In Situ X-ray Diffraction Study of the Thermal Decomposition of Selenogallates Cs₂[Ga₂(Se₂)_2–xSe_2+x] (x = 0, 1, 2)

Abstract

The selenogallates CsGaSe and CsGaSe release gaseous selenium upon heating. An in situ high-temperature X-ray powder diffraction analysis revealed a two-step degradation process from CsGaSe to CsGaSe and finally to CsGaSe. During each step, one Se unit of the anionic chains in Cs[Ga(Se)Se] ( x = 0, 1, 2) decomposes, and one equivalent of selenium is released. This thermal decomposition can be reverted by simple addition of elemental selenium and subsequent annealing of the samples below the decomposition temperature. The influence of the diselenide units in the anionic selenogallate chains on the optical properties and electronic structures was further studied by UV/vis diffuse reflectance spectroscopy and relativistic density functional theory calculations, revealing increasing optical band gaps with decreasing Se content.

Homoleptic Group 13 Trimethylsilylchalcogenolato Metalates [M(ESiMe3)4]− (M = Ga, In; E = S, Se): Metastable Precursors for Low-Temperature Syntheses of Chalcogenide-Based Materials

“…The residue obtained by thermolysis of Ph 4 P­[In­(SSiMe 3 ) 4 ] ( 3 ) has not yet been fully characterized. We do not have any evidence that after desilylation a coordination polymer with edge-bridged tetrahedral [InS 2 ] − anions in a SiS 2 -like polymeric strand, as observed for Cs­[GaSe 2 ], or a 2D arrangement of corner-connected heteroadamantane subunits with bridging chalcogen atoms, as observed for Tl­[MSe 2 ] (M = Ga, In), is formed. Instead, NMR spectra suggest a thermal dissociation of Ph 4 P­[In­(SSiMe 3 ) 4 ] into Ph 4 P­[SSiMe 3 ] and [In­(SSiMe 3 ) 3 ], which spontaneously eliminates S­(SiMe 3 ) 2 to form the oligomer [In­(S)­(SSiMe 3 )] n (see the Supporting Information).…”

“…Calcd for C 48 H 136 Cu 2 Ga 2 P 8 S 8 Si 8 : C, 33.73; H, 8.02, S, 15.01. Found: C, 33.15; H, 7.89; S, 13 45…”

Fluorotrithiophosphate Abstraction from the Difluoropentathiodiphosphate Dianion: d8 and d6 Complexes of [η2-S3PF]2–

“…Generally, prior thiophosphate complexes are often synthesized with solid-state chemistry methods such as vacuum sealed tubes , or by flux growth methods. , The metal-dependent variety of different coordination motifs leads to the formation of chains, layers, or 3D networks. Similar complexes of selenophosphates are known, albeit not as common. − Thiophosphates and selenophosphates salts have been used in a variety of applications, including nonlinear optics, − electrolytes in batteries, − or (as their complexes) as magnetic materials. , …”

Mechanistic insight of KBiQ2 (Q = S, Se) using panoramic synthesis towards synthesis-by-design

“…13 With reaction types and assembly rules, predictive power of material synthesis can be achieved, leading to intentional synthesis of targeted materials with chosen, desired properties. 25 In-situ powder X-ray diffraction has been utilized for various interests such as materials discovery 18,19,26 and mechanism elucidation 25,[27][28][29][30][31][32][33] , as well as the investigation of metathesis reactions 27,34 , self-propagating high temperature syntheses 14,25,28 , phase change 14,35 , decomposition 36 , and crystallization 14,25,28 . This approach has shown success in discovering new materials, even in systems that were previously investigated.…”

“…In situ powder X-ray diffraction has been utilized for various interests such as materials discovery 18,19,26 and mechanism elucidation, 25,27–33 as well as the investigation of metathesis reactions, 27,34 self-propagating high temperature syntheses, 14,25,28 phase change, 14,35 decomposition, 36 and crystallization. 14,25,28 This approach has shown success in discovering new materials, even in systems that were previously investigated.…”