A Mn-III triplesalen-based 1D pearl necklace: exchange interactions and zero-field splittings in a C-3-symmetric Mn-6(III) complex

作者：Glaser Thorsten^*; Heidemeier Maik; Theil Hubert; Stammler Anja; Boegge Hartmut; Schnack Juergen

来源：Dalton Transactions, 2010, 39(1): 192-199.

DOI：10.1039/b912593k

The reaction of the tert-butyl-substituted triplesalen ligand H(6)talen(t-Bu2) with 2.8 equivalents of Mn(OAc)(2)center dot 4H(2)O in MeOH in the presence of NaBPh4 results in the formation of the one-dimensional (1D) coordination polymer {[{(talen(t-Bu2))Mn-3(MeOH)}(2)(mu(2)-OAc)(3)](mu(2)-OAc)}(n)(BPh4)(2n) ({[Mn-6(III)](OAc)}(n)(BPh4)(2n)) which has been characterized by FTIR, elemental analysis, ESI-MS, single-crystal X-ray diffraction and magnetic measurements. The triplesalen ligand (talen(t-Bu2))(6-) provides three salen-like coordination compartments bridged in a meta-phenylene arrangement by a phloroglucinol backbone resulting in the trinuclear Mn-III base unit {(talen(t-Bu2))Mn-3}(3+). Two of these base units are bridged by three inner acetate ligands giving rise to the hexanuclear complex [{(talen(t-Bu2))Mn-3(MeOH)}(2)(mu(2)-OAc)(3)](3+) ([Mn-6(III)](3+)). These complexes are bridged by a single external acetate to form a 1D chain as pearls in a pearl necklace. Variable temperature-variable field and mu(eff) vs. T magnetic data have been analyzed in detail by full-matrix diagonalization of the appropriate spin-Hamiltonian consisting of isotropic exchange, zero-field splitting, and Zeeman interaction taking into account the relative orientation of the D-tensors. Satisfactory reproduction of the experimental data have been obtained for parameters sets J(1) = -(0.60 +/- 0.15) cm(-1), J(2) = -(1.05 +/- 0.15) cm(-1), and D-Mn = -(3.0 +/- 0.7) cm(-1) with J(1) describing the exchange through the phloroglucinol backbone and J(2) describing the exchange through the inner acetates. The non-necessity to incorporate the bridging outer acetates correlates with the longer Mn-O bonds. The experimental data can neither be analyzed without incorporating zero-field splitting nor by the application of a single effective spin ground state.

• 出版日期2010