epsilon-caprolactam as a donor ligand for lanthanide halides: Formation ofcationic [Ln(C6H11NO)(6)Cl](2+) and [Ln(C6H11NO)(4)Cl-2](+) complexes

Examination of the coordination chemistry of epsilon -caprolactam with lant hanide trichlorides reveals that cationic epsilon -caprolactam-solvated com plexes of two types can be obtained from acetonitrile depending on the size of the metal. The larger lanthanides Ce, Nd, Pr, and Sm form capped octahe dral dications, [Ln(C6H11NO)(6)Cl](+2), with the chloride ligand in the cap ping position. The smaller metals Eu, Gd, and Ho form trans-octahedral mono cations [Ln(C6H11NO)(6)Cl](+2). Chloride ions are the counteranions in both cases.