Sébastien Dhers

Design of one-dimensional coordination networks from a macrocyclic {3d-4f} single-molecule magnet precursor linked by [W(CN)8]3- anions.

The outcome of 1:1 reactions of the tetranuclear 3d-4f Single Molecule Magnet (SMM) [Cu3Tb(L(Pr))(NO3)2(H2O)]NO3 (1) with (TBA)3[W(CN)8] (TBA = tri-n-butyl ammonium cation, [(n-Bu)3N-H](+)) in dimethylformamide (DMF) is dependent on the crystallization method employed: liquid-liquid diffusion of the reagents together gives {[Cu3Tb(L(Pr))W(CN)8(DMF)4]·(DMF)}n (2) whereas diethyl ether vapor diffusion into the reaction solution gives {[Cu3Tb(L(Pr))W(CN)8(DMF)3(H2O)3]·(DMF)1.5·(H2O)0.5}n (3). Both compounds are obtained as black single crystals and feature one-dimensional (1D) coordination networks (chains) of [1](3+) macrocycles linked by [W(CN)8](3-) anions. The two assemblies differ from a structural point of view. Complex 2 has a stepped arrangement with the linkers bound to the opposite faces of the macrocycle, whereas 3 has a square-wave arrangement due to the linkers binding to the same face of the macrocycle. Both compounds display an antiferromagnetic ground state below 3.5 and 2.4 K with a metamagnetic and antiferromagnetic (T, H) phase diagram for 2 and 3, respectively. Remarkably the slow dynamics of the magnetization of the [1](3+) macrocycle units is preserved in 3 while this property is quenched in 2 because of stronger intra- and interchain magnetic interactions inducing a higher critical temperature.

A family of fourteen soluble stable macrocyclic [NiII3LnIII] heterometallic 3d–4f complexes

A family of fourteen tetranuclear, 3d–4f heterometallic nickel(II)–lanthanide(III) complexes of the hexaimine macrocycle (LPr)6−, with general formula NiII3LnIII(LPr)(NO3)3·xsolvents (LnIII = LaIII, CeIII, PrIII, NdIII, SmIII, EuIII, GdIII, TbIII, DyIII, HoIII, ErIII, TmIII, YbIII or LuIII), were prepared in a one-pot synthesis using a 3 : 1 : 3 : 3 reaction of nickel(II) acetate, the appropriate lanthanide(III) nitrate, the dialdehyde 1,4-diformyl-2,3-dihydroxybenzene (H2LAld) and 1,3-diaminopropane. In addition, three tetranuclear heterometallic nickel(II)–lanthanide(III) complexes of H2LAld, with general formula NiII3LnIII(LAld)3(NO3)3·xsolvents, were deliberately prepared (LnIII = LaIII, DyIII or YbIII) as in effect they represent intermediates en route to the above macrocyclic complexes. Whilst single crystals of the macrocyclic complexes were not forthcoming, X-ray crystal structure determinations on NiII3LnIII(LAld)3(NO3)3·xsolvents (LnIII = DyIII or YbIII) confirmed that the large ten-coordinate lanthanide(III) ion is bound in the central O6 pocket while the smaller six-coordinate nickel(II) ions are bound in the outer O4 pockets. In all fourteen cases, addition of the diamine to this intermediate (all in one pot) gives the tetrametallic [3 + 3] macrocyclic product. The magnetic properties of all fourteen macrocyclic complexes were measured down to 1.8 K to check for Single-Molecule Magnet behaviour, but no slow dynamics of magnetisation was observed.

Macrocyclic {3d–4f} SMMs as building blocks for 1D-polymers: selective bridging of 4f ions by use of an O-donor ligand

Crystallisation of the tetranuclear 3d-4f Single-Molecule Magnet (SMM) [CuTbIII(LEt)(NO3)3(MeOH)]·MeOH (1) with Na2[tpa] (tpa = terephthalate and H6LEt is the [3 + 3] imine macrocycle derived from 1,4-diformyl-2,3-dihydroxybenzene and 1,2-diaminoethane) gives a structurally characterised one-dimensional cationic polymer {[CuTbIII(LEt)(tpa)(H2O)3](NO3)·0.5H2O·0.25MeOH}n (2). A comparative study of the static and dynamic magnetic properties of 2 and its precursor, 1, is reported.

Probing the effect of arm length and inter- and intramolecular interactions in the formation of Cu(II) complexes of Schiff base ligands derived from some unsymmetrical tripodal amines

The syntheses of two previously known, 2-((2-aminoethyl)(pyridin-2-ylmethyl)amino)ethanol (1) and 2-((3-aminopropyl)(pyridin-2-ylmethyl)amino)ethanol (2), and four new unsymmetrical N-capped tripodal amines, 2-((4-aminobutyl)(pyridin-2-ylmethyl)amino)ethanol (3), 3-((2-aminoethyl)(pyridin-2-ylmethyl)amino)propan-1-ol (4), 3-((3-aminopropyl)(pyridin-2-ylmethyl)amino)propan-1-ol (5) and 3-((4-aminobutyl)(pyridin-2-ylmethyl)amino)propan-1-ol (6), are reported. The ligands (3–4) feature a longer arm, 3-hydroxypropyl or butylamino, than in the analogues previously employed (2-hydroxyethyl arm, ethylamino-arm or propylamino-arm in 1 and 2). All six tripodal amines, 1–6, are equipped with a 2-methylpyridyl-arm and either an ethylamino-arm (1 and 4), propylamino-arm (2 and 5) or butylamino-arm (3 and 6). The new amines, 3–6, have been employed in one pot condensation reactions with 2-hydroxy-1-naphthaldehyde and salicylaldehyde (and its derivatives) in the presence of Cu(II) metal ions to generate a series of new mononuclear complexes, [MIILaldi](ClO4) as well as new dinuclear complexes [CuIILaldi]2(ClO4)2 of new ligands Laldi. Four monomeric complexes and one dimeric complex have been characterised by single crystal X-ray diffraction, revealing a distorted square-pyramidal copper(II) ion. A general comparison between these structures shows that the number and types of chelate ring sequences around the metal ions are important in the formation of structures. Theoretical studies show that the 3-hydroxypropyl arm in these complexes is a weak coordinating group and it can readily be removed from the coordination sphere of metal ions, resulting in a dimerised four coordinate complex. Calculations show that the interaction between the two monomeric fragments is very weak.