Metal Flux Growth of Lanthanide Carbide Hydrides Using Anthracene

Decompositionof anthracene in metal flux reactions providesa source of carbon and hydrogen interstitials to products formingin the melt. Anthracene was reacted with fluxes comprised of La/Niand Yb/Cu eutectic melts to make two new rare earth carbide hydrides.Possible hydride sites were identified from single-crystal X-ray diffractionstudies, and the presence of hydrogen in LaCH (x) was confirmed by H-1 MAS-NMR. Reactions of anthracene in Ln/T eutectic mixtures (Ln= La, Yb;T = Ni, Cu) have produced crystals of new complex lanthanide carbidehydride phases. The thermal decomposition of anthracene provides asource of both carbon and hydrogen. LaCH (x) forms in space group Pnma withunit cell parameters a = 7.2736(4) & ANGS;, b = 3.7218(2) & ANGS;, and c = 13.0727(7)& ANGS;. Yb2CH (x) forms in spacegroup P-3m1 with unit cell parameters a = 3.5659(4) & ANGS; and c = 5.8000(8)& ANGS;, with a structure related to that of Ho2CF2. The presence of hydride in interstitial sites is supported by theformation of different compounds in the absence of hydrogen and bycomparison to known hydride structures. H-1 nuclear magneticresonance (NMR) spectra collected on LaCH (x) show two unique hydride resonances, in agreement with the two availableinterstitial sites. Density of states calculations show that fillingthe tetrahedral sites in LaCH (x) with hydrogenincreases metallic behavior, while adding hydrogen into the tetrahedralsites in Yb2CH (x) induces theformation of a band gap.

Automated summary

Anthracene decomposition in metal flux reactions provides carbon and hydrogen interstitials for product formation. Reactions of anthracene with La/Ni and Yb/Cu fluxes produced new rare earth carbide hydrides. The presence of hydrogen in LaCH (x) was confirmed by H-1 MAS-NMR, and possible hydride sites were identified through X-ray diffraction studies. Anthracene reactions in Ln/T eutectic mixtures (Ln = La, Yb; T = Ni, Cu) resulted in the formation of complex lanthanide carbide hydride phases.