The Cluster Compounds Ag[W6Br14] and Ag2[W6Br14]
Abstract
enThe reaction of W6Br12 with AgBr in evacuated silica tubes (temperature gradient 925 K/915 K) yielded brownish black octahedra of Ag[W6Br14] (I) and yellowish green platelets of Ag2[W6Br14] (II) both in the low temperature zone. (I) crystallizes cubically (Pn3 (no. 201); a = 13.355 Å, Z = 4) and (II) monoclinically (P21/c (no. 14); a = 9.384 Å, b = 15.383 Å, c = 9.522 Å, β = 117.34°, Z = 2). Both crystal structures contain isolated cluster anions, namely [(W6Bri8)Bra6]1– and [(W6Bri8)Bra6])]2–, respectively, with the mean distances and angles: (I) d(W–W) = 2.648 Å, d(W–Bri) = 2.617 Å, d(W–Bra) = 2.575 Å, d(Bri…Bri) = 3.700 Å, d(Bri…Bra) = 3.692 Å, ∠W–Bri–W = 60.78°.
(II) d(W–W) = 2.633 Å, d(W–Bri) = 2.624 Å, d(W–Bra) = 2.613 Å, d(Bri…Bri) = 3.710 Å, d(Bri…Bra) = 3.707 Å, ∠W–Bri–W = 60.23°. The Ag+ cations are trigonal antiprismatically coordinated in (I) with d(Ag–Br) = 2.855 Å, but distorted trigonally planar in (II) with d(Ag–Br) = 2.588–2.672 Å. The structural details of hitherto known compounds with [W6Br14] anions will be discussed.
Abstract
deDie Clusterverbindungen Ag[W6Br14] und Ag2[W6Br14]
Bei der Umsetzung von W6Br12 mit AgBr in evakuierten Quarzglasampullen (Temperaturgradient 925 K/915 K) entstehen in der kalten Zone nebeneinander schwarzbraune Oktaeder von Ag[W6Br14] (I) und gelbgrüne Blättchen von Ag2[W6Br14] (II). (I) kristallisiert kubisch (Pn3 (Nr. 201); a = 13.355 Å, Z = 4) und (II) monoklin (P21/c (Nr. 14); a = 9.384 Å, b = 15.383 Å, c = 9.522 Å, β = 117.34°, Z = 2). Die Kristallstrukturen enthalten die isolierten Clusteranionen [(W6Bri8)Bra6]1– bzw. [(W6Bri8)Bra6])]2–, mit den mittleren Abständen und Winkeln: (I) d(W–W) = 2.648 Å, d(W–Bri) = 2.617 Å, d(W–Bra) = 2.575 Å, d(Bri…Bri) = 3.700 Å, d(Bri…Bra) = 3.692 Å, ∠W–Bri–W = 60.78°.
(II) d(W–W) = 2.633 Å, d(W–Bri) = 2.624 Å, d(W–Bra) = 2.613 Å, d(Bri…Bri) = 3.710 Å, d(Bri…Bra) = 3.707 Å, ∠W–Bri–W = 60.23°. Die Ag+-Kationen sind in (I) trigonal-antiprismatisch koordiniert mit d(Ag–Br) = 2.855 Å, in (II) verzerrt trigonal-planar mit d(Ag–Br) = 2.588–2.672 Å. Die strukturellen Einzelheiten der bisher bekannten Verbindungen mit [W6Br14]-Anionen werden diskutiert.
