A family of dodecanuclear Mn11Ln single-molecule magnets

A series of four isostructural dodecanuclear complexes [MnIII9MnII2LnIII(O)8(OH)(piv)16(NO3)(CH3CN)]·xCH3CN·yC7H16 (piv = pivalate; x = ½, y = ¾, Ln = Tb (1); x = 2, y = ½, Ln = Dy (2), Ho (3), and Y (4)) has been prepared for which the structural motif described as ‘a lanthanide ion nested in a large manganese shell’ is observed. All compounds show out-of-phase signals in their ac susceptibilities, and their single-molecule magnet behaviour was confirmed by single-crystal micro-SQUID studies of 1-3 which show hysteresis loops of molecular origin at T < 1.0 K. The SMM behaviour observed in compounds 1-3 is more pronounced than that for 4, which contains the diamagnetic YIII ion. This is principally the result of ferromagnetic coupling between the paramagnetic anisotropic LnIII ions (TbIII, DyIII and HoIII) and the manganese shell, which enhances the total spin ground state of the complexes.