title: Ferromagnetic Polarization: The Quantum Picture of Switching On/Off Single-Molecule Magnetism.
abstract: The mixed 3d-4f pentanuclear complex (Bu4N)[Mn(III)4Y(III)(shi)4(OAc)4(CH3OH)4]·CH3OH·H2O (1) (H3shi = salicylhydroxamic acid) was synthesized by the direct reaction of Y(NO3)3·6H2O, Mn(OAc)2·4H2O, and H3shi. When an additional ligand, (NHBu3)3[W(CN)8]·2H2O, was added, the mixed 3d-4f-5d hexanuclear complex (Et4N)5[Mn(III)4Y(III)(shi)4(OAc)4W(V)(CN)8](WO4)0.5 (2) was obtained. X-ray crystallographic analysis shows that the 3d-4f complex 1 represents a 12-metallacrown-4 (12-MC-4) structure, in which the metallacrown ring [Mn-N-O]4 connection captures one Y(III) ion with four bridging acetate anions, completing the eight-coordinated environment around Y(III) ion, while four methanol molecules each coordinate to the Mn(III) ions on the other side of the Y(III) ion. After octacyanotungstate is introduced, the [W(V)(CN)8] group substitutes for four methanol molecules of 1 to form complex 2. Magnetic studies indicate the overall antiferromagnetic coupling present within the MC ring of complex 1. However, interestingly, the dominant ferromagnetic coupling between Mn(III) ions was observed in complex 2. A susceptibility analysis shows that the natural spin alignments in 12-MC-4 metallacrowns are tuned from overall antiferromagnetic to dominant ferromagnetic fashions by magnetic coupling between Mn(III) ions and the W(V) ion. Complex 1 [Mn(III)4Y(III)] retains an S = 0 ground state, and complex 2 [Mn(III)4Y(III)W(V)] shows obvious single-molecule magnet (SMM) behavior with an ST = 11/2 ground state, respectively, before and after introduction of the octacyanotungstate group. The spin frustration geometrical structure constructed by four Mn(III) ions and one W(V) ion was considered as the key factor for switching on the SMM properties of the 12-MC-4 system.
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210046, People's Republic of China.|School of Chemistry and Chemical Engineering, Liaocheng University , Liaocheng 252059, People's Republic of China.
authors.forename: Fan
authors.initials: F
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210046, People's Republic of China.
authors.forename: Rong-Min
authors.initials: RM
authors.lastname: Wei
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210046, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210046, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210046, People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Han
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210046, People's Republic of China.
authors.forename: You
authors.initials: Y
authors.lastname: Song
authors.affiliation: School of Chemistry and Chemical Engineering, Liaocheng University , Liaocheng 252059, People's Republic of China.
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Dou