BaClSCN und Na4Mg(SCN)6: Zwei neue wasserfreie Thiocyanate der Erdalkalimetalle

Abstract

Frau Professor Marianne Baudler zum 80. Geburtstag gewidmet Inhaltsu È bersicht. Die Reaktion von BaCl 2 und NaSCN fu È hrte zu Einkristallen von BaClSCN (P 2 1 /m, Z = 2, a = 588,6(1) pm, b = 465,8(1) pm, c = 864,4(2) pm, b = 100,20(3)°, R all = 0,0214). Die Verbindung kristallisiert mit einer neuen Struktur, in der sich entlang [001] anionische Schichten von SCN ± und Cl ± abwechseln. Die SCN ± -Ionen koordinieren die Ba 2+ -Ionen sowohl u È ber die N-als auch u È ber die S-Atome. Auch Na 4 Mg(SCN) 6 (P 3 1c, Z = 2, a = 863,8(1) pm, c = 1399,3(2) pm, R all = 0,0870), dargestellt aus NaSCN und MgCl 2 , kristallisiert mit einer Schichtstruktur. Zwischen die Anionenschichten werden abwechselnd entweder Na + -Ionen oder Na + -Ionen und Mg 2+ -Ionen eingebaut. Betrachtet man nur die C-Atome der SCN ± -Ionen, so bilden diese eine hexagonal dichteste Kugelpackung, in der 5/6 aller Oktaederlu È cken durch Kationen besetzt sind.

Crystal structure of lead chloride thiocyanate, PbCl(SCN)

“…The position of the potential third cap is occupied by a chlorine atom, but the Pb-Cl distance, 3.72 Å, is too long to be considered. This environment is very similar to the one observed in BaCl(SCN) where the cation is located at the centre of a tricapped trigonal prism [1]. Among lead compounds, the present environment is not unusual: a mono-or a bicapped trigonal prismatic arrangement is observed in several chlorides or bromides as NH 4Pb2Cl5, NH4Pb2Br5 or [Co(NH3)6](Pb4Cl11) [2][3][4].…”

“…SCN -is a highly versatile ambidentate ligand with fifteen modes of coordination: two terminal modes and thirteen multidentate bridging modes, ranging from bi-to hexadentate [5]. The present pentadentate mode (Va in ref [5]) is rather rare, but has already been observed in BaCl(SCN) and Na 4Mg(SCN)6 [1]. The chlorine atoms are m3-coordinated under forming tetrahedra.…”

Ion transport mechanism in anhydrous lithium thiocyanate LiSCN Part I: ionic conductivity and defect chemistry

“…Apart from recently prepared tri-cationic cyanamides with the composition Li 2 MSn 2 (NCN) 6 (M = Mg 45 und Mn 46 ), anhydrous thiocyanates, nitrides or cyanides of lithium and any divalent transition metal are unknown so far, which makes the structure of Mg 1.02 Li 3.96 (SCN) 6 a hitherto unknown structure type (details in the ESI†). Mixed alkali and alkaline earth metal pseudo -halides are rare, 47–49 and even though Na 4 Mg(SCN) 6 has a very similar composition, its crystal structure is very different. The observation that the new phase Mg 1.02 Li 3.96 (SCN) 6 has a much higher conductivity than even highly doped Li(SCN) is related to the coordination polyhedra of Mg 2+ and Li + in this structure (ESI† Fig.…”

Crystal structure of lead chloride thiocyanate, PbCl(SCN)

“…The position of the potential third cap is occupied by a chlorine atom, but the Pb-CI distance, 3.72 A, is too long to be considered. This environment is very similar to the one observed in BaCl(SCN) where the cation is located at the centre of a tricapped trigonal prism [1]. Among lead compounds, the present environment is not unusual: a mono-or a bicapped trigonal prismatic arrangement is observed in several chlorides or bromides as NH4Fb2Cl 5 , NH4Pb2Br 5 or [Co(NH3)6](Pb4Clii) [2][3][4].…”