Potentially bidentate 4-diazopyrazol-5-one ligands carrying a range of substituents can readily be prepared by coupling arene diazonium salts on to the appropriate pyrazolones. Hydrocarbon-soluble versions are shown to be suitable reagents for the recovery of copper by solvent extraction from ammoniacal leach solutions, and potentially have greater resistance to chemical degradation than the β-diketones which have been used. Cobalt(III), nickel(II), copper(II) and zinc(II) complexes with 4-(4-tert-butylphenylazo)-3-methyl-1-phenyl-5-pyrazolone (HL) have been characterised by X-ray crystallography. The significant deviations from planar coordination geometry which are observed in [CuL2] and [CuL′2], where HL′ is 3-methyl-1-phenyl-4-phenylazo-5-pyrazolone, arise from interligand repulsion, and account for the relatively weak complexation and ease of stripping of copper from this class of extractant. The cobalt(III) complex [CoL3]·3MeOH and the high spin nickel(II) complex [NiL2(MeOH)2]·2MeOH both have approximately octahedral geometries, but show significantly different bite distances in the chelate rings. The zinc complex [ZnL2] has a pseudo-tetrahedral structure.
潜在双齿的4-二氮基
吡唑-5-酮
配体可以通过将
芳烃重氮盐偶联到适当的
吡唑酮上,方便地制备出各种取代基的衍
生物。溶于烃溶剂的版本被证明是从
氨浸出溶液中通过溶剂萃取回收
铜的合适试剂,并且相较于已使用的
β-二酮,可能具有更强的
化学降解抵抗性。4-(4-
叔丁基苯基偶氮)-3-甲基-1-苯基-5-
吡唑酮(HL)与
钴(III)、
镍(II)、
铜(II)和
锌(II)的配合物已通过X射线晶体学进行表征。在[Cu
L2]和[CuL′2]中观察到的显著非平面配位几何形状的偏离,源于
配体间的排斥作用,并解释了
铜相对较弱的配位性和从这一类萃取剂中去除
铜的容易性。
钴(III)配合物[CoL3]·3MeOH和高自旋
镍(II)配合物[Ni
L2(MeOH)2]·2MeOH都具有近似的八面体几何形状,但在螯合环中的咬合距离上表现出显著不同。
锌配合物[Zn
L2]则具有伪四面体结构。