Two Heterometallic Nanoclusters [Dy₄^III Ni₈^II] and [Dy₁₀^IIIMn₄^IIIMn₂ ^II]: Structure, Assembly Mechanism, and Magnetic Properties

A full understanding of the assembly mechanisms of coordination complexes is of great importance for a directional synthesis under control. We thus explored here the formation mechanisms of the two new heterometallic nanoclusters [(DyIIINiII8)-Ni-4(mu(3)-OH)(8)(L)(8)(OAc)(4)(H2O)(4)]center dot 3.25EtOH center dot 4CH(3)CN (1) and [(Dy10Mn4Mn2O4)-Mn-III-Mn-III-O-II(OH)(12)(OAc)(16)(L)(4()HL)(2)(EtOH)(2)]center dot 2EtOH center dot 2CH(3)CN center dot 2H(2)O (2) with different cubane-based squarelike ring structures, which were obtained from the reactions of 4-bromo-2-[(2-hydroxypropylimino)methyl]phenol (H2L) with Dy(NO)(3)center dot 6H(2)O and the transition metal salt Ni(OAc)(2)center dot 4H(2)O or Mn(OAc)(2)center dot 4H(2)O. The high-resolution electrospray ionization mass spectrometry (HRESI-MS) tests showed that the skeletons of clusters 1 and 2 have a high stability under the measurement conditions for HRESI-MS. The intermediates formed in the reaction courses of clusters 1 and 2 were tracked using time-dependent HRESI-MS, which helped to determine the proposed hierarchical assembly mechanisms for 1 (H2L -> NiL -> Ni2L2 -> Ni3L4 -> Ni4L4 -> DyNi4L5 -> Dy2Ni6L6 -> Dy3Ni6L6 -> Dy3Ni7L7 -> Dy4Ni8L8) and 2 (H2L -> MnL -> DyMnL -> DyMn2L -> Dy2Mn2Lx -> Dy8Mn2L2 -> Dy10Mn2L2 -> Dy10Mn6Lx and H2L -> DyL -> Dy4L2 -> Dy6L2 -> Dy8Mn2L2 -> Dy10Mn2L2 -> Dy10Mn6Lx). This is one of the rare examples of investigating the assembly mechanisms of 3d-4f heterometallic clusters. Magnetic studies indicated that the title complexes both show slow magnetic relaxation behaviors and cluster 1 is a field-induced single-molecule magnet.