Ligandenfeld‐ und ESR‐spektroskopische Untersuchungen zum JAHN‐TELLER‐Effekt des Ag²⁺‐Ions in fluoridischer Koordination

Abstract

Die Ligandenfeld‐ und ESR‐Spektren der extrem feuchtigkeitsempfindlichen Verbindungen AgMeIVF6 (MeIV :Sn, Zr) [I], A 2IAgF4 (AI:Rb, Cs) [II] und EIIAgF4 (EII:Sr, Ba) [III] wurden im Temperaturbereich zwischen 4 und 298°K aufgenommen. Danach enthalten die Fluoride [I] mit bisher unbekannten Strukturen schwach bis mäßig tetragonal geweitete AgF6‐Oktaeder in ferrodistortiver Ordnung, die Verbindungen [II] AgF6‐Oktaeder mit starker tetragonaler Weitung in antiferrodistortiver Ordnung, während im Falle der Fluoride [III] die für die KBrF4‐Struktur charakteristischen AgF4‐Planquadrate in antiferrodistortiver Ordnung bestätigt werden konnten. Die gefundenen ESR‐spektroskopischen Kovalenzfaktoren weisen für die Ag2+F−‐Bindung eine stärkere d‐Elektronendelokalisation und eine ausgeprägtere π‐Anisotropie aus als für die Cu2+F−‐Bindung.

Real and Hypothetical Intermediate-Valence AgII/AgIII and AgII/AgI Fluoride Systems as Potential Superconductors

“…The strongly elongated octahedral coordination of the Ag centers in Cs 2 AgF 4 (and Rb 2 AgF 4 ) deduced from ESR spectra [73] does not agree with structural data for Cs 2 AgF 4 . [69] Herein we have preferred the crystallographic structure of Cs 2 AgF 4 over the ESR data.…”

“…This compound has a structure similar to perovskite-related K 2 NiF 4 ; the only difference is in the compressed (and not elongated) octahedral environment around the metal center. [73] There are two equal AgÀF(1) bonds in the structure of Cs 2 AgF 4 (compare to CsAgF 3 with two different AgÀF(1) bonds). The DOS of this compound (shown in Figure 27 a ± d) in the À 8.1 to À 2.8 eV range is composed of states having mixed Ag(d) and F(p) character, as in CsAgF 3 .…”

The first example of a mixed valence ternary compound of silver with random distribution of Ag(i) and Ag(ii) cations

“…2). 34 The absolute values of the g tensor components are larger than the corresponding values for AgZrF 6 (g k = 2.58, g ⊥ = 2.11) and AgSnF 6 (g k = 2.65, g ⊥ = 2.12) 66 in agreement with the weaker ligand field 66,69 exerted by weakly coordinating SbF 6 − anions than those of the more electron-rich MF 6 −2 ones (M = Zr, Sn).…”

“…[66][67][68][69] Here we have studied the electronic spectra for the samples of Ag 3 (SbF 6 ) 4 , and two reference samples (Ag(SbF 6 ) 2 and AgSbF 6 ) in the NUV-vis-NIR range (5-50k cm −1 or ca. 0.6-6.2 eV).…”

[Ag(OH2)2][Ag(SO4)2]: A Hydrate of a Silver(II) Salt

“…Electronic spectra,i nc onjunction with the ESR spectra and quantum mechanical calculations, have proveni nt he past to be very useful for analysiso fc hemical bondingi nt he silver(II) systems. [25][26][27][28] Here we have studied the electronic spectra for the sample of AgSO 4 ·H 2 O, and reference AgSO 4 in the NUV/Vis-NIR range (300-1200 nm or ca. 1.0-4.1 eV).…”