Die Lanthanid(III)-ortho-Thiophosphate(V) vomTypM[PS4] (M= La–Nd, Sm, Gd–Er): Synthese, Kristallstruktur und 31P-NMR-Untersuchungen / The M[PS4]-Type Lanthanide(III) ortho-Thiophosphates(V) (M = La–Nd, Sm, Gd–Er): Synthesis, Crystal Structure, and 31P NMR Investigations