Low‐Temperature Oxidation of Ytterbium with Pyrrole in Liquid Ammonia. Formation of the First Unsubstituted Pyrrolates of a Rare Earth Element

The compounds [Yb2(Pyr)2(NH3)8][Yb(Pyr)5(NH3)] (1), [Yb(Pyr)3(PyrH)2(NH3)2] (2) and [Yb5(Pyr)12(NH3)4(NH2)]·2PyrH (3), (Pyr = pyrrolate anion, C4H4N‐; PyrH = pyrrole, C4H4NH) were obtained by the low‐temperature oxidation of ytterbium with the amine pyrrole in liquid ammonia. Single crystals of all three phases are formed next to each other, their yield depending on the temperature gradient of a subsequent thermal process in sealed glass ampoules. 1, 2 and 3 are the first unsubstituted pyrrolates of a rare earth element and display the decisive role of ammonia and the reaction conditions. The low temperature oxidation avoids polymerisation of the amine pyrrole. The crystal structures of 1, 2 and 3 exhibit units of different extension, different coordination spheres and oxidation states of ytterbium. The products were investigated by X‐ray single crystal diffraction, Mid IR and Far IR spectroscopy.