INTERPRETATION OF ELECTRONIC AND EPR-SPECTRA OF COPPER(II) AMINE COMPLEXES - A TEST OF THE MM-AOM METHOD

The strain energy minimized structures (MM) of a series of copper(II) tetraamines ([Cu((R)-ahaz)((S)-ahaz)](2+), (R)-ahaz (1)= (R)- 3-aminoh exahydroazepine, (S)-ahaz (2)= (S)-3 -aminohexahydroazepine; [Cu((S)-a haz)(2)(OH2)](2+); [CU(mn[13]aneN(4))(OH2)(2)](2+), mn[l3]aneN(4) (3) = 2-methyl-12-nitro-l,4,7,10-tetraazacyclotridecane; [Cu(mn[l3]aneN(4) )(OH2)](2+); [Cu(mn[14]aneN(4))(OH2)](2+), mn[l4]aneN(4) (4)= -methyl- 6-nitro-1,4,8,11-tetraazacyclotetradecane; [Cu(mn[15]aneN(4))(OH2)](2), mn[ 15]aneN(4) (5)= methyl-10-nitro-1,4,8,12-tetraazacyclopentadeca ne; [Cu(mn[15]aneN(4))(OH2)(2)](2+); [Cu(mn[16]aneN(4))(OH2)](+), mn[1 6]ane N-4 (6) = 3-methyl-3-nitro-1,5,9,13-tetraazacyclohexadecane; [Cu (en)(2)(OH2)(2)](2+), en (7) = ethane-1,2-diamine), with square planar , square pyramidal, and distorted octahedral chromophores exhibiting v arious degrees of tetrahedral distortion of the central coordination p lane, are in good agreement with published X-ray structures (where ava ilable) and the two crystal structures reported ip this paper. [Cu(2)( 2)(ClO)(4)](ClO4) crystallizes in the orthorhombic space group P2(1)2( 1)2(1), with a 18.194(4) Angstrom, Z = 4, and R, = 0.061. [Cu(5)(C1)21 2and0 crystallizes in the 6.884(2) W, b = 9.090(3) Angstrom, c = 9.21 4(2) Angstrom, cc = 105.13(2)0, P = 107.40(2)'', y = 107.85(2)0, Z = 1 , and R, = 0.022. The spin Hamiltonian parameters and electronic trans itions, estimated with the angular overlap model (AOM) based on the st rain energy minimized structures of the chromophores, where generally water is used as axial ligand (MM-AOM), are in reasonable agreement wi th the calculated spectroscopic parameters based on experimental struc tures (AOM) and with the experimental spectroscopic data (UV-vis-near- IR and EPR spectra ofsingle crystals, powders, glasses, and solutions) . The calculated spectroscopic data are based on a constant set of ele ctronic parameters which depend on the degree of substitution of the a mine, on the Cu-N bond length, and on the degree of misdirected valenc es.