Assisted self-assembly to target heterometallic Mn-Nd and Mn-Sm SMMs: Synthesis and magnetic characterisation of [MnIII7Ln3(O)4(OH)4(mdea)3(piv)9(NO3)3] (Ln = Nd, Sm, Eu, Gd).

In an assisted self-assembly approach starting from the [Mn 6 O 2 (piv) 10 (4-Me-py) 2 (pivH) 2 ] cluster a family of Mn-Ln compounds (Ln=Pr-Yb) was synthesised. The reaction of [Mn 6 O 2 (piv) 10 (4-Me-py) 2 (pivH) 2 ] ( 1 ) with N -methyldiethanolamine (mdeaH 2 ) and Ln(NO 3 ) 3 ·6H 2 O in MeCN generally yields two main structure types: for Ln=Tb-Yb a previously reported Mn 5 Ln 4 motif is obtained, while for Ln=Pr-Eu a series of Mn 7 Ln 3 clusters is obtained. Within this series the Gd III analogue represents a special case since it shows both structural types as well as a third Mn 2 Ln 2 inverse butterfly motif. Variation in reaction conditions allows access to different structure types across the whole series. This prompts further studies into the reaction mechanism of this cluster assisted self-assembly approach. For the Mn 7 Ln 3 analogues reported here variable-temperature magnetic susceptibility measurements suggest that antiferromagnetic interactions between the spin carriers are dominant. Compounds incorporating Ln=Nd III ( 2 ), Sm III ( 3 ) and Gd III ( 5 ) display SMM behaviour. The slow relaxation of the magnetization for these compounds was confirmed by ac measurements above 1.8 K.