Gino Bentivoglio

A cytotoxic bis(carbene)gold(I) complex of ferrocenyl complexes: Synthesis and structural characterisation

The N-heterocyclic carbene (NHC) precursors 1-[(E)-2-butenyl]-3-(4-ferrocenylphenyl)imidazolium bromide (2) and 1-[(E)-2-butenyl]-3-(4-ferrocenylphenyl)imidazolium tetrafluoroborate (3) were derived from 1-(4-ferrocenylphenyl)imidazole. Ferrocenyl complex 3 reacts with Ag2O and chloro(dimethylsulfide)gold(I) in the presence of tetraethylammonium chloride to produce the mixed metal species bis{1-[(E)-2-butenyl]-3-(4-ferrocenylphenyl)-2H-imidazol-2-ylidene}gold(I) tetrafluoroborate (4). Single crystal X-ray structure analyses of 1, 3 and 4 indicate that the NCHN-hydrogen in 3 is hydrogen bonded to the BF4− anion [C(H1)⋯F, 3.265(4) A], as is also reflected in the position of its 1H NMR chemical shift. Cytotoxicity studies show that complex 4 is selective for cancer cells and active against the tumour cell lines Jurkat and MCF 7.

Ionic liquids as superior solvents for headspace gas chromatography of residual solvents with very low vapor pressure, relevant for pharmaceutical final dosage forms.

1-n-Butyl-3-methylimidazolium dimethyl phosphate (BMIM DMP) was identified as the most suitable ionic liquid as solvent for the headspace gas chromatographic analysis of solvents with very low vapor pressure such as dimethylsulfoxide, N-methylpyrrolidone, sulfolane, tetralin, and ethylene glycol in a realistic matrix of commonly used excipients (carboxymethylcellulose, magnesium stearate, guar flour, and corn starch) in pharmaceutical products. Limits of quantification and limits of detection were in the low microgram per gram range. The detection of traces of sulfolane in a real sample of tablets containing the drug cefpodoxim proxetil demonstrated the applicability of the method.

N,N'-Di(alkyloxy)imidazolium Salts: New Patent-free Ionic Liquids and NHC Precatalysts

1-Hydroxyimidazole-3-oxides (2-H, 2-Me) were alkylated with (RO)2SO2 (R =Me, Et) to give the new 1,3-di(alkyloxy)imidazolium cations which were isolated as hexafluorophosphates. Ion metathesis yielded new hydrophobic ionic liquids (bis(trifluoromethanesulfonyl)imides, tris(pentafluoroethyl) trifluorophosphates). Bromination afforded 2-bromo derivatives which were converted to Ni and Pd N-heterocyclic carbene complexes by oxidative insertion. Fifteen crystal structures were determined by X-ray diffraction. The N-alkyloxy groups are twisted out of the imidazole ring plane and adopt either syn or anti conformations in the solid state.

Syntheses, crystal structures, and polymorphism of quaternary pyrrolidinium chlorides

The syntheses, properties, and X-ray crystal structures of 1-methyl-1-propylpyrrolidinium chloride1, 1-allyl-1-methylpyrrolidinium chloride2, and 1-methyl-1-propargylpyrrolidinium chloride3 are described. Colorless plates of 1 (C8H18ClN) crystallize in the orthorhombic space groupPnab with Z = 8 and unit cell parameters a = 10.0354(11) A, b = 13.254(2) A, c = 14.6231(16) A. Colorless prisms of 2 (C8H16ClN) crystallize in the monoclinic space groupP21/c with Z = 4 and unit cell parameters a = 6.4857(10) A, b = 12.005(3) A, c = 12.526(2) A, and β=102.746(13)°. Colorless needles of 3 (C8H14ClN) crystallize in the monoclinic space groupP21/n with Z = 4 and unit cell parameters a = 8.4849(14) A, b = 8.1271(16) A, c = 13.501(2) A, and β=100.408(13)°. The five-membered ring adopts a twisted conformation in 1 but an N-envelope in 2 and 3. The salts form networks of weak C–H…Cl−hydrogen bonds. Hot stage microscopy, differential scanning calorimetry and temperature-controlled X-ray powder diffractometry revealed that each of the three compounds exists in at least two different crystal forms.

Synthesis and Crystal Structures of 1-Alkoxy-3-alkylimidazolium Salts Including Ionic Liquids, 1-Alkylimidazole 3-oxides and 1-Alkylimidazole Perhydrates

Abstract Functionalized quaternary imidazolium salts were prepared with the intention to obtain new ionic liquids (ILs). Thus, more than forty 3-alkoxy-1-alkylimidazolium salts, 3-alkoxy-1-alkyl-2-methylimidazolium salts, 1-methylimidazole 3-oxide and 1,2-dimethylimidazole 3-oxide as well as their salts, 1,3-dihydroxyimidazolium salts and 1,3-dihydroxy-2-methylimidazolium salts were synthesized and characterized by spectroscopy and, to a limited extent, by viscosity and conductivity measurements. Results of fourteen single crystal X-ray structure determinations are reported, among them also the parent compounds 1-hydroxyimidazole 3-oxide and 1-hydroxy-2-methylimidazole 3- oxide. Selective debenzylation of 1-benzyloxy-3-methyl imidazolium salts and mono-demethoxylation of 1,3-dimethoxyimidazolium salts were achieved by hydrogenolysis. In addition, a crystalline semiperhydrate of 1,2-dimethylimidazole was characterized. Furthermore, an addition compound of 1-methylimidazole 3-oxide with tris(2-thienyl)borane and a silver carbene complex derived from 1-benzyloxy-3-methylimidazolium hexafluorophosphate was crystallized and characterized.

Crystal structure of Ƞ2-1-allyl-3-methylimidazolium trichloroplatinate( II), [C7H11N2][PtCl3]

C7H11Cl3N2Pt, orthorhombic, P212121 (no. 19), a =7 .6873(2) A, b =1 1.9159(3) A, c =1 2.1398(3) A, V =1 112.0 A 3 , Z =4 , Rgt(F) =0 .018, wRref(F 2 ) =0 .045, T =2 33 K. Source of material Potassium - 2 -ethylene trichloroplatinate(II) hydrate (Zeise’s salt) [CARN: 123334-22-5] was stirred with an equimolar amount of 1-allyl-3-methylimidazolium BF4 [CARN: 85160663-8] [1] for three days at room temperature. The precipitate was collected by filtration, washed with water, and redissolved in DMF. Yellow crystals of the zwitterionic title compound, suitable for X-ray diffraction, were obtained from this solution by diffusion with diethyl ether at −20 °C. Experimental details

Crystal structure of bis( 1 -butyl-3-methylimidazolium) hexachlorotitanate( IV) bis(dichloromethane) solvate, (C8H15N2)2[TiCl6] · 2CH2Cl2

Abstract C18H34Cl10N4Ti, monoclinic, P121/n1 (no. 14), a = 12.8243(4) Å, b = 9.2932(2) Å, c = 14.3634(5) Å, β = 100.572(2)°, V = 1682.8 Å3, Z = 2, Rgt(F) = 0.041, wRref(F2) = 0.112, T = 233 K.