Ligand design remains key to the synthesis of coordination compounds possessing specific topologies,nuclearities and symmetries that direct targeted physical properties.N,O-chelates based on ethanolamine have been par...Ligand design remains key to the synthesis of coordination compounds possessing specific topologies,nuclearities and symmetries that direct targeted physical properties.N,O-chelates based on ethanolamine have been particularly prolific in constructing a variety of paramagnetic 3d transition metal complexes with fascinating magnetic properties.Here,we show that combining three ethanolamine moieties within the same organic framework in the form of the pro-ligand 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane(LH_(3))leads to the formation of two highly unusual Mn wheels.Reaction of Mn(NO_(3))_(2)·6H_(2)O with LH_(3)in basic methanolic solutions leads to the formation of[Mn_(12)^(Ⅲ)Mn_(4)^(Ⅱ)(μ_(3)-O)_(6)(μ-OH)_(4)(μ_(3)-OMe)_(2)(μ-OMe)_(2)(L)_(4)(LH)_(2)(H_(2)O)_(10)](NO_(3))_(6)(OH)_(2)(1)and[Mn^(Ⅲ)_(10)(μ_(3)-O)_(4)(μ-OH)_(4)(μ-OMe)_(4)(L)_(4)(H_(2)O)_(4)](NO_(3))_(2)(2),the only difference in the synthesis being the ratio of metal:ligand employed.The structure of the former describes two offset[Mn_(6)^(Ⅲ)Mn_(2)^(Ⅱ)]square wheels,linked through a common centre,and the latter a single[Mn^(Ⅲ)_(10)]wheel twisted at its centre,such that the top half is orientated perpendicular to the bottom half.In both cases the L^(3−)/LH^(2−)ligands dictate the orientation of the Jahn-Teller axes of the Mn^(Ⅲ)ions which lie perpendicular to the triazacyclohexane plane.Direct current magnetic susceptibility and magnetisation data reveal the presence of competing exchange interactions in 1 and strong antiferromagnetic interactions in 2.Given the simplicity of the reactions employed and the paucity of previous work,the formation of these two compounds suggests that LH_(3)will prove to be a profitable ligand for the synthesis of a multitude of novel 3d transition metal complexes.展开更多
A new family of isomorphous[Cu_(4)Ln]clusters(Ln^(III)=Gd,Tb,Dy)with a‘propeller’-like topology was obtained from the use of naphthalene-2,3-diol in Cu^(II)/Ln^(III)chemistry;all complexes are ferromagneticallycoupl...A new family of isomorphous[Cu_(4)Ln]clusters(Ln^(III)=Gd,Tb,Dy)with a‘propeller’-like topology was obtained from the use of naphthalene-2,3-diol in Cu^(II)/Ln^(III)chemistry;all complexes are ferromagneticallycoupled and display either magnetocaloric properties or SMM behavior depending on the central Ln ion.展开更多
基金Hellenic Foundation for Research and Innovation(H.F.R.I.)under the“First Call for H.F.R.I.Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant”(Project Number:400)the EPSRC for financial support under grant reference numbers EP/I03255X/1 and EP/I031421/1.GL+1 种基金the Ministerio de Ciencia e Innovación(RTI2018-094909-J-I00)CSIC(PIE 201960E002).
文摘Ligand design remains key to the synthesis of coordination compounds possessing specific topologies,nuclearities and symmetries that direct targeted physical properties.N,O-chelates based on ethanolamine have been particularly prolific in constructing a variety of paramagnetic 3d transition metal complexes with fascinating magnetic properties.Here,we show that combining three ethanolamine moieties within the same organic framework in the form of the pro-ligand 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane(LH_(3))leads to the formation of two highly unusual Mn wheels.Reaction of Mn(NO_(3))_(2)·6H_(2)O with LH_(3)in basic methanolic solutions leads to the formation of[Mn_(12)^(Ⅲ)Mn_(4)^(Ⅱ)(μ_(3)-O)_(6)(μ-OH)_(4)(μ_(3)-OMe)_(2)(μ-OMe)_(2)(L)_(4)(LH)_(2)(H_(2)O)_(10)](NO_(3))_(6)(OH)_(2)(1)and[Mn^(Ⅲ)_(10)(μ_(3)-O)_(4)(μ-OH)_(4)(μ-OMe)_(4)(L)_(4)(H_(2)O)_(4)](NO_(3))_(2)(2),the only difference in the synthesis being the ratio of metal:ligand employed.The structure of the former describes two offset[Mn_(6)^(Ⅲ)Mn_(2)^(Ⅱ)]square wheels,linked through a common centre,and the latter a single[Mn^(Ⅲ)_(10)]wheel twisted at its centre,such that the top half is orientated perpendicular to the bottom half.In both cases the L^(3−)/LH^(2−)ligands dictate the orientation of the Jahn-Teller axes of the Mn^(Ⅲ)ions which lie perpendicular to the triazacyclohexane plane.Direct current magnetic susceptibility and magnetisation data reveal the presence of competing exchange interactions in 1 and strong antiferromagnetic interactions in 2.Given the simplicity of the reactions employed and the paucity of previous work,the formation of these two compounds suggests that LH_(3)will prove to be a profitable ligand for the synthesis of a multitude of novel 3d transition metal complexes.
基金supported by Brock University,NSERC-DG and ERA(to Th.C.S)the Ontario Trillium Foundation(graduate scholarship to D.I.A)+2 种基金Fundação para a Ciência e a Tecnologia(FCT,Portugal)for financial support to REQUIMTE/LAQV(UID/QUI/50006/2013)the MINECO(MAT2012-38318-C03,to M.E)the National Natural Science Foundation of China(grants 21371166,21331003 and 21221061 to J.T).
文摘A new family of isomorphous[Cu_(4)Ln]clusters(Ln^(III)=Gd,Tb,Dy)with a‘propeller’-like topology was obtained from the use of naphthalene-2,3-diol in Cu^(II)/Ln^(III)chemistry;all complexes are ferromagneticallycoupled and display either magnetocaloric properties or SMM behavior depending on the central Ln ion.
