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On the Influence of Heteroatoms in α‐ and β‐Functionalized Alkyl Transition‐Metal Compounds
Author(s) -
Steinborn Dirk
Publication year - 1992
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199204011
Subject(s) - heteroatom , homoleptic , chemistry , reactivity (psychology) , alkyl , transition metal , main group element , cationic polymerization , methylene , ligand (biochemistry) , stereochemistry , medicinal chemistry , metal , organic chemistry , catalysis , biochemistry , alternative medicine , receptor , pathology , medicine
The first homoleptic trimethylsilylmethyl transition‐metal complexes were synthesized about 20 years ago in the research groups of Wilkinson and Lappert, resulting in a significant advance in the understanding of the thermodynamic and kinetic stability of transition‐metal‐carbon σ bonds. The relatively high thermal stability of these bonds provides a dramatic contrast to the Köbrich lithium carbenoids XCH 2 Li, known for about 30 years and famous for their extraordinarily high reactivity. Both compound classes illustrate that introduction of a heteroatom into an alkyl ligand can have a profound influence on the structure, stability, and reactivity of an alkylmetal compound, opening the possibility of entirely new reactions. Because of their simple and unambiguous structure, α‐ and β‐heteroatom‐substituted transitionmetal compounds containing the unit [MCH 2 Y] or [MCH 2 CH 2 –Y] (where Y is an element from the 4th–7th main groups or groups 14–17, not including C ) are particularly suitable for studying effects of the nature of a heteroatom center (neutral/cationic, coordinatively saturated/Lewis basic) on structure, stability, and reactivity as a function of the type of complex, the nature of M, and the number of methylene groups separating M and Y. The diversity of stabilizing and destabilizing influences emanating from the heteroatom center generally produces a broad spectrum of reactivity and stability. This is reflected in an impressive way in homogeneous catalysis, where functionalized alkylmetal compounds arise as intermediates, as well as in the electronic influences of functionalized alkyl ligands, which are determined largely by the nature of the heteroelement present.