Synthesis of trans-azoalkane ligands RNNR by dehalogenation of N,N-dihaloalkylamines,RNCl2

N,N-Dihaloalkylamines, RNCl₂, are dehalogenated by organometallic sodium or lithium salts to give trans-azoalkanes, RNNR, and their corresponding metal complexes.     

1,2-Dipyridazinyl-äthen- und-äthan-1,2-diole aus Pyridazin-carbaldehyden

Treatment of pyridazine-4-carboxaldehyde with catalytic amounts of KCN results in formation of pyridazine-4-carboxylic acid and two stereoisomeric diols (4,5). The configurations of4 and5 are explained on basis of the¹H-NMR-spectra, the mechanism of reaction is discussed. Pyridazine-3-carboxaldehyde (10) reacts with HCN to form the addition product of10-cyanhydrine to10 (11). HCN-elimination from11 yields the enediol12 which by oxygen is oxidized to pyridazine-3-carboxylic acid or its methyl ester.

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Herrn Univ.-Prof. Dr.M. Pailer mit den besten Wünschen zum 65. Geburtstag gewidmet.

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5. Mitt.:G. Heinisch, E. Luszczak undM. Pailer, Mh. Chem.105, 763 (1974).     

The effect of molecular topology on π-molecular-orbital energies

Three models for constructing topologically related pairs of molecular isomers are discussed at length. The topological-effect-on-molecular-orbitals (TEMO) theorem is presented in detail and illustrated with experimental data; this theorem demonstrates that molecular topology imposes constraints in the form of general interlacing rules on the MO energy patterns of topologically related molecules. Further, non-empirical SCF MO calculations have been performed for topologically related o- and p-divinylbenzenes, difluorobenzenes, benzoquinones, and benzoquinodimethanes in standard and optimized geometries using various basis sets. In most cases, the SCF -MO eigenvalue patterns of topological related isomers are in complete agreement with the TEMO theorem, thus demonstrating the dominant influence of topology on the -MO energies. A modified version of the generalized perturbationalvariational Rayleigh-Ritz (PV-RR) procedure is described which is used to study the occasional observed deviations from the TEMO predictions; this procedure had been combined with the concept of critical (i.e. the threshold value of the perturbation parameter at which the TEMO order of a pair of MO eigenvalues starts to invert), thus enabling us to analyze in quantitative detail the physical factors which compete with molecular topology in conditioning the ab initio MO energy patterns.Part 10 of the TEMO series; for Part 9, see Ref. [9b].Dedicated to Prof. Dr. Günther Wilke on the occasion of his 60th birthday     

Convexity and finite quantum logics

The notion of a superposition of a set of states and that of a Jauch-Piron state are geometrically interpreted in the context of the facial structure of the state space of a finite quantum logic.