Ultrasound‐Assisted Formation of {Fe₆Ln/Y₄} Wheel‐Shaped Clusters and Condensed {Fe₄Ln/Y₂} Aggregates

Abstract

Two families of charge‐neutral heterometallic Fe‐4f coordination compounds comprising isobutyrate and amino alcoholate linkers were found to form exclusively upon ultrasonication irradiation. Under one‐pot conditions, the trinuclear precursor [Fe 3 O(O 2 CCHMe 2 ) 6 (H 2 O) 3 ](NO 3 ) · 2(MeCN) · 2(H 2 O) reacts with Ln(NO 3 ) 3 · x H 2 O or Y(NO 3 ) 3 · 6H 2 O, N‐butyldiethanolamine (bdeaH 2 ) and NaN 3 in methanol to yield the decanuclear clusters [Fe 6 M 4 (O 2 CCHMe 2 ) 8 (N 3 ) 2 (bdea) 10 ] · n (solvent) (M III = Y ( 1a·3MeOH ), Gd ( 2a·2.5MeOH ), Dy ( 3a·3.5MeOH·0.5H 2 O ), Tb ( 4a·2MeOH ), Ho ( 5a·2MeOH ), as well as subsequently the hexanuclear compounds [Fe 4 M 2 (OH) 2 (O 2 CCHMe 2 ) 6 (N 3 ) 2 (bdea) 4 ] · 2(solvent) (M III = Y ( 1b·2MeOH ), Gd ( 2b·2MeOH ), Dy ( 3b·2MeOH, 3c·2EtOH ), Tb ( 4b·2MeOH ), Er ( 6b·2MeOH ), Tm ( 7b·2MeOH )). The {Fe 6 M 4} clusters feature a wheel‐shaped architecture with the metal ions, interlinked by carboxylate and polyalcoholamine bridges, forming a saddle‐like ring. The hexanuclear {Fe 4 M 2} clusters comprise two {Fe 2 M} triangles, connected via two bridging µ 3 ‐OH – groups, which form a condensed core of metals additionally linked by deprotonated tripodal bdeaH 2 ligands and bridging carboxylates. Magnetic measurements revealed predominant strong antiferromagnetic interactions within compounds 1 – 7 and out‐of‐phase signals for {Fe 6 Dy 4} ( 3a·3.5MeOH·0.5H 2 O ), {Fe 6 Tb 4} ( 4a·2MeOH ), and {Fe 4 Dy 2} ( 3b·2MeOH ).