ISSN:
0044-2313
Keywords:
Tetrapnictidotitanate(IV)
;
centered heterocubanes
;
hierarchical derivative of Cr3Si and KGe
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Tetrapnictidotitanates(IV) M4TiX4 (M = Sr, Ba; X = P, As), hierarchical Derivatives of the KGe Structure K4□Ge4The four new tetrapnictidotitanates(IV) Sr4TiP4, Sr4TiAs4, Ba4TiP4 and Ba4TiAs4 are synthesized from the binary pnictides MX (M = Sr, Ba and X = P, As) and elementary titanium in tantalum ampoules. The compounds are isotypic and isoelectronic with Ba4SiAs4 (space group P43n (no. 218); cP72; Z = 8; Sr4TiP4: a = 1259.0(1) pm; Sr4TiAs4: a = 1288.3(4) pm; Ba4TiP4: a = 1316.6(2) pm; Ba4TiAs4: a = 1346.9(2) pm). The transition metal compounds form cubic, metallic reflecting crystals (Sr4TiP4 (green); Sr4TiAs4 (silver coloured); Ba4TiP4 (silver coloured); Ba4TiAs4 (violet). They are semiconducting and very sensitive against air and moisture. The structure is a hierarchical derivative of Cr3Si (A15) and KGe type: Cr6Si2 ≙ (□Ge4K4)6(□Ge4K4)2 ≙ (TiX4M4)6(TiX4M4)2, where Ti occupies the positions of the Cr3Si structure, and the alkaline-earth metal and pnicogen atoms occupy the positions of the KGe structure. Therefore, Ti is surrounded by four X and four more distant M atoms forming a heterocubane. The mean bond lengths are: d(Ti—P) = 238.0(5) pm; 307 ≤ d(Sr—P) ≤ 333 pm; d(Ti—As) = 245.9(4); 313 ≤ d(Sr—As) ≤ 341 pm; d(Ti—P) = 240.5(5); 324 ≤ d(Ba—P) ≤ 348 pm; d(Ti—As) = 248.3(3) pm; 331 ≤ d(Ba—As) ≤ 355 pm.
Notes:
Die vier neuen Tetrapnictidotitanate(IV) Sr4TiP4, Sr4TiAs4, Ba4TiP4 und Ba4TiAs4 wurden aus den binären Komponenten MX (M = Sr, Ba und X = P, As) und elementarem Titan in Tantalampullen dargestellt. Alle Verbindungen sind isotyp und isoelektronisch zu Ba4SiAs4 (Raumgruppe P43n (Nr. 218), cP72, Z = 8; Sr4TiP4: a = 1259.0(1) pm; Sr4TiAs4: a = 1288.3(4) pm; Ba4TiP4: a = 1316.6(2) pm; Ba4TiAs4: a = 1346.9(2) pm). Die Übergangsmetallverbindungen bilden würfelförmige, metallisch reflektierende Kristalle (Sr4TiP4 (grün), Sr4TiAs4 (silberfarben) Ba4TiP4 (silberfarben), Ba4TiAs4 (violett). Sie sind halbleitend und sehr empfindlich gegenüber Luft und Feuchtigkeit. Die Struktur ist eine hierarchische Variante vom Cr3Si- (A15) und KGe-Typ: Cr6Si2 ≙ (□Ge4K4)6(□Ge4K4)2 ≙ (TiX4M4)6(TiX4M4)2, in der die Ti-Atome die Positionen der Cr3Si-Struktur, die Erdalkalimetall- und Pnicogenatome die Positionen der KGe-Struktur besetzen. Ti ist deshalb von vier X-Atomen und von vier weiter entfernten M-Atomen in Form eines Heterokubans umgeben. Die mittleren Bindungslängen sind: d(Ti—P) = 238.0(5) pm, 307 ≤ d(Sr—P) ≤ 333 pm; d(T—As) = 245.9(4), 313 ≤ d(Sr—As) ≤ 341 pm; d(Ti—P) = 240.5(5), 324 ≤ d(Ba—P) ≤ 348 pm; d(Ti—As) = 248.3(3) pm, 331 ≤ d(Ba—As) ≤ 355 pm.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19966221112
Permalink
