Copper(l) complexes, copper(I)/O2 reactivity, and copper(II) complex adducts, with a series of tetradentate tripyridylalkylamine tripodal ligands

Copper(I) and copper(II) complexes possessing a series of related ligands with pyridyl-containing donors have been investigated. The ligands are tris(2-pyridylmethyl)amine (tmpa). bis[(3-pyridyl)methyl]-2-(2-pyridyl)ethylamine (pmea). bis[2-(2-pyridyl)ethyl]-(2-pyridyl)methylamine (pmap), and tris[2-(3-pyridyl)ethyl]amine (tepa). The crystal structures of the protonated ligand H(tepa)ClO4, the copper(l) complexes [Cu(pmea)]PF6 (1b-PF6), [Cu(pmap)]- PF6 (1c-PF6), and copper(IT) complexes [Cu(pmea)Cl]ClO4.H2O (2b-ClO4.H2O). [Cu(pmap)Cl](ClO4.H2O (2c-ClO4 .H2O). [Cu(pmap)Cl]ClO4 (2c-ClO4). and [Cu(pmea)F](2)(PF6)(2) (3b-PF6) were determined. Crystal data: H(tepa)ClO4, formula C21H25ClN4O4 triclinic space group P (1) over bar. Z = 2, a = 10.386(2) Angstrom, b = 10.723(2) Angstrom, c 11.663(2) Angstrom, alpha = 108.77(3)degrees, beta = 113.81(3)degrees gamma = 90.39(3)degrees: 1b-PF6, formula C19H20CuF6N4P, orthorhombic space group Pbca, Z = 8, a = 14.413(3) Angstrom, b = 16.043(3) Angstrom, c = 18.288(4) Angstrom, alpha = beta = gamma = 90 degrees; (1c-PF6), formula C20H22CuF6N4P, orthorhombic space group Pbca. Z = 8, a = 13.306(3) Angstrom. b = 16.936(3) Angstrom, c = 19.163-(4) Angstrom, alpha = beta = gamma = 90 degrees: 2b-ClO4.H2O, formula C19H22Cl2CuN4O5, triclinic space group P (1) over bar, Z = 4, a = 11.967-(2) Angstrom, b = 12.445(3) Angstrom, c = 15.668(3) Angstrom, alpha = 84.65(3)degrees, beta = 68.57(3)degrees, gamma = 87.33(3)degrees: 2c-ClO4.H2O, formula C20H24Cl2CuN4O5, monoclinic space group P2(1)/c, Z = 4, a = 11.2927(5) Angstrom, b = 13.2389(4) Angstrom, c = 15.0939(8) Angstrom, alpha = gamma = 90 degrees, beta = 97.397(2)degrees; 2c-ClO4, formula C20H22Cl2CuN4O4. monoclinic space group P2(1)/c, Z = 4, a = 8.7682(4) Angstrom, b = 18.4968(10) Angstrom, c = 13.2575(8) Angstrom. alpha = gamma = 90 degrees, beta = 94.219(4)degrees; 3b-PF6, formula [C19H20-CuF7N4P](2). monoclinic space group P2(1)/n, Z = 2. a = 11.670(5) Angstrom. b = 12.752(5) Angstrom, c = 15.424(6) Angstrom, alpha = gamma = 90 degrees, beta = 109.56(3)degrees. The oxidation of the copper(I) complexes with dioxygen was studied. [Cu(tmpa)(CH3-CN)](+) (la) reacts with dioxygen to form a dinuclear peroxo complex that is stable at low temperatures. In contrast, only a very labile peroxo complex was observed spectroscopically M wen Ih was reacted with dioxygen at low temperatures using stopped-flow kinetic techniques. No dioxygen adduct was detected spectroscopically during the oxidation of Ic, and Id was found to be unreactive toward dioxygen. Reaction or dioxygen with 1a-PF6, 1b-PF6, and 1c-PF6 at ambient temperatures leads to fluoride-bridged dinuclear copper(II) complexes as products. All copper(II) complexes were characterized by UV-vis, EPR , and electrochemical measurements. The results manifest the dramatic effects of ligand variations and particularly chelate ring size on structure and reactivity.