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Cationic bis(alkyne)copper(I) carbonyl and bis(alkyne)copper(I) isocyanide complexes have been synthesized from the precursor (cyclooctyne)2CuBr. [Cu(cyclooctyne)2(CO)][SbF6] and [Cu(cyclooctyne)2(CNtBu)][SbF6] have trigonal-planar and three-coordinate copper centers. The copper carbonyl complex [Cu(cyclooctyne)2(CO)][SbF6] displays its C–O stretching frequency in the “nonclassical” metal carbonyl region (2171 cm–1), and the analogous copper(I) isocyanide complex [Cu(cyclooctyne)2(CNtBu)][SbF6] also has an unusually high CN stretching band at 2230 cm–1. The reaction of 3,5-Me2C6H3NH2 and 4-tBuC6H4NH2 with [Cu(cyclooctyne)2(CO)][SbF6] led to CO displacement rather than addition to CO. CNtBu reacts with [Cu(cyclooctyne)2(CO)][SbF6] to afford [Cu(cyclooctyne)2(CNtBu)][SbF6]. The syntheses of [Cu(cyclooctyne)(CNtBu)2][SbF6] and [Cu(CNtBu)4][SbF6] from the (cyclooctyne)2CuBr precursor are also reported.

The tris(alkyne) copper complex [(cyclooctyne)3Cu][SbF6] has been synthesized using cyclooctyne and in situ generated CuSbF6. Tris(alkyne) silver complexes [(cyclooctyne)3Ag]+ involving weakly coordinating counterions such as [SbF6]− and [PF6]− have also been isolated in good yield using cyclooctyne and commercially available AgSbF6 and AgPF6. These coinage metal tris(alkyne) adducts have trigonal-planar metal sites. The alkyne carbon atoms and the metal site form distorted spoke-wheel (rather than upright trigonal-prismatic) structures in the solid state. In [(cyclooctyne)3Cu][SbF6], these distortions result in a propeller-like arrangement of alkynes. A cationic gold(I) complex having two alkynes has been prepared by a reaction of equimolar amounts of Au(cyclooctyne)2Cl and AgSbF6 in dichloromethane. The gold atom of [(cyclooctyne)2Au]+ coordinates to the cyclooctynes in a linear fashion, while the carbon atoms of the alkyne groups form a tetrahedron around gold(I). Optimized geometries of cationic [(cyc...