Facile hydrometalation of alkynes by nido-1,2-(CpRuH)(2)B(3)H(7) yielding novel Ru-B edge-bridging alkylidenes. Stepwise conversion of HCtbd1;CC(O)OMe into nido-1,2-(CpRuH)(2)-3-HOB-4-MeC-5-MeOC-BH(3), Cp = eta(5)-C(5)Me(5)

The reaction of the alkyne HCCC(O)OMe with 7 sep 1,2-(Cp*RuH)2B3H7 leads to hydroboration plus hydroruthenation to produce nido-1,3-mu-Me{C(O)OMe}C-1,2-(Cp*Ru)2B3H7, a compound with an exocluster ruthenium-boron mu-alkylidene that exists in two isomeric forms. Both isomers undergo rearrangement with intramolecular chelation of the carbonyl oxygen at a boron site, thereby opening the cluster and generating arachno-2,3,-mu(C)-5-eta1(O)-Me{C(O)OMe}C-1,2-(Cp*Ru)2B3H7. Further heating leads to deoxygenation of the carbonyl fragment by a boron center concurrent with insertion of the carbon atom into the metallaborane cage to give nido-1,2-(Cp*RuH)2-3-HOB-4-MeC-5-MeOC-BH3.     

Determination of oxytetracycline in urine and human serum by differential pulse polarography

Summary A differential pulse polarographic method for the determination of oxytetracycline in urine and human serum in acid media (HClO₄ of pH 2) is proposed. The effects of the amount of sample taken and the concentration of HClO₄ present were investigated. The detection limit was 5.5×10^–6 mol/l. The standard deviation of the determination of 5.5×10^–5 mol/l of oxytetracycline in 2 ml of urine was 1.7×10^–6 mol/l and that of the determination of 5.5×10^–5 mol/l of oxytetracycline in 2 ml of human serum was 1.9×10^–6 mol/l.

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Bestimmung von Oxytetracyclin in Urin und Humanserum durch Differential-Pulspolarography

     

The reaction of aromatic α,β-unsaturated ketones with 4,5-diamino-1,6-dihydropyrimidin-6-ones

The reaction of 4,5-diamino-1,6-dihydropyrimidin-6-ones 1 with one equivalent of the chalcones 2 leads in an acidic medium to the formation of the 2,4-diaryl-2,3,6,7-tetrahydro-1H-pyrimido[4,5-b][1,4]diazepin-6-ones 3a-m . The structure elucidation of the products is based on detailed nmr investigations including selective ¹³C[¹H] decoupling experiments.     

An efficient synthesis of 6-fluoronalidixic acid and its conversion to enoxacin

1-Ethyl-6-fluoro-1,4-dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carboxylic acid ( 8 ) has been prepared in large quantities by a highly efficient process. It has in turn been degraded to give 7-chloro-1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid ( 11 ). This intermediate has been reacted with piperazine to give the known antibacterial agent, enoxacin ( 12 ).     

不对称Fe-Fe双金属化合物[Cp*Fe(dppe)(C≡CFc))[PF6]n(n=0，1)的合成、结构及光谱性质的研究(英)

A biased bimetallic Fe-Fe complex Cp^*Fe(dppe)(C≡CFc) (1) was synthesized from FcC≡CH (Fc=C₅H₄FeC₅H₅) and Cp^*Fe(dppe)Cl (Cp^*=C₅Me₅). Its one-electron oxidation species [Cp^*Fe(dppe)(C≡CFc)][PF₆] (1a) was also prepared and the spectroscopic properties of 1a was studied. The single-crystal X-ray diffraction analysis of 1 shows that ferrocenylacetylene is bonded at the terminal carbon to the iron center in the Cp^*Fe(dppe) part. Crystallographic data for 1: monoclinic, space group C2/c, with a=4.067 65(14) nm, b=1.260 74(4) nm, c=1.649 89(5) nm, β=104.387(10)°, V=8.195 7(5) nm³, Z=8, D_c=1.354 g·cm^-3, F(000)=3512, μ=0.822 mm^-1. The structure was refined to R₁=0.038 4, wR₂=0.100 0. CCDC: 234893.     

High-spin to low-spin relaxation kinetics in the [Fe(TRIM)2]Cl2 complex

A quasi-quantitative photo-induced low-spin (LS)-->high-spin (HS) conversion of FeII ions has been observed in the [Fe(TRIM)2]Cl2 complex by irradiating the sample with blue light (488 nm) at 10 K. The time dependence of the HS-->LS relaxation has been studied between 10 K and 44 K by means of magnetic susceptibility measurements. These relaxation curves could be satisfactorily fitted by mono-exponential decays including tunnelling effect except for temperatures below 30 K. The introduction of a distribution of vibrational frequencies into this model improved significantly the fits in the low-temperature range and gave a good agreement with the experimental data in the whole temperature range suggesting a multi-rate relaxation process in this complex.     

Determination of promethazine hydrochloride with bromophenol blue by a turbidimetric method and flow injection analysis

A flow injection analysis procedure for the turbidimetric determination of promethazine is proposed. The sample solution is injected directly into the carrier reagent stream, which is composed of 1.16 × 10⁻³M bromophenol blue at pH 1.20. The calibration graph is linear over the range 25–197 ppm of promethazine. The influence of some foreign substances was also investigated. The method is applied to promethazine determination in a pharmaceutical formulation.     

Crystal engineering: Supramolecular structures by cocrystallization ofMeso-1,2-diphenyl-1,2-ethanediol and bisimines,simple cases of molecular recognition

The crystal structures of molecular complexes betweenmeso- 1,2-diphenyl-1,2-ethanediol and two bisimines (N,N-(dibenzylidene)-ethylenediamine and glyoxylidene-bis(2,4-dimethyl-3-pentyl-amine) are reported at different temperatures. The structure-determining motif of the cocrystalline arrangement is one single O-H . N hydrogen bond resulting in infinite ladderlike polymers. The supramolecular structure is formed by recognition of fitting species: Thed- orl-isomers do not arrange in such structures.¹H NMR experiments show that no prearrangements take place by forming complexes in solution.