Synthesis and Structures of Two Thiocyanato-Lanthanoid Cages

Abstract  

The cages {La₂(NCS)₅(NCMe)₆}₂O]·MeCN and {Eu₂(NCS)₅(NCMe)₅}₂O]·MeCN have been prepared by redox transmetallation between the lanthanoid metals and mercuric thiocyanate in acetonitrile. The structure of the former has a core of four La atoms bonded to a central oxygen atom. Two La atoms are nine coordinate being bonded to oxygen, four terminal MeCN ligands and four N-bridged thiocyanato ligands, whereas the other two are eight coordinate being bonded to oxygen, the four bridging thiocyanato ligands, two terminal acetonitrile molecules, and a terminal N-bonded thiocyanate ion. In the Eu complex, there is a similar core of four Ln atoms bound to a central oxygen atom, but all Eu atoms are eight coordinate, and have four N-bridged thiocyanate ligands. Two have three MeCN ligands, whilst the other two have one terminal NCS⁻ and two acetonitrile ligands.