Cationic copper(I) and silver(I) nitrile complexes with fluorinated weakly coordinating anions: Metal–nitrile bond strength and its influence on the catalytic performance

Copper(I) and silver(I) complexes of formulae [Cu(NCCH3)4]+[A]− ([A]− = [B(C6F5)4]− (1), {B[C6H3(CF3)2]4}− (2), [(C6F5)3B–C3H3N2–B(C6F5)3]− (3), and [Ag(NCCH3)4]+[B(C6F5)4]− (4) are examined with particular emphasis on the strength of their M–N bond and its influence on the catalytic performance of these complexes in cyclopropanation and aziridination. To examine the strength of the M–N interactions, vibrational spectra of the related hydrogenated and deuterated species [Cu(NCCH3)4]+, [Cu(NCCD3)4]+, [Ag(NCCH3)4]+, and [Ag(NCCD3)4]+ are also determined. It is found that the metal–nitrile bond strength is an important factor for the catalytic activity of the respective complexes.