Magnetic Interactions in a Series of Homodinuclear Lanthanide Complexes

A series of seven isostructural homodinuclear lanthanide complexes are reported. The magnetic properties (ac and dc SQUID measurements) are discussed on the basis of the X-ray structural properties which show that the two lanthanide sites are structurally different. MCD spectroscopy of the dysprosium­(III) and neodymium­(III) complexes ([Dy^III₂(L)­(OAc)₄]⁺ and [Nd^III₂(L)­(OAc)₄]⁺) allowed us to thoroughly analyze the ligand field, and high-frequency EPR spectroscopy of the gadolinium­(III) species ([Gd^III₂(L)­(OAc)₄]⁺) showed the importance of dipolar coupling in these systems. An extensive quantum-chemical analysis of the dysprosium­(III) complex ([Dy^III₂(L)­(OAc)₄]⁺), involving an ab initio (CASSCF) wave function, explicit spin–orbit coupling (RASSI-SO), and a ligand field analysis (Lines model and Stevens operators), is in full agreement with all experimental data (SQUID, HF-EPR, MCD) and specifically allowed us to accurately simulate the experimental χ<i>T</i> versus <i>T</i> data, which therefore allowed us to establish a qualitative model for all relaxation pathways

Synthesis and Characterization of Multinuclear Manganese-Containing Tungstosilicates

The five manganese-containing, Keggin-based tungstosilicates [Mn^II₃(OH)₃­(H₂O)₃(<i>A</i>-α-SiW₉O₃₄)]^7– (<b>1</b>), [Mn^III₃(OH)₃­(H₂O)₃(<i>A</i>-α-SiW₉O₃₄)]^4– (<b>2</b>), [Mn^III₃(OH)₃­(H₂O)₃(<i>A</i>-β-SiW₉O₃₄)]^4– (<b>3</b>), [Mn^III₃Mn^IVO₃­(CH₃COO)₃(<i>A</i>-α-SiW₉O₃₄)]^6– (<b>4</b>), and [Mn^III₃Mn^IVO₃­(CH₃COO)₃(<i>A</i>-β-SiW₉O₃₄)]^6– (<b>5</b>) were synthesized in aqueous medium by interaction of [<i>A</i>-α-SiW₉O₃₄]^10– or [<i>A</i>-β-SiW₉O₃₄H]^9– with either MnCl₂ (<b>1</b>) or [Mn^III₈Mn^IV₄O₁₂(CH₃COO)₁₆(H₂O)₄] (<b>2</b>–<b>5</b>) under carefully adjusted reaction conditions. The obtained salts of these polyanions were analyzed in the solid state by single-crystal X-ray diffraction, IR spectroscopy, and thermogravimetric analysis. The salts of polyanions <b>1</b>, <b>2</b>, and <b>4</b> were further characterized in the solid state by magnetic studies, as well as in solution by electrochemistry