A unique bonding of indole to a metal ion has been established. Two new tridentate N ligands with a pendent indole ring gave Cu(I) complexes 1 and 2, the latter of which exhibits the new form of bonding between the Cu(I) ion in a distorted tetrahedral geometry and the indole C(2)-C(3) moiety. The bond is dependent upon the length of the side chain and therefore the accessibility of the ring to the metal center.