Mono- and Dinuclear Macrocyclic Calcium Complexes as Platforms for Mixed-Metal Complexes and Clusters

Mono- and dinuclear calcium complexes of the Schiff-base macrocycles H4L have been prepared and characterized spectroscopically and crystallographically. In the formation of Ca(THF)(2)(H2L1), Ca-2(THF)(2)(mu-THF)(L-1), and Ca-2(THF)(4)(L-2), the ligand framework adopts a bowl-shaped conformation instead of the conventional wedge, Pacman-shaped structure as seen with the anthracenyl-hinged complex Ca-2(py)(5)(L-3). The mononuclear calcium complex Ca(THF)(2)(H2L1) reacts with various equivalents of LiN(SiMe3)(2) to form calcium/alkali metal clusters and dinuclear transition metal complexes when reacted subsequently with transition metal salts. The dinuclear calcium complex Ca-2(THF)(2)(mu- THF)(L-1), when reacted with various equivalents of NaOH, is shown to act as a platform for the formation of calcium/alkali metal hydroxide clusters, displaying alternate wedged and bowl-shaped conformations.