摘要:

AbstractThe electronic spectra of 1,3‐cyclohexadiene,(Z)‐ and(E)‐1,3,5‐hexatriene were measured and interpreted.The absorptions between 220 and 280 nm in the gas phase are π → πx‐transitions whereas the second absorption (180‐210 nm) in these compounds is considered to be a Rydberg transition. A weak π → πx‐transition is hidden by the latter absorption in(Z)‐hexatriene. The band in the solution spectrum of cyclohexadiene at 190 nm is thought to correspond to the band at 175 nm in gaseous cyclohexadiene.Triplet absorption spectra were measured in heavy atom solvents (CH2I2, CHBr3).A scheme of

ISSN:0165-0513    

DOI:10.1002/recl.19730921102

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractIrradiation ofdl‐mandelic, phenylacetic, formic, malonic ordl‐tartaric acid in aqueous or ethanolic solutions with U. V. light results in the photodecomposition of these acids into ·COOH and the respective residual radicals. The ·COOH radical has strong reducing properties and can reduce azo dyes, if they are added to the solution prior to irradiation, to amines. The residual radicals formed together with ·COOH upon photodecomposition of the carboxylic acids, can cause fading of the dyes either by reduction or by addition to the chromophoric

ISSN:0165-0513    

DOI:10.1002/recl.19730921103

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe preparation and properties of M(Bu2dtc)2X2(M = Pd, Pt and X = Br, I) are reported. From the platinum complexes two isomers were isolated. The crystal structure of thecis‐isomer of Pt(Bu2dtc)2I2is determined by a threedimensional X‐ray analysis. The orthorhombic cell, space group Fddd, witha= 33.37(3),b= 34.16(3),c= 20.19(2) Å and V = 23010(40) Å3contains 32 formula units. Atomic parameters were refined to a conventional R value of 0.073 for 1417 independent non‐zero reflections. The platinum atom is distorted octahedrally coordinated by two iodine and four sulfur atoms with average distances of Pt ‐ I = 2.66 and Pt ‐ S = 2.35 Å. The intra‐ and one of the intermolecular I‐I distances (resp. 3.79 and 3.37 Å) are short compared with an I‐I Van der Waals contact.ESCA spectra show the other isomer to be a Pt(IV) complex too. NMR data suggest atrans‐structurefor this isomer.With Bu4tds these complexes yield M(Bu2dtc)3X (M = Pt, Pd and X = Br, I) of which some

ISSN:0165-0513    

DOI:10.1002/recl.19730921104

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe octadecapeptide amide I and the tetracosapeptide II containing homoarginine in position 8 have been synthesized according to a generally approved scheme. As a new feature, the hydroxyl functions of the serine and tyrosine residues were protected in the synthesis of theN‐terminal decapeptide. The latter, presumably by its higher solubility in organic solvents, afforded the protected end products in an improved yield. For complete deprotection, however, acid‐treatment of these compounds had to be extended over longer periods than in the absence of the ether functi

ISSN:0165-0513    

DOI:10.1002/recl.19730921105

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractIn the presence of catalytic amounts of [Rh(CO)2Cl]2the monomethylene adduct of hexamethylbicyclo[2.2.0]hexa‐2,5‐diene (1) can be quantitatively converted into hexamethylbenzene and a monomethylene carbenoid species; the latter can be trapped by cyclohexene. The hexamethylbenzene is presumably formed via (a) catalysed electrocyclic opening of the cyclobutene ring in coordinated 1 to give coordinated hexamethylnorcaradiene, and (b) extrusion of the carbenoid species. The proposed reaction pathway is supported by the fact that penta‐ and hexamethylcycloheptatriene are also subject to the extrusion reaction in the presence of the catalyst. Under the same catalytic conditions 1,6‐dimethyl‐oxepine is quantitively converted intoo‐xylene.Apart from the aromatization the catalyst effects double‐bond isomerization of the methyl‐substituted cy

ISSN:0165-0513    

DOI:10.1002/recl.19730921106

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19730921107

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19730921108

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe structure of the octahedral N6‐coordinated potassium tris(biuretato)‐cobaltate(III) hydrate, K3Co(HNCONHCONH)3. xH2O (x = 6.38) was determined by X‐ray analysis. The crystals are triclinic, space group\documentclass{article}\pagestyle{empty}\begin{document}$ \bar 1 $\end{document}, with unit cell dimensions a = 9.296, b = 11.168,c= 11.631 Å, α = 93.76°, β = 112.71°, γ = 74.57° and two formula units per cell. 3275 non‐zero reflections were measured with an automatic diffractometer. The structure was refined by full matrix least‐squares methods to a conventional R‐value of 0.05. The cobalt is in nearly regular octahedral coordination with an average Co‐N distance of 1.916 Å. The slightly puckered biuretato ligands are somewhat bent out of the plane formed by four coordinating nitro

ISSN:0165-0513    

DOI:10.1002/recl.19730921109

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractMagnetic susceptibility measurements in the temperature range of 4 to 150°K have been performed on samples of CoxMg1‐xO, x ranging from 2.5% to 5% and on LiMg1‐xCoxPo4, x ranging from 1.5% to 5%. Deviations from the single ion susceptibility have been observed for all samples and explained by taking into account an effective exchange interaction 2JsTi. STjbetween ions within various types of isolated clusters, s being the fictitious spin of the doublet ground state.From the experimental data on CoxMg1‐xO forJ(90°)/k andJ(180°)/k the values 5.0 °± 0.3°K and 135 ± 10°K have been derived, while in LiMg1‐xCoxPO4J(132°)/k has been found e

ISSN:0165-0513    

DOI:10.1002/recl.19730921110

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe conjugate addition of methyl Grignard reagents to 5α‐1‐estren‐3‐ones leads to 1α‐methyl derivatives. It is suspected that this is due to formation of a half chair conformation of ring A upon 1α attack, whereas 1β‐attack would yield a product having a half boat conform

ISSN:0165-0513    

DOI:10.1002/recl.19730921111

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY