Heterobinuclear Adducts of Copper Tetradentate Schiff Bases with Metal Hexafluoroacetylacetonates
A series of heterobinuclear complexes was prepared by the reaction of copper tetradentate Schiff base complexes, Cu(TSB), with metal hexafluoroacetylacetonates, M(hfa)2 (M = Ni(II), Co(II), Fe(II), Mn(II)). The Schiff base ligands, H2((prp)2en) and H2((prp)2pr), were prepared from the condensation of o-hydroxypropiophenone, Hprp, with ethylenediamine, en, or 1,3-propylenediamine, pr, respectively. The crystal structures of three of the complexes, Cu((prp)2en)Fe(hfa)2, Cu((prp)2pr)Fe(hfa)2, and Cu((prp)2pr)Co(hfa)2, were determined and refined to R values of 6.1, 8.3, and 6.3% for 1107, 2258, and 1411 reflections, respectively. Cu((prp)2en)Fe(hfa)2 crystallizes in P21/c, Z = 4, with a = 13.576 (7) Å, b = 20.365 (5) Å, c = 12.606 (7) Å, and β = 97.70 (5)°. Cu((prp)2pr)Fe(hfa)2 and Cu((prp)2pr)Co(hfa)2 crystallize in P1, Z = 2, with a = 11.630 (4) Å, b = 12.443 (6) Å, c = 13.897 (4) Å, α = 90.83 (5)°, β= 95.26 (4)°, and γ = 116.19 (4)° and a = 11.821 (3) Å, b = 12.402 (5) Å, c = 13.885 (6) Å, α = 91.64 (3)°, β = 95.64 (3)°, and γ = 116.75 (3)°, respectively. The magnetic susceptibilities of all complexes were measured between 4 and 110 K. The strength of antiferromagnetic coupling, J, is shown to depend on the angle, Φ, between the O(1)-Cu-O(2) and O(1)-M-O(2) planes and on the Cu-O-M angle. Thus, a 5° increase in Φ in the pr series of Cu-Fe compounds over the value in the en series is accompanied by an increase in the quartet-sextet separation, -5J, from 30 to 115 cm-1. This series better models some of the electronic properties of cytochrome oxidase than a wide variety of literature binuclear complexes, and it lends support to a CuOFe center in the enzyme with a metal-metal separation of a little over 3 Å. © 1987 American Chemical Society.
G. A. Brewer and E. Sinn, "Heterobinuclear Adducts of Copper Tetradentate Schiff Bases with Metal Hexafluoroacetylacetonates," Inorganic Chemistry, American Chemical Society (ACS), Jan 1987.
The definitive version is available at https://doi.org/10.1021/ic00257a014
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© 1987 American Chemical Society (ACS), All rights reserved.