Wide Compositional and Structural Diversity in the System Tl/Bi/P/Q (Q = S, Se) and Observation of Vicinal P−Tl J Coupling in the Solid State

• Published in: Inorganic chemistry 2007-04, Vol.46 (9), p.3632-3644
• Main Authors: Gave, Matthew A, Malliakas, Christos D, Weliky, David P, Kanatzidis, Mercouri G
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic062465h

The compounds α-TlBiP2Se6 (I), β-TlBiP2Se6 (II), TlBiP2S6 (III), Tl3Bi3(PS4)4 (IV), TlBiP2S7 (V), and Tl3Bi(PS4)2 (VI) were synthesized, and the structures of I−V were determined by single-crystal X-ray diffraction analysis. The structure of I features infinite chains. Those of compounds II, III, and V are layered. The structure of IV features a three-dimensional framework. Tl4Bi2(PS4)2(P2S6) (VII) was also prepared for comparison to the title compounds. The band gaps of each compound are 1.23, 1.27, 1.81, 1.88, 2.06, 1.98, and 1.97 eV for I−VII, respectively. Compounds I, III, IV, and VI melt congruently at 544, 595, 495, and 563 °C, respectively, and compounds II, V, and VII melt incongruently at 544, 509, and 600 °C, respectively. Solid-state 31P NMR spectroscopy of the reported compounds demonstrates chemical shifts and chemical shift anisotropies in line with related chalcophosphate materials. Evidence for two-bond P−Tl J coupling was observed in 31P NMR spectra (J = 481−1781 Hz), and to the best of our knowledge, this is the first example of two-bond P−Tl J coupling and the first example of P−Tl coupling in the solid state. It was possible to assign chemical shifts of inequivalent 31P atoms from the same [P x Q y ] z - anion type based on different modes of metal ion coordination to the chalcogen. These assignments provide information about the vicinal metal ion contribution to the 31P chemical shift.