Syntheses and characterization of four heterometallic Ln-Co or Ln-Ni heptanuclear clusters with glycine as ligand

The self-assemble of Ln(ClO4)3 (Ln=Pr, Gd), M(ClO4)2 (M=Co, Ni) and glycine provides four new heptanuclear clusters {LnM6} and two of them were successfully characterized by X-ray structural analyses. Na[PrCo6(Gly)12](ClO4)4(H2O)6 (1) (Gly=NH2CH2COO−) crystallizes in the rhombohedral R-3c space group (a=b=12.4998(1) Å, c=62.4276(9) Å, and Z=6). The structure of the cation may be described as a Pr3+ ion situates in the center of an octahedral cage formed by six Co2+ atoms. Na[GdNi6(Gly)6(HGly)2(μ3-OH)3(μ2-OH2)(H2O)6]·(ClO4)7·(H2O)9 (2) attributes to the triclinic P-1 space group (a=13.3868(2) Å, b=15.2182(3) Å, c=19.2877(1) Å, α=86.73(0)°, β=80.430(1)°, γ=65.033(1)° and Z=2). The structure of the cation may be described as a Gd3+ ion is in the center of a prism formed by six nickel atoms. Primary structure analyses of Na4[PrCo6(Gly)9(μ3-OH)3(H2O)6]·(ClO4)7 (3) and Na4[GdNi6(Gly)9(μ3-OH)3(H2O)6]·(ClO4)7 (4) show they also have [LnM6(Gly)6(μ3-OH)3(H2O)6]6+ cores. 1 and 3 represent the first successfully attempt to syntheses of heptanuclear Ln-Co clusters. The magnetic measurement reveals that 2 exhibits ferromagnetic interaction.