Structural and Magnetic Properties of a {GdCu₅}₂ Metallacrown Dimer with a Disulfonate Linker

Abstract

The complex {Na2(H2O)8[GdCu5(GlyHA)5(H2O)4L]2}L2·2.5DMF ·10.5H2O (1, where GlyHA2‐ = glycinehydroxamate, L2‐ = 4,4'‐bis(2‐sulfonatostyryl)biphenyl) was obtained as the outcome of the metathesis reaction of previously reported [GdCu5(GlyHA)5(CO3)(NO3)(H2O)5]·3.5H2O with an excess of the disulfonate's sodium salt. X‐Ray analysis of 1 shows a dimeric structure in which 15‐metallacrown‐5 units {GdCu5}3+ are arranged in an “edge‐to‐edge” manner by way of two linking disulfonates, L2‐. Magnetic studies of polycrystalline 1 over a temperature range of 2 – 300 K revealed both Gd‐‐Cu ferromagnetic and Cu‐‐Cu antiferromagnetic interactions within the metallacrown unit. Experimental χMTvs. T data for 1 were fitted using different theoretical models. A two‐J model, which takes into account both exchange interactions between adjacent copper(II) ions and the Gd‐Cu exchange interactions allows fitting of the χMTvs. T data in the whole temperature range. The values obtained for the exchange parameters are in accord with previously reported parameters for Ln(III)‐Cu(II) 15‐metallacrowns‐5. The 240 GHz powder EPR spectra for 1 were recorded at between 30 and 150 K.