Metal Flux Growth of Lanthanide Carbide Hydrides Using Anthracene.

Reactions of anthracene in Ln/T eutectic mixtures (Ln = La, Yb; T = Ni, Cu) have produced crystals of new complex lanthanide carbide hydride phases. The thermal decomposition of anthracene provides a source of both carbon and hydrogen. LaCH x forms in space group Pnma with unit cell parameters a = 7.2736(4) Å, b = 3.7218(2) Å, and c = 13.0727(7) Å. Yb 2 CH x forms in space group P -3 m 1 with unit cell parameters a = 3.5659(4) Å and c = 5.8000(8) Å, with a structure related to that of Ho 2 CF 2 . The presence of hydride in interstitial sites is supported by the formation of different compounds in the absence of hydrogen and by comparison to known hydride structures. 1 H nuclear magnetic resonance (NMR) spectra collected on LaCH x show two unique hydride resonances, in agreement with the two available interstitial sites. Density of states calculations show that filling the tetrahedral sites in LaCH x with hydrogen increases metallic behavior, while adding hydrogen into the tetrahedral sites in Yb 2 CH x induces the formation of a band gap.