The stereochemical preferences of copper complexes of 2,6-bis(3-tert-butylpyrazolyl)pyridine (L1But) have been investigated. The single crystal X-ray structures of [Cu(μ-Cl)(L1But)}2][BF4]2 (3a), [Cu(μ-Cl)(OH2)(L1But)}2][BF4]2 (3b) and [Cu(NCMe)2(L1But)][BF4]2 (4) show distorted tetragonal geometries at Cu, with one or two axial solvent and/or BF4− ligands. The Cu centres in 3a and 3b are weakly associated into dimers, through axial Cu–Cl⋯Cu bridging. Single
crystals of 4 undergo an unusual substitution of their MeCN ligands upon exposure to air, yielding [Cu(OH2)2(L1But)][BF4]2 (1). A combination of UV/vis, EPR and conductivity studies has shown that Cu(II)-bound L1But is labile in solution. Susceptibility data show that the Cu ions in 3a are weakly antiferromagnetically coupled through the Cl− bridges, although this compound exhibits a spin-triplet EPR spectrum in the solid. Cyclic voltammograms of 3a and 4 in MeCN–0.1 M NBun4BF4 confirm the lability of Cu-bound L1But.
研究了 2,6-双(3-叔丁基
吡唑基)
吡啶(L1But)
铜配合物的立体
化学偏好。[Cu(μ-Cl)(L1But)}2][ ]2(3a)、[Cu(μ-Cl)(OH2)(L1But)}2][ ]2(3b)和[Cu(NCMe)2(L1But)][ ]2(4)的单晶 X 射线结构显示了 Cu 的畸变四方几何结构,其中有一个或两个轴向溶剂和/或
BF4 配体。3a 和 3b 中的
铜中心通过轴向的 Cu-Cl⋯Cu 桥接,微弱地结合成二聚体。4 的单晶在暴露于空气中时,其 MeCN
配体会发生不寻常的置换,生成 [Cu(OH2)2(L1But)][ ]2(1)。结合紫外/可见光、电致发光和电导研究表明,与 Cu(II) 结合的 L1But 在溶液中是易变的。电感数据显示,尽管 3a 中的 Cu 离子在固体中呈现自旋三重 EPR 光谱,但通过 Cl- 桥耦合的反
铁磁性很弱。3a 和 4 在 MeCN-0.1 M NBun4 中的循环伏安图证实了与 Cu 结合的 L1But 的惰性。