Kremer Marius, Englert Ulli
Institut für Anorganische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
Acta Crystallogr E Crystallogr Commun. 2019 May 31;75(Pt 6):903-911. doi: 10.1107/S2056989019007461. eCollection 2019 Jun 1.
Six reaction products of Zn and Ni with pyridine-2,6-di-carb-oxy-lic acid (HLig), 4-chloro-pyridine-2,6-di-carb-oxy-lic acid (HLig) and 4-hy-droxy-pyridine-2,6-di-carb-oxy-lic acid (HLig) are used to pinpoint the structural consequences of crystal field stabilization by an incomplete shell. The pseudo-octa-hedral Zn coordination sphere in bis-(6-carb-oxy-picolinato)zinc(II) trihydrate, [Zn(CHNO)]·3HO or [Zn(HLig)]·3HO, (), is significantly less regular than that about Ni in the isostructural compound bis-(6-carb-oxy-picolinato)nickel(II) trihydrate, [Ni(CHNO)]·3HO or [Ni(HLig)]·3HO, (). The Zn complexes poly[(4-chloro-pyridine-2,6-di-carboxyl-ato)zinc(II)], [Zn(CHClNO)] or [Zn(Lig)] , (), and poly[[(4-hy-droxy-pyridine-2,6-di-carboxyl-ato)zinc(II)] monohydrate], {[Zn(CHNO)]·HO} or {[Zn(Lig)]·HO} , (), represent two-dimensional coordination polymers with chelating and bridging pyridine-2,6-di-carboxyl-ate ligands in which the coordination polyhedra about the central cations cannot be associated with any regular shape; their coordination environments range between trigonal-bipyramidal and square-pyramidal geometries. In contrast, the corresponding adducts of the diprotonated ligands to Ni, namely tri-aqua-(4-chloro-pyridine-2,6-di-carboxyl-ato)nickel(II), [Ni(CHClNO)(HO)] or [NiLig(OH))], (), and tri-aqua-(4-hy-droxy-pyridine-2,6-di-carboxyl-ato)nickel(II) 1.7-hydrate, [Ni(CHNO)(HO)]·1.7HO or [NiLig(OH))]·1.7HO, (), feature rather regular octa-hedral coordination spheres about the transition-metal cations, thus precluding the formation of analogous extended structures.
锌和镍与吡啶 - 2,6 - 二羧酸（HLig）、4 - 氯吡啶 - 2,6 - 二羧酸（HLig）以及4 - 羟基吡啶 - 2,6 - 二羧酸（HLig）的六种反应产物被用于确定不完全壳层晶体场稳定化的结构后果。三水合双（6 - 羧基吡啶甲酸根）锌（II），[Zn(CHNO)]·3HO 或 [Zn(HLig)]·3HO，（）中锌的伪八面体配位球，相较于同结构化合物三水合双（6 - 羧基吡啶甲酸根）镍（II），[Ni(CHNO)]·3HO 或 [Ni(HLig)]·3HO，（）中镍的配位球，规则性显著更低。锌配合物聚[（4 - 氯吡啶 - 2,6 - 二羧酸根）锌（II）]，[Zn(CHClNO)] 或 [Zn(Lig)] ，（），以及聚[[（4 - 羟基吡啶 - 2,6 - 二羧酸根）锌（II）]一水合物]，{[Zn(CHNO)]·HO} 或 {[Zn(Lig)]·HO} ，（），代表具有螯合和桥连吡啶 - 2,6 - 二羧酸根配体的二维配位聚合物，其中中心阳离子周围的配位多面体无法与任何规则形状相关联；它们的配位环境介于三角双锥和四方锥几何构型之间。相比之下，双质子化配体与镍的相应加合物，即三水合（4 - 氯吡啶 - 2,6 - 二羧酸根）镍（II），[Ni(CHClNO)(HO)] 或 [NiLig(OH))]，（），以及三水合（4 - 羟基吡啶 - 2,6 - 二羧酸根）镍（II）1.7水合物，[Ni(CHNO)(HO)]·1.7HO 或 [NiLig(OH))]·1.7HO，（），其过渡金属阳离子周围具有相当规则的八面体配位球，因此排除了形成类似扩展结构的可能性。
