Synthesis and structural characterization of isolable phosphine coinage metal π-complexes

Abstract

The chemical community has recently witnessed a dramatic increase in the application of cationic gold(I)-phosphine complexes as homogeneous catalysts for organic synthesis. The majority of gold(I)-catalyzed reactions rely on nucleophilic additions to carbon-carbon multiple bonds, which have been activated by coordination to a cationic gold(I) catalyst. However, structural evidence for coordination of cationic gold(I) complexes to alkynes has been limited. Here, we report the crystal structure of a gold(I)-phosphine 2 -coordinated alkyne. Related Ag(I) and Cu(I) complexes have been synthesized for comparison. The crystallization of these complexes was enabled by tethering a labile alkyne ligand to a strongly coordinating triarylphosphine. This approach also proved applicable to crystallization of the first gold(I)-phosphine 2 -coordinated alkene.alkyne complexes ͉ DFT calculations ͉ gold catalysts ͉ homogenous catalysis ͉ x-ray structures

Synthesis and Study of Cationic, Two‐Coordinate Triphenylphosphine– Gold–π Complexes

“…Conversely, mononuclear, cationic, two-coordinate goldp complexes containing a triphenylphosphine ligand have not been isolated. [17] Although monomeric triphenylphosphine-gold-p complexes have escaped isolation, a number of these complexes have been purportedly generated in situ from reaction of a p ligand with either a mixture of [(PPh 3 )AuCl] and silver salt or with a single-component gold complex, such as [(PPh 3 )AuNTf 2 ]. [18][19][20][21][22][23] However, there are a number of inconsistencies in the reported spectroscopy and solution behavior of these complexes that warrant further investigation.…”

Recent developments in gold-catalyzed cycloaddition reactions

“…Although these metal carbophilic catalysts also coordinate to alkenes, dienes and allenes in a similar way [18–22], nucleophiles seem to have a kinetic preference for attacking activated alkynyl systems, which warrants high chemoselectivities.…”

Triazole–Au(I) complex as chemoselective catalyst in promoting propargyl ester rearrangements

“…The actual catalysts involved in alkyne and alkene activation are of the type [L–Au] + , with the open coordination site on the opposite side of the ligand (L) for substrate binding [5–6]. The recent success in obtaining the complexes of the alkyne-coordinated [L–Au] + , reported by Toste and coworkers, greatly supported this mechanistic model [16]. Generally, the PR 3 compounds can be applied as the ligand in Au(I) catalysis.…”