A series of doubly pyridazine-bridged dicobalt(II) macrocyclic complexes, 1–7, is reported. The pyridazine-containing Schiff-base macrocycle L1 [derived from the (2 + 2) condensation of 3,6-diformylpyridazine and 1,3-diaminopropane] provides four nitrogen donor atoms, disposed in an approximately square-planar manner, to each cobalt ion. Variation of the axial donors alters the spin state of the cobalt(II) ions from high spin, [Co2L1(H2O)4](ClO4)4 (2), [Co2L1(H2O)4](S2O6)2·4(H2O) (3·8H2O), [Co2L1(N3)2](ClO4)2 (4) and [Co2L1(NCO)3]ClO4
(5), to spin crossover, [Co2L1(MeCN)4](ClO4)4 (1·4MeCN) and [Co2L1(NCS)2(SCN)2] (6), to low spin, [Co2L1Cl2](ClO4)2 (7). Detailed magnetic susceptibility studies have yielded small, negative 2J values (−7 to −20 cm−1) for complexes 2 to 5. Compounds 1, 1·4MeCN and 6 are rare examples of binuclear complexes displaying simultaneous spin crossover (3/2 ⇔ 1/2) at high temperatures and antiferromagnetic exchange of the low-spin d7–d7
ions at low temperatures (2J
=
−10 to −14 cm−1).
报道了一系列双
哒嗪桥联的二
钴 (II) 大环配合物 1-7。含
哒嗪的希夫碱大环L1[衍生自3,6-二甲酰
哒嗪和1,3-二
氨基
丙烷的(2+2)缩合]为每个
钴提供四个氮供体原子,以近似正方形平面的方式布置离子。轴向供体的变化改变了高自旋
钴(II)离子的自旋状态,[Co2L1(
H2O)4](
ClO4)4 (2)、[Co2L1( )4](S2O6)2·4( ) ) (3·8 ), [Co2L1(N3)2]( )2 (4) 和 [Co2L1(NCO)3]
(5), 自旋交叉, [Co2L1(MeCN)4]( )4 (1·4MeCN) 和 [Co2L1(
NCS)2(SCN)2] (6), 低自旋, [Co2L1Cl2]( ) 2(7)。详细的磁化率研究得出了配合物 2 至 5 的小负 2J 值(−7 至 -20 cm−1)。化合物 1、1·4MeCN 和 6 是显示同时自旋交叉的双核配合物的罕见例子(3/2 ⇔ 1/2) 在高温和低自旋 d7–d7 的反
铁磁交换下
低温离子(2J
=
−10 至 −14 cm−1)。