Syntheses and crystal structures of a series of heptanuclear trigonal prismatic clusters {LnCu 6} (Ln=La, Sm, Er) with glycine and imidazole as ligands

Abstract

Three new heptanuclear trigonal prismatic polyhedra, [LnCu 6(μ 3-OH) 3(Gly) 6im 6](ClO 4) 6 (Ln=La ( 1), Sm ( 2), Er ( 3)) were synthesized through the self-assembly of Ln 3+, Cu 2+, glycine and imidazole in aqueous solution and characterized by X-ray structure analysis. The complexes crystallize in the rhombohedral R3 space group ( a= b=15.9194(5) Å, c=23.6190(14) Å, V=5183.8(4) Å 3, Z=3 ( 1); a= b=15.8824(3) Å, c=23.4244(5) Å, V=5117.19(17) Å 3, Z=3 ( 2); a= b=15.8774(3) Å, c=23.3428(5) Å, V=5096.15(17) Å 3, Z=3 ( 3)). In the cluster, Ln 3+ ion is situated in the center of a prism formed by six copper atoms and coordinates to nine oxygen atoms with a tricapped trigonal prismatic coordination polyhedron. Six glycinato ligands (each adopts a η 4-coordination mode and coordinates to two Cu 2+ and one Ln 3+ ions) and six imidazole terminal ligands (each coordinates to one Cu 2+) were used in the construction of the cluster.