Zur Kenntnis von Unordnungsphänomenen bei Oxiden mit dem „Schmetterlingsmotiv”︁ Über Rb₂K₄[O₂CoOCoO₂]

Abstract

Rb2K4Co2O5 wurde erstmals durch Erhitzen inniger Gemenge der binären Oxide in Form von dunkelroten Einkristallen und Pulver erhalten (vor Verreiben Rb:K:Co = 1,2:3,2:1; Ni‐Zylinder, 570°C, 20d). Die Strukturaufklärung [Vierkreisdiffraktometerdaten; PW 1100; AgK α−‐Strahlung; 401 von 607 I0 (hkl); R = 9,9%; Rw=5,5%; Raumgruppe P42/mnm; Z = 2; a = 674,2(4), c = 1172,2(6) pm] belegt die Isotypie zu K2Na4Co2O5, Rb2Na4Co2O5 [2] und K2Na4Be2O5 [3]. Der Madelunganteil der Gitterenergie, MAPLE, Effektive Koordinationszahlen, ECoN, diese über Mittlere Fiktive Ionenradien, MEFIR, sowie die Ladungsverteilung, ΣQ, wurden berechnet. Ein Isotypievergleich mit Rb2Na4Co2O5 erfolgt graphisch.

Electronic Structure and Bonding in Tricoordinate Amido Complexes of Transition Metals

“…Three-coordinate metal centers are also present in a related family of binuclear M 2 L 4 complexes (M = Cr, Mn, Fe, Co, Ni) prepared in recent years, which bear amido terminal ligands and amido or phosphido bridges. ,− Other than these compounds in which the bulky ligands may give sterical protection to the metal center, thus favoring the coordinative unsaturation, some remarkable cases of bare three-coordinate compounds are known. These include the mononuclear [MN 3 ] 6- ions in Ca 6 MN 5 (M = Mn, Fe) and A 3 MN 3 families (A = alkaline earth; M = V, Cr, Mn, Fe), − some trihalides MX 3 (X = F, M = V, Cr, Fe; X = Cl, M = Ti, Fe; X = I, M = Ti) studied by electron diffraction in the gas phase, − and the mononuclear Hoppe anions [MO 3 ] n- (M = Fe, Co). − Tricoordinated metal atoms can also be found in the oxo-bridged binuclear [M 2 O 5 ] 6- (M = Fe − and Co , ) and in the tetranuclear [Co 4 O 9 ] 10- anions. Finally, edge-sharing tricoordinate transition metal atoms appear in the binuclear Hoppe anion [Co 2 O 4 ], - as well as in Cr 2 Cl 4 and Co 2 Br 4 , in which each metal atom is trigonally coordinated by bare oxide or halide anions.…”

“…These include the mononuclear [MN 3 ] 6ions in Ca 6 -MN 5 (M ) Mn, Fe) and A 3 MN 3 families (A ) alkaline earth; M ) V, Cr, Mn, Fe), 30-32 some trihalides MX 3 (X ) F, M ) V, Cr, Fe; X ) Cl, M ) Ti, Fe; X ) I, M ) Ti) studied by electron diffraction in the gas phase, [33][34][35] and the mononuclear Hoppe anions [MO 3 ] n-(M ) Fe, Co). [36][37][38] Tricoordinated metal atoms can also be found in the oxo-bridged binuclear [M 2 O 5 ] 6-(M ) Fe 39-42 and Co 43,44 ) and in the tetranuclear 45 [Co 4 O 9 ] 10-…”

On the Crystal Chemistry of Alkali Metal Oxocobaltates

“…The more recent work from Birx and Hoppe had the remarkable title "On the Knowledge of Disorder Phenomena in Oxides with the Motive of Butterfly, on Rb 2 K 4 [O 2 CoOCoO 2 ]" 70. “CoO“, which was obtained from Co(NO 3 ) 2 · 6H 2 O by precipitation from aqueous solution with NaHCO 3 and subsequent heating to 360 °C (36 h), was reacted.…”