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/pdf/metal-assisted-cycloaddition-reactions-in-organotransition-2cf6yzr4gb.pdf

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

http://pubs.acs.org/doi/pdf/10.1021/om900088z

The Grignard Reagents

Alkyl, Hydride, and Hydroxide Derivatives of the s- and p-Block Elements Supported by Poly(Pyrazolyl)Borato Ligation: Models for Carbonic Anhydrase, Receptors for Anions, and the Study of Controlled Crystallographic Disorder

Die Erforschung der Reaktivitat und Struktur alkalimetallorganischer Verbindungen hat in den letzten Jahrzehnten eine geradezu sturmische Entwicklung durchlaufen. Zu diesen Verbindungen gehoren einige fur das Verstandnis der chemischen Bindung besonders wichtige und auch einfache wie die Methylverbindungen der Alkalimetalle, deren Strukturen nun vollstandig aufgeklart sind. Ganz allgemein erwiesen sich die organischen Verbindungen der Alkalimetalle und auch des Magnesiums als Ionenaggregate, deren Eigenschaften sich durch Solvatisierung, z.B. durch Ether und Amine, stark verandern lassen. Auf diesen Erkenntnissen beruhen auch wichtige Fortschritte bei der Synthese vor allem von Verbindungen der schwereren Alkalimetalle. Lange galten die Alkalimetalle als wenig koordinationsfreundlich, und ihre Komplexchemie bot kaum Uberraschungen. Dieses Bild hat sich vollig gewandelt. Kristallstrukturuntersuchungen erbrachten eine Fulle von oft uberraschenden Strukturtypen (Ringe, Heterocubane, Ketten, Stapel etc.), nicht nur bei ihren organischen Verbindungen, sondern auch bei ihren Amiden, Imiden, Alkoxiden, Phenoxiden, Enolaten und sogar Halogeniden. Ein Vergleich last interessante Gemeinsamkeiten der scheinbar so verschiedenen Verbindungen erkennen und fuhrt zu einer allgemeineren Klassifizierung derartiger Strukturtypen mit C-, N-, O- und Halogeno-Liganden.

Strukturen alkalimetallorganischer und verwandter Verbindungen

Great advances have been made in the past decade in the field of NMR spectroscopy. Apart from the development of completely new areas of application, such as in solid-state chemistry, in materials science, in physiological chemistry, and in medicine, with the introduction of new pulse spectroscopic methods and the application of high magnetic field strengths important progress has also been made in the traditional field of high-resolution NMR spectroscopy. Thus, among other things, the observation of metal resonances has been facilitated and new areas of application have been opened up in inorganic and organometallic chemistry. In this review, recent detection methods for spin-1/2 and quadrupolar metal nuclei are presented and discussed. The use of metal-NMR spectroscopy with respect to problems of a typical chemical nature, mainly from the field of organometallics, is demonstrated for a number of selected metal nuclei (25Mg, 27Al, 49Ti, 57Fe, 59Co, 61Ni, 91Zr, 103Rh, and 195Pt). Relations found empirically between chemical shifts and coordination number, oxidation number, and electronic configuration of a metal bound in a complex are emphasized. Furthermore, cases in which the chemical shifts of metal nuclei can be interpreted in terms of the energy difference of frontier orbitals are presented. This aspect leads to the establishment of a relationship between chemical reactivity and NMR parameters for a series of related compounds.

Maurice Vallino

Papers

Structure cristalline de CH3MgBr·3 C4H8O