7 research outputs found
La molécule dans le solide : du complexe isolé à l'aimant
International audienc
Dynamics at T->0 in half-integer isotropic high spin molecules
We investigate the dynamical spin-spin auto-correlation function of the
isotropic high spin molecules CrCu (S=9/2), CrNi (S=15/2) and
CrMn (S=27/2), using magnetization, SR and NMR measurements. We find
that the field autocorrelation time of the molecule's spin at zero and
low fields is nearly temperature independent as mK. The high
temperatures is very different between the molecules. Surprisingly, it
is identical ( 10 nsec) at low temperature. This suggests that is
governed by hyperfine interactions.Comment: 5 pages, 5 figures. To be published in PRB Breif Report (March 2002
Cyanide Compounds
Chapter 4, “Cyanide Compounds,” illustrates an explosively developing research theme in which the cyanide ligand is used as a linking agent for the designed assembly of polynuclear metal complexes. Syntheses of several basic building blocks, such as K3[Cr(CN)6],Cr(Me3tacn)(CN)3,K4[Mo(CN)8],Na[W(CO)5CN],K[CpFe(CO)(CN)2],[NEt4][Cp*Rh(CN)3],[Fe4(bpy)8(μ-CN)4][PF6]4,. are given here. These units may be used in several ways to construct polynuclear compounds. One approach involves a hexacyanometalate core decorated with peripheral metal centers, e.g., [{Cu(tpa)(CN)}6Fe][ClO4]8. or [Cr{CNNi(tetren)}6][ClO4]9. An octacyanometalate unit can lead to higher nuclearity condensed compounds, as in [Co{Co(MeOH)3}8(μ-CN)30{Mo(CN)3}6]. Alternatively, a cluster core may be substituted with cyano complexes as ligands, as in [PPh4]2[Fe4S4{NCW(CO)5}4]. If there are two cis cyano ligands on the building block, then quadrilateral or square structures often result, as in {CpFe(CO(μ-CN)2Cu(PCy3)}2 and [Fe2Cu2(bpy)6(μ-CN)4][PF6]4 However, if there are three adjacent cyano ligands, then cubic cages may be constructed as in [(CpCo)4(Cp*Rh)4(μ-CN)12][PF6]4