New Silver(I) Coordination Polymer with Fe 4 Single-Molecule Magnets as Long Spacer

摘要

In continuation of our work on supramolecular architectures of single-molecule magnets (SMMs) as a promising strategy in developing their magnetic performance, in this paper we report the synthesis and single crystal X-ray structure of the centered triangular tetrairon(III) SMM, [Fe 4 (PhpPy) 2 (dpm) 6 ], Fe 4 (Hdpm = dipivaloylmethane, H 3 PhpPy = 2-(hydroxymethyl)-2-(4-(pyridine-4-yl)phenyl)propane-1,3-diol), and its assembly in the coordination polymer {[Fe 4 (PhpPy) 2 (dpm) 6 Ag](ClO 4 )} n , Fe 4 Ag , upon reaction with silver(I) perchlorate. Thanks to the presence of the pyridyl rings on the two tripodal ligands, Fe 4 behaves as divergent ditopic linker, and due to the Fe 4 :AgClO 4 1:1 ratio, Fe 4 Ag probably possesses a linear arrangement in which silver(I) ions are linearly coordinated by two nitrogen atoms, forming 1D chains whose positive charge is balanced by the perchlorate anions. The stabilization of such a polymeric structure can be ascribed to the long distance between the two donor nitrogen atoms (23.4 ?) and their donor power. Fe 4 Ag shows slow relaxation of the magnetization which follows a thermally activated process with U eff / k B = 11.17(18) K, τ 0 = 2.24(17) 10 ?7 s in zero field, and U eff / k B = 14.49(5) K, τ 0 = 3.88(8) 10 ?7 s in 1-kOe applied field, in line with what reported for tetrairon(III) SMMs acting as building blocks in polymeric structures.