Structure and characterization of non-cyclic tetraaza complexes of copper(II) and their reactions with nitric oxide
摘要:
[Cu(bapP)ClO4](+) (1) and [Cu(bapp)Cl](+) (2) were prepared by the reaction of 1,4-bis(3-aminopropyl)piperazine (bapp) with copper acetate and copper chloride in the presence of sodium perchlorate, respectively, and structurally characterized. Complex I has a square-pyramidal geometry, whereas [Cu(3,2,3-tet)(ClO4)](+) (A) has a polymeric octahedral geometry in its X-ray crystal structure. Complex I is stable against disproportionation, whereas complex A is unstable in the mono-valent Cu(l) state. An aqua ligand on complex I in aqueous solution is substituted by NO with kinetic constants of k(f) = 43 +/- 2 M-1 s(-1) and k(b) = (8.8 +/- 0.2) X 10(-2) s(-1) at 25 degreesC, whereas there were no spectral changes observed for complex A in saturated NO solution. (C) 2004 Elsevier B.V. All rights reserved.