David Schnieders, A. Hammerschmidt, Michael Merkel
Dec 1, 2008
Citations
0
Influential Citations
12
Citations
Journal
Zeitschrift für anorganische und allgemeine Chemie
Abstract
Starting from the tripodal tetradentate ligands -(3,5-dibromo-2-hydroxybenzyl)(2-hydroxybenzyl)(2-pyridyl)methylamine (H2L1), (3,5-dibromo-2-hydroxybenzyl)(2-hydroxy-5-nitrobenzyl)(2-pyridyl)methylamine (H2L2), and (3,5-dichloro2-hydroxybenzyl)(2-hydroxy-5-nitrobenzyl)(2-pyridyl)methylamine (H2L3) the new isostructural dinuclear zinc compounds [Zn2(L1)2]·N(CH2CH3)3 (1), [Zn2(L2)2]·2CH3OH (2) and [Zn2(L3)2]·C4H10O (3) were synthesized. Due to their enzyme-like trigonal bipyramidal N2O3 coordination environment of the zinc ions and the similar Zn···Zn distances the complexes can be considered to be structural models for the active sites in phospholipase C and nuclease P1. With H2L3 also the dinuclear complex [Co2(L2)2(CH3OH)]·2CH3OH·0.5C4H10O (4) could be prepared. The new compounds were isolated and characterized by single crystal X-ray crystallography as well as infrared spectroscopy. The cobalt compound 4 was additionally characterized by UV-Vis spectroscopy and magnetic measurements. 1 crystallizes in the monoclinic space group P21/n with a = 11.2814(2), b = 28.6154(2), c = 13.1866(3) A, β = 96.995(1)°, V = 4225.2(2) A3, Z = 4. 2 and 3 are monoclinic, space group C2/c with a = 23.084(5), b = 9.232(2), c = 21.849(4) A, &β; = 96.83(3)°, V = 4623(2) A3, Z = 4, and a = 22.7834(3), b = 9.2463(1), c = 21.6351(3) A, &β; = 97.592(1)°, V = 4517.7(2) A3, Z = 4, respectively. 4 crystallizes in the monoclinic space group I2/a with a = 22.4680(4), b = 20.5517(4), c = 22.8910(6) A, &β; = 111.938(1)°, V = 9804.7(4) A3, Z = 8. 4 shows an effective magnetic moment of 6.72 μB at 300 K which clearly indicates the presence of two cobalt(II) high spin ions with Curie-Weiss behaviour above 80 K. At lower temperatures a decrease of the effective magnetic moment was observed.