Eine Antiperowskitstruktur bei ternären Tetrathiafulvalen-Salzen: Aufbau, Verzerrung und antiferromagnetische Ordnung

A Three-Dimensional M3 AB-Type Hybrid Organic-Inorganic Antiperovskite Ferroelectric: [C3 H7 FN]3 [SnCl6 ]Cl

Since the first perovskite CaTiO₃ was discovered in 1839, the development of perovskite has a history of 180 years. The emergence of solar cells (CH₃ NH₃ )PbI₃ has set off the trend of hybrid organic-inorganic perovskite (HOIP) materials. Since then, various HOIPs have sprung up and been widely used in various material devices. Among them, HOIP ferroelectrics have gained widespread attention. However, antiperovskite, as a twin brother of perovskite, has been neglected although it has similar structure with perovskite. Here, we successfully found that [C₃ H₇ FN]₃ [SnCl₆ ]Cl has a three-dimensional (3D) antiperovskite structure with the formula M₃ AB. Importantly, the compound exhibits obvious ferroelectric properties with an Aizu notation of 622F6 at 391 K. To the best of our knowledge, this is the first 3D hybrid organic-inorganic antiperovskite ferroelectric, which will greatly promote the development of antiperovskite families with more superior physical properties.

Hybrid Organic-Inorganic Antiperovskites

Substitution of A-site and/or X-site ions of ABX₃ -type perovskites with organic groups can give rise to hybrid perovskites, many of which display intriguing properties beyond their parent compounds. However, this method cannot be extended effectively to hybrid antiperovskites. Now, the design of hybrid antiperovskites under the guidance of the concept of Goldschmidt's tolerance factor is presented. Spherical anions were chosen for the A and B sites and spherical organic cations for the X site, and seven hybrid antiperovskites were obtained, including (F₃ (H₂ O)_x )(AlF₆ )(H₂ dabco)₃ , ((Co(CN)₆ )(H₂ O)₅ )(MF₆ )(H₂ dabco)₃ (M=Al³⁺ , Cr³⁺ , or In³⁺ ), (Co(CN)₆ )(MF₆ )(H₂ pip)₃ (M=Al³⁺ or Cr³⁺ ), and (SbI₆ )(AlF₆ )(H₂ dabco)₃ . These new structures reveal that all ions at A, B, and X sites of inorganic antiperovskites can be replaced by molecular ions to form hybrid antiperovskites. This work will lead to the synthesis of a large family of hybrid antiperovskites.

Strong Magnetic Interactions through Weak Bonding Interactions in Organometallic Radicals: Combined Experimental and Theoretical Study

The magnetic properties of a series of three neutral radical organometallic complexes of general formula [CpNi(dithiolene)]. have been investigated by a combination of X-ray crystal structure analysis and magnetic susceptibility measurements, while the assignment of the exchange coupling constants to the possible exchange pathways has been accomplished with the help of calculations based on density functional theory (DFT). The syntheses and X-ray structures of [CpNi(adt)] (adt=acrylonitrile-2,3-dithiolate) and [CpNi(tfd)] (tfd=1,2-bis(trifluoromethyl)ethene-1,2-dithiolate) complexes are described, while [CpNi(mnt)] (mnt=maleonitriledithiolate) was reported earlier. In the three complexes, we observed strong antiferromagnetic coupling that could not be explained solely by short SS intermolecular contacts. Our calculations indicated that spin density in these complexes is strongly delocalized on the NiS2 moiety, with up to 20% on the Cp ring. As a consequence, CpCp and Cpdithiolene overlap interactions have been identified as responsible for antiferromagnetic couplings. The [CpNi(adt)] complex thus has a value J=-369.5 cm(-1) for an exchange interaction through a pi stacking due to the CpCp overlap.