Syntheses, structures, and magnetic properties of a series of Mn–M–Mn trinuclear complexes with different spin configurations†
A series of trinuclear complexes, [MnII2YIII(L)2(HL)2(NO3)3][YIII(NO3)5]·7H2O (1′), [MnII2GdIII(HL)4(NO3)4]2[MnII2GdIII(L)(HL)3(NO3)4][GdIII(NO3)5]4·2(o-Xy)·12H2O (2′) and [MnII3(L)(HL)2(NO3)4](NO3)·1.25(p-Xy) (3′), were synthesized using a β-diketone ligand HL (HL = 1,3-bis(pyridin-2-yl)propane-1,3-dione). X-ray structural analyses revealed that each complex has a trinuclear core with an Mn(II)–M–Mn(II) arrangement (M = YIII (1), GdIII (2), and MnII (3)). In 1′ with a diamagnetic Y(III) ion, negligible antiferromagnetic interactions between terminal Mn(II) ions are operative. On the other hand, 2′ shows ferromagnetic interactions between Mn(II) and Gd(III) ions, affording a spin ground state of ST = 17/2. The homometallic Mn(II)3 complex of 3′ has an ST = 5/2 spin ground state resulting from the antiferromagnetic interactions between neighboring Mn(II) ions. The maximum magnetic entropy change (−ΔSm) of 1′–3′ was estimated to be 12.3, 24.8, and 8.0 J kg−1 K−1, respectively.