Beiträge zur Chemie der Elemente Niob und Tantal. LXIX K₄Nb₆Cl₁₈ Darstellung, Eigenschaften und Struktur

Abstract

K4Nb6Cl18 läßt sich in kristalliner Form durch Erhitzen von Nb6Cl14 mit KCl oder einfacher aus KCl, Nb3Cl8 und Nb darstellen. Die Verbindung wird durch ihr chemisches, thermisches und optisches Verhalten charakterisiert. K4Nb6Cl18 kristallisiert monoklin in der Raumgruppe C 32h—C 2/m (a0 = 9,97; b0 = 16,51; c0 = 9,47 Å β = 115°). Die Struktur wurde durch optische Nachbildung der FOURIER. Transformierten und rechnerisch ausgeführte Verfeinerung bestimmt. Neuartig ist das Auftreten des anionischen Komplexes {[Nb6Cl12]Cl6}4−. Die darin enthaltene oktaedrische Nb6−=Gruppe ist regulär (dNb−Nb = 2,915Å K4Nb6Cl18) zeigt schwachen, von der Temperatur unabhängigen Paramagnetismus.

The New Niobium Cluster Azides (NH4)4[Nb6Cl12(N3)6](H2O)2 and Na1.15(3)La0.85(3)[Nb6Cl12(N3)6](H2O)13(1). Syntheses and Crystal Structure Determination

“…Nb 6 Cl 14 was used as starting material. This compound was synthesized by reacting Nb 3 Cl 8 with Nb foil 0932-0776 / 10 / 0500-0543 $ 06.00 c 2010 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com at 840 • C [6].…”

“…This compound was synthesized by reacting Nb 3 Cl 8 with Nb foil 0932-0776 / 10 / 0500-0543 $ 06.00 c 2010 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com at 840 • C [6]. In a typical reaction, 0.15 mmol (160 mg) fine-powdered Nb 6 Cl 14 was dissolved under stirring in approximately 10 mL H 2 O at 70 • C, and 1 mmol (65 mg) NaN 3 was added. The color of the solution changed from deep olive-green to deep olive-brown.…”

“…Niobium cluster compounds such as Nb 6 Cl 14 [1] can be dissolved in water or similar polar solvents yielding deep olive-green solutions containing solvated [Nb 6 Cl 12 ] 2+ ions [2]. This property makes this cluster ion an easy-to-use building block for reactions with water-soluble salts in aequeous solutions.…”

“…This property makes this cluster ion an easy-to-use building block for reactions with water-soluble salts in aequeous solutions. Frequently used salts are ionic azide compounds which form [Nb 6 Cl 12 (N 3 ) 6 ] 4− ions with the azides being attached to the terminal sites of the cluster. This reaction is accompanied by a color change of the solution to a deep olive-brown.…”

“…So far only the alkali metals K + [3], Rb + and Cs + [4] and the alkaline earth metals Ca 2+ , Sr 2+ and Ba 2+ [5] have been found to form well-crystallizing compounds. We report here the syntheses and the structure determination of (NH 4 ) 4 [Nb 6 Cl 12 (N 3 ) 6 ](H 2 O) 2 and of Na 1.15(3) La 0.85 (3) [Nb 6 Cl 12 (N 3 ) 6 ](H 2 O) 13 (1) .…”