Synthesis and Characterization of Cationic [Tris(pyrazolyl)methane]copper(I) Carbonyl and Acetonitrile Complexes

The reaction of [Cu(NCMe) 4 ]PF 6 with equimolar amounts of the tris(substituted-pyrazolyl)methane ligands HC(3,5-Me 2 pz) 3, HC(3-Phpz) 3, and HC(3-Bu t pz) 3 yields the respective salts {[HC(3,5-Me 2 pz) 3 ]Cu(NCMe)}PF 6, {[HC(3-Phpz) 3 ]Cu(NCMe)}PF 6, and {[HC(3-Bu t pz) 3 ]Cu(NCMe)}PF 6 . These complexes are unusually resistant toward reaction with dioxygen. These acetonitrile complexes react with carbon monoxide to yield the stable complexes {[HC(3,5-Me 2 pz) 3 ]Cu(CO)}PF 6, {[HC(3-Phpz) 3 ]Cu(CO)}PF 6, and {[HC(3-Bu t pz) 3 ]Cu(CO)}PF 6, respectively. The solid-state structures of {[HC(3-Bu t pz) 3 )]Cu(NCMe)}PF 6 ·CH 2 Cl 2 and {[HC(3-Bu t pz) 3 ]Cu(CO)}PF 6 have been determined by X-ray crystallography. The structures are very similar, with the Cu−N distances to the donor atoms of the HC(3-Bu t pz) 3 ligand 0.03 Å shorter in the carbonyl complex.