New Silver(I) Coordination Polymer with Fe₄ Single-Molecule Magnets as Long Spacer

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, [Fe₄(PhpPy)₂(dpm)₆], Fe₄ (Hdpm = dipivaloylmethane, H₃PhpPy = 2-(hydroxymethyl)-2-(4-(pyridine-4-yl)phenyl)propane-1,3-diol), and its assembly in the coordination polymer {[Fe₄(PhpPy)₂(dpm)₆Ag](ClO₄)}_n, Fe₄Ag, upon reaction with silver(I) perchlorate. Thanks to the presence of the pyridyl rings on the two tripodal ligands, Fe₄ behaves as divergent ditopic linker, and due to the Fe₄:AgClO₄ 1:1 ratio, Fe₄Ag 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 Å) and their donor power. Fe₄Ag shows slow relaxation of the magnetization which follows a thermally activated process with U_eff/k_B = 11.17(18) K, τ₀ = 2.24(17) 10⁻⁷ s in zero field, and U_eff/k_B = 14.49(5) K, τ₀ = 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. View Full-Text