Cobaltoceniumethynyl gold(I) as an unusual heterodinuclear bioorganometallic fragment to study the biological properties of alkynyl gold complexes

A cobaltoceniumethynyl gold(i) complex with a triphenylphosphane ligand triggered efficient cytotoxic effects in cancer cells in contrast to a derivative with two cobaltocenium moieties. The complex effectively inhibited the enzyme thioredoxin reductase (TrxR) suggesting this enzyme as a possible biological target. The cellular uptake of both metal fragments of the active complex was studied by atomic absorption spectroscopy and indicated a high biological stability of the complex.

Zur Reaktion von (COD)PtCl2 mit 1,4-Bis-[di(t-butyl)phosphino]butan (dtbpb). Kristallstruktur von [(t-Bu)2P(CH2)4P(t-Bu)2 – (C8H12) – PtCl]+ Cl- / On the Reaction of (COD)PtCl2 with 1,4-Bis-[di(t-butyl)phosphino]butane (dtbpb). Crystal Structure of [(t-Bu)2P(CH2)4P(t-Bu)2–(C8H12)–PtCl]+Cl-

Whereas (COD)PtCl2 usually reacts with bidentate phosphine ligands under substitution of the COD ligand, the reaction with the newly synthesized 1,4-bis-[di(t-butylphosphino)] butane results in the insertion of COD into one Pt-P bond affording [(t-Bu)2P(CH2)4 P(t-Bu)2-(C8H12)-PtCl]+Cl- (1). 1 crystallizes in the monoclinic space group C2/c with a = 3912.8(8), b = 1765.6(3), c = 3851.3(4) pm, β = 118.36(2)°, Ζ = 24. In the cation of 1 the second C=C bond remains coordinated to the central Pt2+ ion. The square-planar coordination of Pt2+ ion is completed by a Cl ligand and the second P atom of the phosphine ligand. The inserted C-C bond is elongated to 149(5) pm with respect to the coordinating C=C bond of 133(6) pm.

Ionic liquids as advantageous solvents for headspace gas chromatography of compounds with low vapor pressure

The potential of ionic liquids as solvents for headspace gas chromatography was investigated. Three compounds with boiling points above 200 degrees C were selected to demonstrate the feasibility of the concept described. 2-Ethylhexanoic acid, formamide, and tri-n-butylamine as examples of acidic, neutral, and basic analytes were dissolved in acidic 1-n-butyl-3-methylimidazolium hydrogen sulfate (1), neutral 1-n-butyl-2,3-dimethylimidazolium dicyanamide (2), and 2 containing 1,8-diazabicyclo[5.4.0]undec-7-ene to adjust basic conditions. All analytes could be determined with limits of detection and limits of quantification in the low-ppm concentration range.

Crystal structure of dichloro-(3-cyclopentadienyl-3-methyl-1-phenylbutyliden- 2,6-dimethylphenylamino)chromium(III), CrCl2(C24H26N)

C24H26Cl2CrN, monoclinic, P121/c1 (no. 14), a = 11.5168(5) Å, b = 13.9721(6) Å, c = 14.1146(4) Å, β = 104.628(2)°, V = 2197.6 Å3, Z = 4, Rgt(F) = 0.039, wRref(F2) = 0.095, T = 233 K.

Crystal structure of (E)-2-ruthenocenylethenylcobaltocenium hexafluorophosphate, [(C5H5)Ru(C12H10)Co(C5H5)][PF6]

C22H20CoF6PRu, monoclinic, P121/c1 (no. 14), a = 9.9053(2) Å, b = 11.4730(3) Å, c = 18.5156(5) Å, β = 94.940(2)°, V = 2096.4 Å3, Z = 4, Rgt(F) = 0.041, wRref(F2) = 0.094, T = 233 K.

A New Multifunctional Ferrocenyl-Substituted Ferrocenophane Derivative: Optical and Electronic Properties and Selective Recognition of Mg2+ Ions

The synthesis, characterisation, and X-ray structure of a new strained asymmetric diferrocene derivative (2) is reported. Compound 2 acts as a highly specific electrochemical and optical Mg(2+) ion sensor, as revealed by spectroscopic and electrochemical techniques. Thus, in the presence of Mg(2+), a new redox peak appears in the cyclic voltammogram (CV) that is anodically shifted compared to the E(1/2) of the free receptor (DeltaE(1/2)=340 mV). Diferrocene derivative 2 also gives a highly visual response upon addition of Mg(2+), namely a change of colour from orange to deep purple. In addition, compound 2 does not show any significant sensing activity in the presence of Ca(2+) or alkaline ions. On protonation, it is converted into the stable diferrocenylcarbenium salt 4, in which two different modes of stabilisation of the alpha-carbocationic centre are clearly demonstrated by a combination of (1)H NMR and (57)Fe Mössbauer spectroscopic measurements. Finally, by a partial (chemical or electrochemical) oxidation, compound 2 forms the asymmetric mixed-valence species 2(+), which can be isolated as the solid salt 6 by using CF(3)SO(3) (-) as a counterion. This mixed-valence species shows a fast intramolecular electron-transfer process, as ascertained by several spectroscopic techniques.

Synthesis, structural and magnetic properties of a series of copper(ii) complexes containing a monocarboxylated perchlorotriphenylmethyl radical as a coordinating open-shell ligand

A series of complexes of copper(II)-containing a perchlorotriphenylmethyl radical functionalized with a carboxylic group as a new ligand is reported. The compounds [Cu(PTMMC)(2)(L)(3)](PTMMC = (tetradecachloro-4-carboxytriphenyl)methyl radical; L =(1) H(2)O, (2) pyrimidine and ethanol or (3) pyridine), [Cu(2)(PTMMC)(2)(MeCOO)(2)(H(2)O)(2)](4) and [Cu(HPTMMC)(2)(L)(3)](HPTMMC =alpha-H-(tetradecachlorotriphenyl)methane-4-carboxylic acid; L = pyridine)(5) were structurally characterized. In complexes 1, 2, 3, and 5, the copper(II) ion is coordinated to two PTMMC (or HPTMMC) units in a slightly distorted square planar surrounding, while 4 shows a paddle-wheel copper(II) dimer structure, where each Cu metal ion has four O atoms of different carboxylate groups, two of them belonging to two PTMMC radicals. The copper(II)-radical exchange couplings are antiferromagnetic for complexes 1, 2 and 3. A linear three-spin model was applied to complexes 1, 2 and 3 to give J/k(B)=-24.9, -15.0 and -20.7 K, respectively. Magnetic properties of 4 show that it is one of the scarce examples of a spin-frustrated system composed of organic radicals and metal ions. In this case, experimental data were fitted to a magnetic model based on a symmetrical butterfly arrangement to give a copper(II)-copper(II) exchange coupling of J/k(B)=-350.0 K and a copper(II)-radical exchange coupling of J/k(B)=-21.3 K, similar to that observed for the copper(II)-radical interactions in complexes, and.

Bulk Spontaneous Magnetization in the New Radical Cation Salt TM-TTF[Cr(NCS)4(isoquinoline)2] (TM-TTF = Tetramethyltetrathiafulvalene)

A new organic-inorganic hybrid salt [TM-TTF][Cr(NCS)(4)(isoquinoline)(2)] (1) (TM-TTF = Tetramethyltetrathiafulvalene) has been synthesized. Compound 1 crystallizes in the triclinic P space group with a = 8.269(1), b = 10.211(2), and c = 11.176(2) A, alpha = 89.244(9), beta = 88.114(6), and gamma = 74.277(7) degrees, V = 907.6(3) A(3), and Z = 1. The crystal structure was resolved in the temperature range between 223 and 123 K, showing that changes in the crystal structure at low temperature result in stronger interactions between anions and cations. The packing of 1 consists of mixed anion-cation layers in the bc plane containing S.S and pi-pi anion-cation interactions, the layers being connected by very short S.S contacts between anions and cations. Magnetic measurements in a small external field show bulk spontaneous magnetization with a T(c) of 6.6 K consistent with the presence of weakly coupled ferrimagnetic order in compound 1. The EPR measurements also demonstrate the interaction between the d and pi electrons and the presence of an internal magnetic field brought about by the magnetic ordering.

Crystal structure of 1,3,3,4,6,6-hexaferrocenyl-hexa-4,5-dien-1-yne, C66H54Fe6

C66H54Fe6, monoclinic, P121/c1 (No. 14), a = 12.4201(4) Å, b = 20.0247(6)Å, c = 19.8328(3) Å, β = 93.054(2)0, V = 4925.6 Å3, Z = 4, Rgt(F) = 0.039, wRref(F2) = 0.074, T = 223 K.

Crystal structure of [1R,7,7-trimethylbicyclo[2.2.1]heptan-2,3-bis(2,6- diisopropylphen-1-yl)imine]nickeldibromide]—toluene (1:1), C34H48Br2N2Ni · C7H8

C41H56Br2N2Ni, orthorhombic, P212121 (No. 19), a = 10.121(2) Å, b = 17.115(2) Å, c = 22.835(2) Å, V = 3955.5 Å3, Z = 4, Rgt(F) = 0.037, wRref(F2) = 0.086, T = 218 K.

Crystal structure of 14 β-hydroxy-3,4-dimethoxy-5β,17-dimethylmorphinan- 6-one, C20H27NO4

C20H27NO4, monoclinic, P1211 (No. 4), a = 12.689(6) Å, b = 7.539(2) Å, c = 19.490(3) Å, β = 105.87(3)0, V = 1793.4 Å3, Z = 4, Rgt(F) = 0.032, wRref(F2) = 0.081, T = 218 K.

Observation of a P/M interconversion of a gold-phosphine helicate via 31P NMR

Ligands containing P-CH2-CH2-P elements have been shown to form double-stranded helicates whose axis consists of gold atoms with Au...Au contacts; the interconversion of the P and M forms of the helicate [Au3(mu-pp2)2](OTf)3 (pp2 = PhP(CH2CH2PPh2)2) is monitored via 31P NMR.

A highly enantiopure biconcave porphyrin with effective D4-structure

A first representative of an effectively D4-symmetric biconcave porphyrin (1) was prepared from a tetramerizing condensation of a C2-symmetric pyrrole (2). The chiral pyrrole 2 was synthesized in a six-step reaction sequence starting from the C2h-symmetric 2,6-di-tert-butylanthracene. The relevant stereochemistry was introduced in a highly diastereo-discriminating Diels-Alder reaction with fumaric acid di(-)menthyl ester, catalyzed by aluminum chloride. X-ray analyses of two of the dimenthyl esters prepared unambiguously secured their tentatively assigned absolute configuration and that of the pyrrole 2 (as the S,S isomer). The enantiomeric purity of the pyrrole 2 was determined as 99% ee, using the Co11 complex of the porphyrin 1 as a chiral shift reagent. The pyrrole 2 lent itself to a stereochemically nearly uniform preparation of the chiral, biconcave porphyrin 1. Applying Horeau's principle, 1 was calculated to be present in an enantiomeric excess of about 10(9):1. The validity of the statistical considerations relevant for this estimate were verified by examination of the results from preparative tetramerization experiments in which the enantiomeric purity of the pyrrole 2 was deliberately lowered.

Transmission of Magnetic Interactions through an Organometallic Coupler: A Novel Family of Metallocene-Substituted alpha-Nitronyl Aminoxyl Radicals

The capability of metallocene bridges as new organometallic magnetic couplers is evaluated by studying the family of diradicals 2 (M = Fe, Ru) consisting of two purely organic alpha-nitronyl aminoxyl radicals connected by a 1,1'-metallocenylene bridge. Preliminary studies performed with 2-metallocenyl-alpha-nitronyl aminoxyl monoradicals 1 (M = Fe, Ru, Os), as reference compounds, show the presence of a small spin density on the central metal of the metallocenes. This fact makes the metallocene units effective bridges to transmit magnetic interactions by a spin polarization mechanism. The study of the magnetic properties of diradicals 2 in the solid state and in diluted frozen solutions reveals the existence of an intramolecular antiferromagnetic exchange interaction between the radical subunits whose strength is highly dependent on the molecular conformation adopted by the diradical. As shown by crystal data and by ESR measurements, an intramolecular hydrogen bond between the two radical units forces the molecule to adopt a cisoid molecular conformation, which determines that the magnetic interaction occurs by a direct through-space interaction between the two SOMOs of the two radical units along with the classical spin polarization mechanism through the sigma-bonds of the metallocene unit. Lattice constants for both structures are as follows: 1 (M = Fe), C(17)H(21)FeN(2)O(2), a = 7.170(1) Å, b = 10.135(2) Å, c = 10.683(2) Å, alpha = 88.88(3) degrees, beta = 83.42(3) degrees, gamma = 79.75(3) degrees, triclinic, P&onemacr;, Z = 2; 2 (M = Fe), C(24)H(32)FeN(4)O(4), a = 11.848(3) Å, b = 11.785(2) Å, c = 17.728(4) Å, beta = 106.25(2) degrees, monoclinic, P2(1)/n, Z = 4.

Structure of leuconolam sesquihydrate

8a-Ethyl-7,8,8a,10,11,12a-hexahydro-12a- hydroxyindolizino[8,1-ef][1]benzazonine-6,13-(5H,9H)-dione sesquihydrate, C19H22N2O3.3/2H2O, Mr = 353.42, triclinic, P1, a = 9.250 (2), b = 13.366 (3), c = 9.217 (2) A, alpha = 97.786 (3), beta = 119.590 (3), gamma = 70.726 (3) degrees, V = 934.8 A3, Z = 2, Dx = 1.255 g cm-3, Mo K alpha,lambda = 0.71073 A, mu = 0.839 cm-1, F(000) = 378, T = 293 K. The final R value is 0.061 for 1646 significant [I greater than 3 sigma(I)] reflections. The alkaloid from the leaves of Rhazia stricta is built up by a benzene ring ortho disubstituted with a 4,5-dihydro-5-hydroxy-2-oxo-pyrrol-1,4,5-triyl unit and an N(CO)R- unit forming a twelve-membered ring.