a range of activated dienophiles. The reactions reported are completely regio- and endo-selective, with the diastereoisomeric excess with respect to the auxiliary good to excellent in most of the cases reported. A model has been developed for rationalising the stereochemical outcome of these reactions.