Tetrahedral and octahedral cobalt(II) in hexaaquacobalt tetrachlorocobaltate–18-crown-6–acetone

Abstract

18-crown-6. acetone, determined by heavy-atom techniques and refined by least-squares methods using diffractometer data to R l = 4.3% (4246 observed reflections), includes cobalt(II) in two coordination geometries: a tetrachlorocobaltate anion and a hexaaquacobalt cation. The crown ether ring does not incorporate the metal into its cavity.

Structure of thorium nitrate–1,4,7,10,13,16-hexaoxacyclooctadecane–water (1/1/3), [Th(OH2)3(NO3)4].18-crown-6 at 123 K

“…The six O atoms participate in hydrogen bonds to three H atoms from two water molecules on one side of the inversion center and three H atoms from a different Th(NO3)4(OH2) 3 unit on the other. The three independent H...O(crown) separations are 1.7010 (7) The bond distances and angles in the crown ring are nearly identical with those found for the free crown at 100 K given below in square brackets (Maverick, Seiler, Schweizer & Dunitz, 1980) .18-crown-6.acetone (Vance, Holt, Pierpont & Holt, 1980). The most commonly observed crown-ether conformation in its complexes with ions and hydrogen-bond donors is the symmetrical Dad (ag+aag-aag+aa) form (Uiterwijk et al, 1983).…”

Transition-metal–crown-ether complexes. III. Seven-coordinate CoII in dinitratocobalt(II)–12-crown-4 and diaquacobalt(II) dinitrate–15-crown-5

“…18-crown-6. acetone (Vance, Holt, Pierpont & Holt, 1980) where two coordination geometries were observed for Co n . Other structures have shown direct involvement of the transition metal with the polyether oxygens, either completing the coordination sphere of the metal: Mn(12-crown-4)2(Br3) 2 (Pierpont & Blackmer, 1979), or partially completing it: CuC12-(12-crown-4) (van Remoortere, Boer & Steiner, 1975).…”

“…18-crown-6. acetone (Vance, Holt, Pierpont & Holt, 1980) displays Co u in octahedral Co(H20)6 and tetrahedral CoCI 4 ions, both uninvolved with 18-crown-6 (cavity diameter, 2.6-3.2/~,).…”

“…Those complexes which have been examined structurally have shown a wide variety of modes of involvement with the crown ether. Some structures have shown that the transition metal achieves normal coordination geometry with water or nitrate ions which * Part I: Vance, Holt, Pierpont & Holt (1980). Part II: Vance, Holt, Varie & Holt (1980).…”

Structure of hexaaquamanganese(II) perchlorate–18-crown-6

“…Transition-metal complexes with crown ethers have received little attention in the literature (Vance, Holt, Pierpont & Holt, 1980;and references therein). We have determined the structures of a series of these complexes to examine structural consequences of change of ring size and metal ion.…”