Mono- and Disamarium Azacryptand Complexes: A Platform for Cooperative Rare-Earth Metal Chemistry

Abstract

Mono- (H3LSm) and disamarium complexes (LSm2) were prepared by reaction of the azacryptand N[(CH2)2NHCH2-p-C6H4CH2NH(CH2)2]3N (H6L) with 1 or 2 equiv of Sm[N(SiMe3)2]3, respectively. The disamarium complex features free coordination sites on both metal centers available for bridging ligands shielded by phenylenes from tetrahydrofuran (THF) coordination. The reaction of LSm2 with KCN and 18-crown-6 yielded the adduct [LSm2-μ-η1:η1-CN][K(18-crown-6)(THF)2] featuring a bridging cyanide. The complexes were characterized by crystallography, electrochemical analysis, NMR, and optical spectroscopy, and the effective magnetic moments were determined via the Evans method.