Assisted Self‐Assembly to Target Heterometallic Mn‐Nd and Mn‐Sm SMMs: Synthesis and Magnetic Characterisation of [Mn 7 Ln 3 (O) 4 (OH) 4 (mdea) 3 (piv) 9 (NO 3 ) 3 ] (Ln=Nd, Sm, Eu, Gd)**
Résumé
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, whereas 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 because 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 magnetisation for these compounds was confirmed by ac measurements above 1.8 K.
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