摘要:

AbstractBond fission of molecular sulfur, selenium, and tellurium by lithiotriphenylmetal compounds (of Ge, Sn, Pb) is summarized. The products are suitable as starting materials for synthesis of new “ether analogues”. Transphenylation with tetraphenylstannane is interpreted as a high‐temperature variant of the usual fission of chalcogen molecules by nucleophilic reagents. In principle, transphenylation can be applied also to other elements, as is illustrated for phosphorus. In the syntheses achieved, many of the tin‐phosphorus compounds arising as intermediates can be i

ISSN:0570-0833    

DOI:10.1002/anie.196510071

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

摘要:

AbstractThe preparations, properties, structures, and chemical reactions of silicon‐sulfur compounds are reported. The chain structure of the polymeric silicon disulfide is used as a basis from which the various classes of compounds can be derived: cyclothiasilanes, disilyl sulfides, silanethiols, and organothiosilanes. Infrared data and force constants of the Si‐S bond are discus

ISSN:0570-0833    

DOI:10.1002/anie.196510141

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

摘要:

AbstractThe preparation of heterocycles containing phosphorus is described. The chemical behavior of ring systems containing trivalent phosphorus is mainly determined by their phosphine character; heterocyclic behavior in the ordinary sense is shown by rings containing functional groups. Syntheses and reactions of cyclic compounds of pentavalent and hexavalent phosphorus are particularly interesting.

ISSN:0570-0833    

DOI:10.1002/anie.196510231

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

摘要:

AbstractThe present paper is concerned mainly with studies on the electronic structure of nonalternant hydrocarbons by quantum‐chemical methods. The references to original publications are by no means exhaustive, but an attempt has been made to cover the entire field. (Analogues and derivatives of non‐alternant hydrocarbons are only touched.) The intention is to outline the present situation with regard to quantum‐mechanical studies on non‐alternant hydrocarbons, and to indicate to the chemist the use of the theoretical characteristics obtained by various approximations of the MOLCAO method.The simplest modification of the MO–LCAO method is the Hückel approximation (HMO), in which the molecular orbitals ψi are expressed as linear combinations of the atomic orbitals ϕj; in the π‐electron approximation only the 2pzatomic orbitals are considered. For the interaction of n orbitals we have:(a)\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$$\psi_{\rm i} = \sum_{{\rm j}\,=\,1}^{\rm n} {\rm c}_{\rm ij}\varphi_{\rm j}$$\end{document}The π electron densities and the bond ordes can be calculated from the coefficients cij of the molecular orbitals. The energies Ei of the molecular orbitals are found by solving the determinantal equation' the n permitted levels are given by:(b)\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$${\rm E}_{\rm i} = \alpha + {\rm k}_{\rm i}\beta,$$\end{document}where α is the Columb integral of the 2Pzorbital of carbon and β is the resonance intergral of the CC π‐bond (and also the unit of energy in the HMO theory). The occupied molecular orbital with the highest energy is denoted by k1 (normal state), and the unoccupied level with the lowest energy by k−1(valence state). The transfer of an electron from k1 to k−1is called N → V1 excitation.The main difference between the HMO method and the more accurate MOLCAO methods is that electronic interactions are explicitly taken into account in the latter; these methods arePople'sSCF (self‐consistent field) method andPariserandParr'sLCI (limite

ISSN:0570-0833    

DOI:10.1002/anie.196510391

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

摘要:

AbstractThe physical properties of copolymers are determined by their compostions and by the distribution of monomeric sequences in their chains. In some cases, sequence distributions can be determined from or correlated with physical properties observed for copolymers. Such determinations or correlations are relatively simple when calculations are based on run numbers.

ISSN:0570-0833    

DOI:10.1002/anie.196510511

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

摘要:

AbstractAfter it had become known that three types of condensed inorganic phosphates, i.e. metaphosphates, polyphosphates, and ultraphosphates, exist, attempts were made to elucidate their formation, properties, and mutual relationships. Metaphosphates and polyphosphates containing up to eight or ten monomer units can be separated chromatographically. In the melts, equilibria exist between the various types of phosphate anions. Annealing of the glasses leads to crystalline products, sometimes containing only one type of anion. The glass‐crystal transition proceeds via monomeric XO −3anions. This has been shown in the case of polyarsenatophosphates, in which the As atoms are randomly distributed over the chains in the vitreous state, but are located at preferred positions in the crystalline state. The maximum degree of dissociation of polyphosphates and polyphosphoric acids in water is 30%, which accounts for the ion exchange and the chelating effects. The cation‐catalysed decomposition of polyphosphates can take place either by hydrolytic degradation from the chain ends, or by rearrangement within the chains to form metapho

ISSN:0570-0833    

DOI:10.1002/anie.196510611

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196510723

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196510731

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196510742

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.196510752

出版商:Hüthig&Wepf Verlag    

年代:1965

数据来源: WILEY