Phosphaalkynes and phosphaalkenes

Anellated heterophospholes and phospholides and analogies with related non-phosphorus systems.

Publisher Summary Two rules have proved particularly useful with respect to attempts to classify and systemize the variety of elements and their compounds—(1) the octet rule and (2) the double-bond rule. The double-bond rule denies the possibility of stable pπ – pπ double bonds among elements beyond the second period. Thus, carbon dioxide is a volatile molecule in which the electronic stabilization of the carbon with the oxygens is reached via two π bonds. The double-bond rule requirement that has proved correct with numerous natural as well as synthesized compounds, with respect to modern conceptions, is because of enlarged and diffused p orbitals of the heavier elements that do not allow sufficient overlap for the stabilization of covalent π bond. Because of this interpretation it is easily neglected that the periodic system of the elements is related to natural law; the strict interpretation of the two doctrines, which are only rules, may hinder the discovery of new classes of compounds.

Double Bonds Between Phosphorus and Carbon

Niederkoordinierte Phosphorverbindungen zahlen angesichts der grosen Zahl stabiler Verbindungen langst nicht mehr zu den „Exoten” unter den Hauptgruppenelement-Verbindungen. Neben P-C-Mehrfachbindungssystemen, deren Chemie durch die enge Verwandtschaft mit organischen Verbindungen gepragt wird, gilt das Interesse vor allem P-N-Mehrfachbindungssystemen (Iminophosphanen). Diese Verbindungsklasse zeichnet sich durch eine ungewohnliche Strukturvielfalt und ein variationsreiches chemisches Verhalten aus, so das Iminophosphane zu wertvollen Synthesebausteinen in der Organoelementchemie wurden.

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Iminophosphane — unkonventionelle Hauptgruppenelement‐Verbindungen

It is always instructive to recall the great names of chemistry and their contributions. This is particularly so in organophosphorus chemistry for within a dozen names one can review a century of endeavour in this field.

Organophosphorus Chemistry Today

In the course of the last 20 years the λ3σ2- and λ3σ2As-Chemistry has progressed rapidly Compounds, containing λ3P- and σ3As-(p-p)π-bonds, considered before to be unstable have become the basis of a new and extremely interesting branch of chemistry Cycloadditions to the P˭C and As˭C-bonds are developing rapidly at the present time Many new types of compounds have been obtained and many rearrangements have been discovered, which are presented and discussed in this compilation Die Chemie der λ3σ2-Phosphor und λ3σ2-Arsen-Verbindungen befindet sich seit etwa 20 Jahren in sturmischer Entwicklung Verbindungen dieser Elemente mit pπ-pπ-Mehrfachbindungen, die fruher als unbestandig galten, konnen isoliert und untersucht werden Zur Zeit stehen Cycloadditionen an die Mehrfachbindungen im Vordergrund des Interesses Neue Verbindungstypen wurden erhalten und zahlreiche Umlagerungen und Folgereaktionen beobachtet, deren Besonderheiten in der vorliegenden ubersicht behandelt werden

B. A. Arbuzov

Papers

Cycloaddition an Verbindungen mit λ3σ2-Phosphor- und λ3σ2-Arsen-Mehrfachbindungen