Solid state and solution structures of the lanthanide complexes with cryptand (2.2.1): Crystallographic and NMR studies of a dimeric praseodymium (2.2.1) cryptate containing two μ-hydroxo bridges

A dimeric lanthanide cryptate was obtained by the addition of an excess of cryptand (2.2.1) to a slightly hydrated solution of the monomeric praseodymium (2.2.1) perchlorate complex in acetonitrile. This new lanthanide compound is centrosymmetric and displays the space groupP2₁/n. The encryptated metal ions are nine-coordinated, they are bonded to all the heteroatoms of a (2.2.1) ligand and they are linked to each other by two -hydroxo bridges. The hydroxyl groups are relegating the cryptands to both end of the dimer and the praseodymium ions are less effectively accomodated in the macrocylic internal cavities than in the case of the monomeric Pr(2.2.1) complex. The formation of both the monomeric and the dimeric lanthanide complexes is readily observed by proton NMR.Supplementary data relevant to this article are deposited with the British Library Lending Division as Supplementary Publication No. 82050 (24 pages).Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986.