An oxide-bridged Dy–ReV–Dy single-molecule magnet

The reaction of diamagnetic trans-[ReV(O)2(py)4]NO3 with [Ln(hfac)3(H2O)2] (Ln = Dy, Y, Tb; hfac− = 1,1,1,5,5,5-hexafluoroacetylacetonate(1–)) in chloroform yields oxide-bridged, trinuclear [Ln(hfac)3(H2O)–Re(O)2(py)4–Ln(hfac)3(NO3)] (DyReDy, YReY, TbReTb). The series is isostructural to a fluoride-bridged {Dy–Cr–Dy} complex previously reported (Dreiser et al., Chem. Sci. 3 (2012) 1024) but, notably, DyReDy exhibits frequency-dependent out-of-phase ac susceptibility (χ″) signals at higher temperatures than the chromium analogue. Magnetic investigations of a solid solution of Dy3+ in YReY reveal the presence of a small Dy–Dy exchange interaction in DyReDy.

Graphical abstractUse of diamagnetic trans-[ReV(O)2(py)4]+ moiety as a bridging metallo-ligand, provides a magnetically simpler analogue of a fluoride-bridged {Dy–Cr–Dy} complex. Magnetic studies of this compound and a magnetically diluted analogue allow for a direct observation of weak Dy–Dy interactions.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► First use of diamagnetic trans-[ReV(O)2(py)4]+ moiety as a bridging metallo-ligand. ► Direct observation of weak Dy–Dy interaction by magnetic dilution experiments. ► Observation of two distinct magnetic relaxation pathways.