The extracellular ligand-binding domain (EPObp) of the human EPO receptor (EPOR) was expressed both in CHO (Chinese Hamster Ovary) cells and in Pichia pastoris. The CHO and yeast expressed receptors showed identical affinity for EPO binding. Expression levels in P. pastoris were significantly higher, favoring its use as an expression and scale-up production system. Incubation of EPO with a fourfold molar excess of receptor at high protein concentrations yielded stable EPO-EPObp complexes. Quantification of EPO and EPObp in the complex yielded a molar ratio of one EPO molecule to two receptor molecules. Residues that are responsible for EPOR glycosylation and isomerization in Pichia were identified and eliminated by site-specific mutagenesis. A thiol modification was identified and a method was developed to remove the modified species from EPObp. EPObp was complexed with erythropoietin (EPO) and purified. The complex crystallized in two crystal forms that diffracted to 2.8 and 1.9 A respectively. (Form 1 and form 2 crystals were independently obtained at AxyS Pharmaceuticals, Inc. and Amgen, Inc. respectively.) Both contained one complex per asymmetric unit with a stoichiometry of two EPObps to one EPO.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The synthesis of [Au(PF3)2][Sb2F11], the first example of a linear, thermally stable metal bis(trifluorophosphine) complex is achieved by CO substitution of [Au(CO)2][Sb2F11] by PF3. The [Au(PF3)2]+ cation can also be generated by reductive phosphorylation by an excess of PF3 in fluorosulfuric acid. Spectroscopic characterization involves 19F and 31P NMR in HSO3F and SO2 solution including spectral simulation by the WIN-DAISY method and FT-IR and Raman spectra. Spectroscopic evidence suggests that the metal–ligand bond involves predominantly σ-bonding with drastically reduced π-back-donation. Key words: gold(I) complex, linear; gold(I) PF3 complex; 31P NMR; 19F NMR; vibrational spectra.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The design and construction of a catalytic reactor (AgF2 on copper turnings as support) for the fluorination of SO3 in a flow reaction to produce bis (fluorosulfuryl) peroxide (S2O6F2) are described in detail. An operating procedure is developed that allows the production of S2O6F2 in substantial quantities (802-120 g h−1) and avoids the accidental production of fluorine fluorosulfate (FOSO2F) as a hazardous byproduct. Also described are purification methods and disposal procedures for highly reactive byproducts (F2 or FOSO2F) in a safe and environmentally friendly manner, as well as the long-term storage of S2O6F2.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

In order to correlate Sn-119 Mossbauer parameters and structural data for dimethyltin(IV) derivatives, the molecular structures of bis(acetato)dimethyltin(IV) and bis(trifluoroace tato)dimethyltin(IV) were determined by single crystal X-ray diffration. Crystals of Me(2)Sn(OOCCH3)(2) are monoclinic, a = 26.282(4), b = 5.282(1), c = 14.434(3) Angstrom, beta = 101.17(2)degrees, Z = 8, space group C2/c, and those of [Me(2)Sn(OOCCF3)(2)](n) are monoclinic, a = 8.444(1), b = 17.689(1), c = 15.368(1) Angstrom, beta = 93.013(9)degrees, Z = 8, space group Cc. The structures were solved by the Patterson method and were refined by full-matrix least-squares procedures to R = 0.025 and 0.027 (R(w) = 0.023 and 0.030) for 2298 and 4182 reflections with I greater than or equal to 3 sigma(F-2), respectively.

The syntheses of the binary fluorosulfates, Zr(SO3F)4 and Hf(SO3F)4, by oxidation of the corresponding metalpowders with bis(fluorosulfuryl) peroxide, S2O6F2, in fluorosulfuric acid, HSO3F, are described. The resulting products are white hygroscopic solids which are not sufficiently soluble in HSO3F to allow electrical conductivity and NMR studies or Hammett acidity function (H0) determinations in order to evaluate their use as Lewis acids in conjugate superacid systems. Oxidation of titanium under similar conditions resulted in the formation of a greenish-yellow resin-like material of limited thermal stability with the approximate composition Ti(SO3F)4. However, infrared spectra indicated the presence of small amounts of HSO3F. In addition, the solvolysis of ZrCl4 in an excess of HSO3F at 25 °C has been investigated as a potential route to Zr(SO3F)4. The results indicate that short reaction times of 1–2 d yielded incompletely substituted products of the approximate composition ZrClx,(SO3F)4−x (x = 0.22), while prolonged reaction times of 3–4 weeks gave rise to partially decomposed materials of approximate composition ZrO0.5F1.5(SO3F)1.5. The ability of all three tetrakis(fluorosulfato) metallates to act as SO3F− ion acceptors is evident from the isolation of thermally stable salts of the composition Cs2[M(SO3F)6] (M=Ti, Zr or Hf) when the metal oxidation was carried out in the presence of 2 mol equiv. of CsSO3F. All the materials were characterized by their vibrational spectra, which are extremely similar and closely resemble those of previously reported cesium hexakis(fluorosulfato) metallates.

The radical intermediates formed initially in the reaction of S2O6F2 with S4N4 and S8 have been studied by ESR spectroscopy at X-band level. The transient radical formed in the reaction between S2O6F2 and S4N4 has the spin Hamiltonian parameters gxx=2.0014, gyy=2.0054, gzz=2.0249, Axx=22.5 MHz, Ayy=4.5 MHz, Azz=2.0 MHz and Qzz=4 MHz as determined by simulation of ESR lineshapes obtained from polycrystalline samples. The spin Hamiltonian parameters are very similar to those previously reported for [S3N2]+·, and the spectra are interpreted as being most likely due to the [S3N2]+· radical. The reaction between S2O6F2 and S8 under similar conditions produces a radical that has a g-tensor of the form gxx=2.0026, gyy=2.0184, gzz=2.0258, as determined by simulation. The transient species generated is postulated to be a similar S5+· radical.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The reactions of fluorine-fluorosulfate, FOSO2F, with SSF2, SeF4, AsF3 and MoF5 have been studied, and its previously reported reactions with SF4, Br2 and I2 re-investigated in order to test its suitability as a synthetic reagent. All substrates reacted exothermically, and sometimes explosively, between 80-298 K. The presence of the byproducts obtained may be rationalized by the thermal decomposition of some of the FOSO2F, which proceeds along two pathways, i.e. FOSO2F --> 1/2O2 + SO2F2 and FOSO2F --> 1/2F2 + 1/2S2O6F2, during the extremely exothermic reactions via radical intermediates. The fluorine formed gives rise to fully fluorinated products, and the SO3F. radicals, initially formed, either dimerize to give S2O6F2 or decompose to O2 and S2O5F2. Element fluoride-fluorosulfates, when formed at all, were obtained in low yields only when SO2F2 or SO2FCl were used as suitable moderators. The complete vibrational spectra of EF5OSO2F (E = S, Se or Te) have been studied and assigned. The reactions of I2, Br2 and AsF3 with FOSO2F yielded viscous liquids of the approximate, non-stoichiometric composition EFn(SO5F)5-n (E = As or I) and EFn(SO3F)3-n (E = Br), with n = non-integral number. All compounds were characterized by their vibrational and F-19 NMR spectra, and in the case of SeF5OSO2F by Se-77 NMR methods.

The synthesis of the bis(carbonyl)gold(I) salt, [Au(CO)2] [Sb2F11], is achieved in a two-step procedure: the reduction of gold(III) fluorosulfate, Au(SO3F)3, in HSO3F to give AU(CO)SO3F as an intermediate, followed by solvolysis in liquid antimony(V) fluoride in the presence of carbon monoxide. The use of (CO)-C-13 or (CO)-O-18 permits the synthesis of the corresponding isotopically labeled salts. The compound is thermally stable up to 130-degrees-C. The cation has D(infinity h) symmetry, and all seven fundamentals, three Raman and four IR active modes, are observed. A normal coordinate analysis (NCA) and general valence force-field (GVFF) calculations are carried out and allow comparison to the isoelectronic and isosteric molecular species Hg(CN)2 and [Au(CN)2]-. The near absence of gold to carbon pi-back donation in [Au(CO)2]+ is manifested in strong carbon-oxygen bonds and consequently rather weak gold-carbon bonds, reflected in the highest CO-stretching frequencies so far observed for a metal carbonyl derivative with 2254 (nu1) and 2217 (nu3) cm-1 and a stretching force constant of 20.1 X 10(2) Nm-1. In the C-13 NMR spectrum a single-line resonance at 174 ppm is attributed to ([Au(CO)2]+)-C-13, while the ([Au(CO)]+)-C-13 chemical shift changes from 162 ppm in HSO3F to 158 ppm in magic acid (HSO3F/SbF5). The resonances for ([Au(CO)2]+)-C-13 and ([Au(CO)]+)-C-13 in the same solution are found to undergo coalescence at elevated temperature indicative of slow CO exchange. The coalescence temperature is solvent dependent, 325 K in HSO3F and 395 K in the more dilute HSO3F/SbF5 mixture. Attempts to recrystallize [Au(CO)2] [Sb2F11] from acetonitrile result in the formation of single crystals of [Au(NCCH3)2][SbF6] instead. The compound crystallizes in a cubic unit cell, space group Pa3BAR, with a = 10.250 (2) angstrom and Z = 4. The structure was determined by Patterson and Fourier methods and refined by least-squares techniques to R = 0.023 and R(w) = 0.024 for 147 reflections with I > 3sigma(I). The crystal contains linear [Au(NCCH3)2]+ cations and octahedral [SbF6]- anions, with normal dimensions.

The partial pyrolysis of gold(III) fluorosulfate, Au(SO3F)3, at temperatures below 145-degrees-C allows the generation of Au2+ defects in the solid residue by reductive elimination of SO3F. radicals. Solvated Au2+ is obtained by the reduction of Au(SO3F)3 in HSO3F solution by gold powder at 65-degrees-C. Both systems are studied by ESR and identical high g(iso) values of g = 2.360 are found. Hyperfine splitting due to Au-197, I = 3/2, is observed in frozen solutions of Au2+(solv). Pyrolysis of Br3[Au(SO3F)4] also gives partly pyrolyzed Au(SO3F)3, with a sufficiently high Au2+ ion concentration, to allow a magnetic susceptibility study between 100 and 295 K.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Fluorine fluorosulfate, FOSO2F, appears to be ideally suited to introduce both fluorine and fluorosulfate into a molecule and a number of such oxidative addition reactions have been reported early on1). Once the highly explosive nature of FOSO2F was recognized2), almost all synthetic work stopped. A number of these addition reactions with the fluorides S2F2, SF4, SeF4, AsF3, SbF3 and MoF5 and the halogen Br2 and I2 have been re-investigated or studied for the first time. The following conclusions are reached: (i) All reactions of FOSO2F are vigorous and often explosive with FOSO2F acting primarily as fluorinating agent. (ii) Byproducts observed include always bis(fluorosulfuryl) peroxide, S2O6F2, and sometimes SO2F2 and O2. (iii) Except for additions to SF4 and SeF4 where SF5SO3F and SeF5SO3F form in low yield, and are studied by heteronuclear NMR and vibrational spectroscopy, the reaction products are frequently non-stoichiomenric eg. IFn(SO3F)5−n, or BrF(SO3F)3−nwith n noninteger numbers. (iv) In most instances safe alternative routes are explored to avoid the use of FOSO2F.