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Metal Complexes of Small Cycloalkynes and Arynes
Author(s) -
Bennett Martin A.,
Schwemlein Heinz P.
Publication year - 1989
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.198912961
Subject(s) - aryne , chemistry , transition metal , metal , ligand (biochemistry) , molecule , triple bond , stereochemistry , crystallography , medicinal chemistry , double bond , polymer chemistry , organic chemistry , catalysis , biochemistry , receptor
Cyclooctyne is the smallest unsubstituted cycloalkyne that can be isolated in the free state and it is more reactive than acyclic alkynes towards transition metal complexes. Smaller cycloalkynes such as cycloheptyne, cyclohexyne, benzyne and cyclopentyne, which are transient molecules in the free state, can be stabilized by coordination either to mononuclear, electron‐rich, transition metal‐containing fragments, e.g. [ZrCp 2 (PMe 3 )] and M(PR 3 ) 2 (M = Ni, Pt), or by formation of dinuclear or polynuclear metal complexes, e.g. [Os 3 H 2 (CO) 9 (C 6 H 4 )] and [Pt 2 (μ‐PPh 2 )(μ‐C 5 H 6 )(PPh 3 ) 3 ]. The alkynes can donate between two and four π‐electrons to the metal centers, the higher number being favored for the early transition metals. The metal‐cycloalkyne and metal‐aryne bonds in the mononuclear complexes readily insert molecules containing CO, CC, CC and CN bonds, a feature that may be useful in organic synthesis. The highly unsaturated species 1, 4‐benzdiyne acts as a bridging ligand between two metal centers in [{Ni(Cy 2 PCH 2 CH 2 PCy 2 )} 2 (μ‐C 6 H 2 )].