Piro O E, Echeverría G A, Baran E J
Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and IFLP(CONICET), C.C. 67, 1900 La Plata, Argentina.
Centro de Química Inorgánica (CEQUINOR), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 962, 1900 La Plata, Argentina.
Acta Crystallogr E Crystallogr Commun. 2018 Jun 8;74(Pt 7):905-909. doi: 10.1107/S2056989018008022. eCollection 2018 Jul 1.
We show here that the phenomenon of spontaneous resolution of enanti-omers occurs during the crystallization of the sodium and rubidium double salts of the transition metal complex tris-(oxalato)ferrate(III), namely sodium penta-rubidium bis-[tris-(oxalato)ferrate(III)], NaRb[Fe(CO)]. One enanti-omer of the salt crystallizes in the cubic space group 432 with = 4 and a Flack absolute structure parameter = -0.01 (1) and its chiral counterpart in the space group 432 with = -0.00 (1). All metal ions are at crystallographic special positions: the iron(III) ion is on a threefold axis, coordinated by three oxalate dianions in a propeller-like conformation. One of the two independent rubidium ions is on a twofold axis in an eightfold coordination with neighbouring oxalate oxygen atoms, and the other one on a threefold axis in a sixfold RbO coordination. The sodium ion is at a site of point group symmetry in a trigonal-anti-prismatic NaO coordination.
我们在此表明，对映体自发拆分现象发生在过渡金属配合物三（草酸根）铁（III）的钠铷复盐（即五铷合二[三（草酸根）铁（III）钠]，NaRb[Fe(CO)]）的结晶过程中。该盐的一种对映体在立方空间群432中结晶，晶胞参数(Z = 4)，Flack绝对结构参数(x = -0.01(1))，其手性对应物在空间群432中结晶，(x = -0.00(1))。所有金属离子都处于晶体学特殊位置：铁（III）离子位于三重轴上，由三个呈螺旋状构象的草酸根二价阴离子配位。两个独立铷离子中的一个位于二重轴上，与相邻草酸根氧原子形成八重配位，另一个位于三重轴上，形成六重(RbO)配位。钠离子处于三角反棱柱形(NaO)配位的(C_{3h})点群对称位置。
