Synthesis of Bis(pentafluoroethyl)germanes

The chemistry of bis(pentafluoroethyl)germanes (C₂F₅)₂GeX₂ is presented. The synthesis of such species requires Br₂GePh₂, wherein the phenyl substituents function as suitable protecting groups. After treatment with two equivalents of LiC₂F₅, (C₂F₅)₂GePh₂ is produced. The replacement of the phenyl rings is smoothly effected by gaseous HBr or HCl in the presence of a Lewis acidic catalyst. The trigermoxane [(C₂F₅)₂GeO]₃ results from the reaction of (C₂F₅)₂GeBr₂ with Ag₂CO₃. Its crystalline 1,10‐phenanthroline adduct was fully characterised by X‐ray diffraction. The combination of (C₂F₅)₂GeBr₂ with Bu₃SnH gave rise to the formation of (C₂F₅)₂GeH₂.     

Design and characterization of a high temperature fiber-optic pressure transducer

We have measured the pressure response of a high temperature pressure transducer fabricated from a super alloy. This transducer contains a microbend fiber-optic sensor to measure diaphragm deflection and a reference fiber to help reduce light source fluctuations caused by perturbations in the fiber leads. The transducer was characterized at pressures up to 22.8 MPa and temperatures to 430°C. The experimental data taken at constant temperature shows a 0.58 percent (of full scale pressure) minimum deviation between the fiber-optic pressure transducer output and output of a calibrated gage pressure transducer. Over the entire temperature range of20-430degC, the fiber-optic pressure transducer output exhibits a 1.2-percent (of full scale pressure) maximum deviation from calibrated pressure.     

F- and D-decays

The rates of some important weak decay modes of F- and D-mesons are estimated. A simple decay mechanism for non-leptonic two-body decays is suggested. The measurements of the corresponding decay ratios give sensitive tests for the form of the effective Hamiltonian. F-decays to ø and η channels are expected to dominate over direct decays to pairs of strange particles.     

Coordination Chemistry of the Carboxylate Type Siderophore Rhizoferrin: The Iron(III) Complex and Its Metal Analogs

Rhizoferrin is a member of a new class of siderophores (microbial iron transport compounds) based on carboxylate and hydroxy donor groups rather than the commonly encountered hydroxamates and catecholates. We have studied the coordination chemistry of rhizoferrin (Rf), as a representative of this group, with Fe(3+), Rh(3+), Cr(3+), Al(3+), Ga(3+), VO(2+), and Cu(2+). The metal complexes have been studied by UV-vis, CD, NMR, and EPR spectroscopies and mass spectrometry. The formation constants for the iron complex have also been measured and yield a log K(LFe) of 25.3. The Rh and Cr rhizoferrin complexes are unusual in that they appear to adopt a chirality about the metal center that is the opposite of the native iron analog. Several of the alternative metal ion complexes are found to have biological activity toward Morganella morganii in a plate type assay.     

On optimal third order rotatable designs

We obtain results for choosing optimal third order rotatable designs for the fitting of a third order polynomial response surface model, for m3 factors. By representing the surface in terms of Kronecker algebra, it can be established that the two parameter family of boundary nucleus designs forms a complete class, under the Loewner matrix ordering. In this paper, we first narrow the class further to a smaller complete class, under the componentwise eigenvalue ordering. We then calculate specific optimal designs under Kiefer's % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqOXdy2aaS% baaSqaaiaadchaaeqaaaaa!38C6!\[\phi _p \] (which include the often used E-, A-, and D-criteria). The E-optimal design attains a particularly simple, explicit form.N. R. D. is grateful for the partial support from the Scientific and Environmental Affairs Division of the North Atlantic Treaty Organization, and from the National Security Agency through Grant MDA904-95-H-1020.     

Ferrocenyl Sulfinylimide and Diferrocenyl Sulfurdiimide,Fc?NSO and Fc(NSN)Fc

1 Abbreviations and Nomenclature: Fc = η¹-ferrocenyl, CpFe(C₅H₄-); Cp = η⁵-cyclopentadienyl, η⁵-C₅H₅. Compounds containing the —NSO group are designated as either thionylimides, sulfinylimides or N-sulfinylamines. The systematic name is imido oxo sulfuranes(IV).

The reactions of ferrocenylamine, Fc? NH₂ ( 1 ), with thionyl chloride and sulfur dichloride in hexane solution in the presence of triethylamine lead to the title compounds Fc? NSO ( 2 ) and Fc(NSN)Fc ( 3 ), respectively, 2 and 3 have also been obtained in reactions of the silylated ferrocenylamine, Fc? NH(SiMe₃) ( 1b ), with thionyl chloride. The ferrocenyl sulfinylimide 2 has been converted to sulfurdiimides such as Fc(NSN)Fc ( 3 ) and Fc(NSN)R (R = ^tBu ( 4a ), SiMe₃ ( 4b )) by reaction with the lithium derivative of silylated amines, LiN(SiMe₃)R (R = Fc, ^tBu, SiMe₃). The new ferrocenyl compounds 2–4 have been characterized by their NMR spectra, and their electrochemical behaviour has been studied. The molecular structure of Fc? NSO ( 2 ) has been determined by an X-ray structure analysis; the sulfinylimide has the Z configuration, and the —NSO group is coplanar with the cyclopentadienyl ring to which it is attached.