11/15/17 Complexes as Molecular Models for Metal Halide Double Perovskite Materials

Abstract

Thirteen neutral complexes [E x M y X z -(PPh 3 ) n (L) m ] (E = Bi, Sb; M = Cu, Ag; X = Cl, Br, I; L = solvent) featuring three different motifs were prepared and characterized regarding their structure, stability, and absorption spectra. While not identical in structural motif, the compounds can serve as models for the influence of the composition E/M/X on the optical properties of double perovskites A 2 EMX 6 (A = Cs, CH 3 NH 3 ).

[SMe3]2[Bi2Ag2I10], a silver iodido bismuthate with an unusually small band gap

“…These compounds feature optical band gaps between 1.93 eV and 2.29 eV. 14,15,[23][24][25] Fig. 1 gives an overview of their structural motifs.…”

“…11,12 As the trends for other halogenido plumbates and bismuthates show, the band gap should narrow with the transition from chlorido and bromido to iodido compounds. 13–15 Unfortunately though, the corresponding Cs 2 BiAgI 6 proved to be unstable and so far could only be synthesized in nanocrystalline form. 16 Instead the related compound Cu 2 BiAgI 6 could recently be obtained.…”

Dibismuthates as Linking Units for Bis-Zwitterions and Coordination Polymers

“…Alternatively, other Lewis bases may play the role of electron-pair donors instead of these two halide ions; however, these [Bi 2 X 8 L 2 ] 2– species are less common than the all-halide dibismuthates [Bi 2 X 10 ] 4– . The lion’s share of the [Bi 2 X 8 L 2 ] 2– structures has been reported with solvent molecules (e.g., L = THF, 20 , 23 − 26 H 2 O, 27 DMSO, 26 , 28 − 32 acetone 28 , 33 , 34 ) coordinating to the bismuth centers (see Figure 1 ), but in some cases more sophisticated donor molecules such as bipyridines 35 − 42 can act as Lewis bases. On the basis of our CCDC search, the most common donor atom is oxygen, 20 , 23 − 34 , 38 , 42 − 44 followed by nitrogen, 35 − 37 , 39 − 41 and to our knowledge there is only one example with sulfur (dimethyl sulfide 45 ).…”

Copper- and Silver-Containing Heterometallic Iodobismuthates: Features of Thermochromic Behavior

“…Amongst the wide variety in the studied materials, prepared through various approaches, one promising method for altering electronic properties and developing new materials should be particularly emphasized: the combination of p - and d -elements ( d -elements typically being copper and silver) in the anion. According to this strategy, heterometallic copper- and silver-containing iodobismuthates with zero-dimensional [ 19 , 20 , 21 , 22 , 23 , 24 ], one-dimensional [ 20 , 25 , 26 , 27 , 28 ] ( Figure S1 ) or two-dimensional [ 29 , 30 ] anionic motifs have been characterized previously. However, the overall number of known heterometallic iodometallates remains lower than that of homometallic ones, but this trend can change, as recent works clearly demonstrate [ 27 , 31 , 32 , 33 , 34 ].…”