Über Guanidinate von Europium und Ytterbium und Neues zu den Ytterbiumamiden

摘要

This work describes the ammonothermal synthesis, crystal structures and magnetism of the first guanidinates of europium and ytterbium. It presents the singly deprotonated guanidinates of Eu2+ and Yb3+, Eu(CN3H4)2 and Yb(CN3H4)3, as well as the doubly deprotonated guanidinates of Eu2+ and Yb2+, EuC(NH)3 and YbC(NH)3.Also, new results of the ytterbium amides are discussed, especially concerning their crystal structures and the magnetism of Yb(NH2)3. The singly deprotonated guanidinates show ionic interactions and hydrogen bonding.These competing forces can lead to complex crystal structures, changes in conformation of the guanidinate units and polymorphism, as studied here for Eu(CN3H4)2. Yb(CN3H4)3, however, forms an open structure related to the ReO3 type. The doubly deprotonated guanidinates EuC(NH)3 and YbC(NH)3 do not form hydrogen bonds and can be regarded as salts with a large anion. The magnetism of the studied compounds was considered to stem from low-dimensional structural fragments: isolated magnetic Yb3+ ions in Yb(CN3H4)3, ferromagnetic interactions along Eu2+ chains in alpha-Eu(CN3H4)2, and antiferromagnetically ordered layers of Yb3+ ions in Yb(NH2)3.