Synthesis, Structure, and Thermoelastic Properties of LiSn2Br3(CN2) and Sn4Br2(CN2)3

• Published in: European journal of inorganic chemistry Vol. 2021; no. 44; pp. 4572 - 4578
• Main Authors: Löber, Manuel, Ströbele, Markus, Romao, Carl P., Meyer, Hans‐Jürgen
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 25.11.2021
• Subjects: Carbodiimide; Carbodiimides; Crystal structure; DFPT; Differential thermal analysis; DTA; Halides; Inorganic chemistry; Lithium; Metathesis; Perturbation theory; Solid-State Reaction; Thermal expansion; Thermoelastic properties; Tin
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202100660

Tin carbodiimides have been reported with various compositions, prepared via solid‐state metathesis reactions by heating tin halides and lithium carbodiimide at moderate temperatures. The formations of two new compounds, LiSn2Br3(CN2) and Sn4Br2(CN2)3 are monitored by differential thermal analysis (DTA), and crystal structures are reported as refined on basis of X‐ray diffraction studies. The structure of LiSn2Br3(CN2) can be described by two interpenetrating frameworks of corner‐linked coordination polyhedra, raising the possibility of negative thermal expansion (NTE) as investigated by density functional perturbation theory (DFPT). Like some previously reported tin carbodiimide compounds, LiSn2Br3(CN2) was also found to be a semiconductor with an indirect band gap of 2.5 eV, as determined by DFT calculations. Two tin bromide carbodiimide compounds LiSn2Br3(CN2) and Sn4Br2(CN2)3 were synthesized via solid‐state metathesis reactions. The structures were determined by single‐crystal X‐ray diffraction and found to be isotypic to some already known compounds. DTA studies reveal, that LiSn2Br3(CN2) is formed as early as 150 °C and transforms later into Sn4Br2(CN2)3. DFPT calculations indicated negative thermal expansion of LiSn2Br3(CN2) at low temperatures.