Christian Butzlaff

Isolation of a spin-frustrated imidazolate-bridged trinuclear copper(II) complex potentially relevant to the multicopper oxidases

The reaction of Cu(MeCO2)2·H2O with 1,4,7-trimethyl-1,4,7-triazacyclononane (L) and imidazole (ImH) in methanol affords, in the presence of a small amount of triethylamine and NaClO4, the blue trinuclear complex [L3Cu3(Im)3](ClO4)3 which has been characterized by X-ray crystallography, EPR and magnetic susceptibility measurements to be a spin-frustrated triangular imidazolate-bridged copper(II) complex without any µ3-X ligand.

A structural and magnetochemical study of some copper(II) complexes containing the ligands 1,4,7-triazacyclononane-N-acetate (L1) and N-(2-hydroxybenzyl)-1,4,7-triazacyclononane (HL2)

The tetradentate macrocyclic ligands 1,4,7-triazacyclononane-N-acetate (L1) and N-(2-hydroxybenzyl)-1,4,7-triazacyclononane (HL2) react in methanol with CuCl2 or Cu(ClO4)2·6H2O in the absence or presence of LiOH·H2O with formation of the following complexes containing square based pyramidal Cu(II)ions: [L1CuCl] (1), [L1CuCl]LiCl·2H2O (2), [L1Cu](ClO4) (3) and [L22Cu2](ClO4)2 (4). Complexes 2 and 4 have been characterized by single crystal X-ray crystallography; the structure of 3 has been reported previously [3]. Crystal data: 2, space group P21/c, a = 11.674(4), b = 7.543(2), c = 17.560(5) A, β = 106.59(8)°, V = 1481.9(7) A3 Z = 4, Dcalc = 1.63 g cm−3, R = 0.044 based on 2499 reflections; 4, space group Pbca, a = 17.742(4), b = 10.335(2), c = 17.742(4) A, V = 3253(1) A3, Dcalc = 1.62, Z = 4, R = 0.048 based on 2147 reflections. From temperature dependent magnetic susceptibility measurements (2–293 K) weak intermolecular antiferromagnetic exchange coupling has been established for 1 and 2, whereas for the helical chain structure 3 weak ferromagnetic exchange coupling has been observed. In dinuclear 4 strong antiferromagnetic intramolecular coupling leads to an S = 0 ground state.

Synthesis, molecular and electronic structure of complexes [LNaMIVNaL](MRu,Os; H3L = 1,4,7-tris(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane)

The trinuclear complexes [LNaMIVNaL](M = Ru 1, Os 2) where L represents the hexadentate ligand 1,4,7-tris(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane have been synthesized and 1 has been characterized by X-ray crystallography; complex 1 contains an octahedral MIVS6 central core and two trigonal-prismatic terminal LNa units with an N3S3 donor set; the electronic structure of the MIVS6 core (M = Ru, Os), has been established as S= 1 by temperature-dependent magnetic susceptibility measurements.