Synthesis and X-Ray Crystal Structure of the Double Salt, Bis(tetramethylammonium) Triiodide trans-Diiodobis(ethanedial dioximato(1 –)-N,N′)cobaltate(III). (N(CH3)4)2I3(CoI2(GH)2)

Abstract

A “one-pot” reaction involving cobalt(II) nitrate hexahydrate, iodine, tetramethylammonium iodide and ethanedial dioxime (or glyoxime, GH2) in water/methanol solution has afforded the novel double salt, bis(tetramethylammonium) triiodide trans-diiodobis(ethanedial dioximato)cobaltate(III), (N(CH3)4)2I3(CoI2(GH)2). The structure of the salt was determined from single crystal X-ray diffraction data. Crystal data: orthorhombic space group Pnma; C12H30CoI5N6O4, Mr = 1015.84; a = 10.60(1), b = 12.531(5), c = 21.47(2) Å; V = 2851.83 Å3; Z = 4; Dc = 2.36 Mg m-3. The structure consists of three distinctive molecular species, namely, (N(CH3)4)+, I3 -, and (CoI2(GH)2)-. The cobaloximatic anion contains CoIII in the usual (4+2) octahedral ligand field of four chelating N atoms lying within the molecular equatorial plane, and two iodides occupying the apical positions. The atomic triads, I -Co-I and I- I - I, are slightly bent by an angle of 177.3° and 176.8°, respectively. Two symmetrical O-H-O bridges with slightly diverging O · · · O separations (2.492 and 2.516 A) are effective within the cobaloximatic anion. Van der Waals type intermolecular interactions occur only between the I atoms of adjacent I3 - and ICol units. These interactions give rise to the formation of “stripes” that propagate throughout the structure, parallel to the crystallographic ac plane. There are no interactions amongst ICol triads in this material.