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The one-dimensional supramolecular organization of single-molecule magnets (SMM) at low temperatures is analyzed, which is normally caused due to slow relaxation of its magnetization. The analysis reveals that the magnetic properties exhibited by the new complex lies between that exhibited by SMM and single-chain magnet (SCM) and are normally caused due to the chain arrangement of the molecules.

The ferricinium salt of the anionic, S=1/2, dithiolene complex [[N(tfadt)2].sup.-] (where tfadt is the asymmetrically substituted 2(trifluoromethyl)acrylonitrile-1,2-dithiolate) crystallizes at room temperature (rt) into uniform chains of dithiolene complexes, separated by ferricinium cations. Both ionic entities are characterized by disorder affecting one CF3 and one Cp moiety.

Three two-dimensional (2D) network compounds based on Mn(super III)/Mn(super II) tetranuclear single-molecule magnets (SMMs) connected by dicyanamide (dcn(super -)) linkers are synthesized. The use of SMMs as building blocks to design magnetic materials leads to new magnetic behaviors involving a competition between dynamics properties and the thermodynamic equilibrium.

Synthetic and structural evidence are provided to show that external coordination positions of Mn4/hmp rhombic single-molecule magnets (SMMs) are easily exchangeable and a one-dimensional rational assembly of the antiferromagnetically coupled [Mn4] SMM is obtained in a controlled manner by using a bridging bidentate coordinating anion like the azido anion. The experimental energy gap of tau is rationalized on the basis of the individual slow relaxation of the [Mn4] SMM and the magnetic correlations of the system.

The synthesis, crystal structures, and electronic band structure calculations, integrated with in-depth electron spin resonance and static susceptibility, dc conductivity, and (super 1)H spin-lattice relaxation studies of (EDT-TTF-CONH2)(sub 6)[Re6Se8(CN)(sub 6)] whose Kagome topology is unprecedented for any TTF-based materials are described.

The Mn(sub 4)/hmp single-molecule management (SMM) complexes that form a new family of complexes that fulfills the appealing assets of the Mn(sub 12) series is discussed. The new Mn(sub 4)/hmp derivative is the smallest complex to show all the known characteristic features for an SMM, opening new perspectives to understand the influence of the excited states on the quantum phenomena.

A series of analogous 2,6-disubstituted-spiro[3,3] heptane molecules, E(sub 2)C(sub 5)H(sub 8) and S/Se(3), is prepared and fully characterized. These molecules were also tested as rigid linkers in coordination of three-dimensional (3D) transition metal centers to afford linear or zigzag polymeric chains with M(hfac)(sub 2) units.

Nine dinuclear copper(II) complexes with hxta(super 5 -) ligands {H5hxta = N, NE -(2-hygroxy-1, 3-xylylene)-bis- (N-carboxymethylglycine)} are synthesized and characterized. The intra- and intermolecular magnetic interactions are quantified, and the coupling constants are related to the structural geometries.

Evidence for single-chain magnet behavior in an MnIII-NiII work opens new perspectives for one-dimensional systems to obtain high temperature metastable magnets by combining high spin magnetic units, strong interunit interactions, and uniaxial anisotropy. The synthesis, X-ray crystal structure, and magnetic properties of a unique one-dimensional heterometallic chain are discussed.

The structural and magnetic behavior of a greater range of solvated crystals of Co(sub 3)(dpa)(sub 4)Cl2, including the temperature dependences of both structures and magnetism are determined. The magnetic susceptibility measurements from 1.8 to 350 K indicate in each case that a gradual spin crossover, from a doublet to a quartet state, occurs over this temperature range.

The preparation and characterization of the three new linear compounds of the type Co3(dpa)(sub 4)X(sub 2) in which X = NCS-, CN- and N(CN)(sub 2)(super -) are reported. For all the compounds, the magnetic behavior is quite similar and as the temperature increases, the effective moments increase gradually, but since saturation is not reached, even at 400 K, the high-spin state cannot be assigned.

A study of the preparation and characterization of ionic compounds containing linear or zigzag chains of copper ions and linear tetracopper chain cation in [Cu4(DPhIP)(sub 4)][CuCl2](sub 2) is presented. The results show that the dimagnetic nature of the compound, molecular orbital calculations indicate that no direct Cu-Cu bonds are present, instead the bridging ligand effects a strong coupling of the spins.

Two crystalline forms of Di(2-pyridyl)amide (dpa),[Co(sub 3)(dpa)(sub- 4)(CH(sub 3)CN][PF(sub 6)](sub 2) are obtained from the same solution. Chiral crystals of both Delta and Alfa configurations have been isolated and determined by X-ray crystallography and their mirror-image circular dichroism spectra measured.

The series of M(sub 2)(hpp)(sub 4)Cl(sub 2) complexes from M = W to M = Pt are completed by preparation and characterization of those with M = W, Os, and Pt. W(sub 2)-(hpp)(sub 4)Cl(sub 2) has a W - W distance of 2.250(2) angstrom and is diamagnetic. Os(sub 2)(hpp)(sub 4)Cl(sub 2) has an Os - Os distance of 2.379(2) angstrom and displays small temperature independent paramagnetism while Pt(sub 2)(hpp)(sub 4)Cl(sub 2) has a Pt - Pt distance of 2.440(1) angstrom and is diamagnetic.

{NH(sub 2)(n-C(sub 12)H(sub 25))(sub 2)}(sub 3)[M(super III) = Fe, Cr) starting materials: [{Mn(salen)(EtOH)}(sub 3){M(CN)(sub 6)}] (M=Fe, 1; Cr, 2) are used to synthesize two cyano-bridged tetranuclear complexes composed of Mn(III) salen (salen =N, N'-ethylene bis(salicylideneiminate)) and hexacyanometalate(III) (M=Fe, Cr) in a stoichiometry of 3:1. The strong frequency dependence and observation of hysteresis on the field dependence of the magnetic indicate that Fe is a single-molecule magnet.

The magnetic properties of a giant Cu44 aggregate with 44 copper centers featuring two central bromide templates and a zeotypic superstructure is reported. A study of the magnetic field dependence on magnetization to get information on the magnetic properties shows that the problem is compounded by the presence of low lying magnetic states indicating that the individual clusters have nonzero spin ground states.