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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 have been 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.

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.

Chemical oxidation of the linear tricobalt compound CO3(dpa)4C12 with NOBF4 yields (Co3(dpa)4C12)+, a one-electron oxidized species.

Research is presented demonstrating a spiroconjugated nitronyl nitroxide biradical's crystal structure, synthesis, magnetic and electron paramagnetic resonance properties. Density functional calculations are used to present evidence for a spiroconjugation exchange pathway.

Research has been conducted on the compounds containing Cr (sub)3 (dipyridylamide) (sub)4 (super)2+ cores. The preparation of the compounds and their magnetic properties are discussed.

Salts containing the dinuclear anion (M(sub.2)Cl(sub.6))(super.2-) (M = Mn, Fe, Co) are discussed relative to magnetic properties, structures and reactivities. The edge-sharing bitetrahedral anion was isolated with 5 different cations. The electronic ground state of the ion is orbitally degenerate and highly anisotropic, a conclusion confirmed with magnetic data. The bridging ligand mediates antiferromagnetic exchange. The D parameter is large and negative. High-spin polynuclear transition metal compounds are of interest for magnetic properties for biological use and for materials chemistry. Iron, or ferrous, compounds have not been studied well vs ferric systems.

Research was conducted to examine the magnetic transitions in the cyano-bridged bimetallic ferromagnet Mn2(H2O)5Mo(CN)7*4.75H2O (beta phase). The temperature and field dependence of the magnetization were measured along the magnetic axes. Single crystal magnetic calculations demonstrated that the compound orders ferromagnetically at T(sub c) = 51 K without a hysteresis effect. The compound was also found to have a complex magnetic phase diagram when the field was applied along the a direction with various ferromagnetically ordered domains and a spin reorientation domain.

Research was conducted to examine the structure, the single-crystal magnetic properties, anisotropy and spin reorientation for the two-dimensional cyano-bridged bimetallic compound K2Mn3(H2O)6(Mo(CN)7)2*6H2O. Dc and ac magnetic measurements were performed and the magnetic phase diagram of the compound was determined. Results suggest that the compounds are ferromagnets and exhibit many interesting features in addition to the ferromagnetic ordering.

The magnetic anisotropy, ferromagnetic ordering and spin reorientation of the cyano-bridged bimetallic compound Mn2(H2O)5Mo(CN)7*4H2O were described. The compound was synthesized by slow diffusion of aqueous solutions with K4-(Mo(CN)7)*2H2O and (Mn(H2O)6)(NO3)2. The unique magnetic phase diagram of the compound was also determined. In addition, the origins of the magnetic anisotropy and the mechanism of the ferromagnetic interaction between low-spin Mo(super 3+) and high-spin Mn(super 2+) ions through the cyano bridge were examined.

{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.

The heterometallic linear tertramers [Mn(5-R-saltmen)Ni(Pao)(bpy)(sub 2)](sub 2-)(ClO4)(sub 4) (5-R-saltmen(super 2-) = N,N'-1,1,2,2-tetramethylethylene bis(5-R-salicylideneiminate); pao(super -) = pyridine-2-aldoximate; bpy = 2,2'-bipyridine, R = H, 1; Cl, 2; Br, 3; MeO 4) are synthesized and structurally characterized. The magnetic measurements on these tetramers confirm the nature of the magnetic interaction reported for the Mn(super III)(sub 2)-Ni(super II) chains.

The compound Ni3(dpa)4Cl2 (dpa = di(2-pyridyl)amido anion) was prepared in two new crystal forms, Ni3(dpa)4Cl2*2CH2Cl2 and Ni3(dpa)4Cl2*THF. The two forms were studied structurally and the magnetic properties of one of them were obtained from 2 to 300 K and the proton NMR spectrum was recorded. Findings showed that the molecular structure is invariant in the three crystalline forms and has a symmetrical chain of nickel atoms, the terminalf metal atoms each have two unpaired electrons, and the magnetic moments of the two terminal nickel(II) ions showed antiferromagnetic coupling.

The reaction of ([Bu.sub.4]N)CN with Re[Cl.sub.4][(THF).sub.2] has helped in the synthesis of a high-anisotropy building unit, trans-[[Re[Cl.sub.4][(CN).sub.2]].sup.2-], which has represented the paramagnetic complex with a mixture of cyanide and halide ligands. The field-dependent magnetization of the iron congener has displayed a major hysteresis effect at low temperature, thus showing magnetlike behavior in this one-dimensional system.

The article presents a new approach, which employs the dinuclear metallacyclic complex [[[Ni.sub.2][(mbpb).sub.3]].sup.2-] [[H.sub.2]mbpb = 1,3-bis(pyridine-2-carboxamide)benzene] for the construction of the various 3d-3d-4f chain complexes.

The synthesis of protein-sized chiral [Fe.sub.168] cages with NbO-type topology is reported. The synthesis involved the introduction of L- and D-tartrate ligands into the [Fe.sup.3+]/formate/[Na.sup.+] systems that exhibited alcohol-guest sorption properties.

The synthesis, structural characterization, and magnetic properties of pentanuclear dysprosium compound [[Dy.sub.5][([[mu].sub.3]-OH).sub.4][([mu]-[[eta].sup.2]-[Ph.sub.2]acac).sub.4][([[eta].sup.2]-[Ph.sub.2]acac).sub.6]] (where [Ph.sub.2]acac = dibenzoylmethanide) is described. The results from both static and dynamic magnetic properties showed slow relaxation of the magnetization below 3 K typical for single-molecule magnets.

The synthesis of two dodecanuclear copper(II) cages by a multicomponent reaction strategy involving a copper(II) salt, an ancillary pyrazole ligand and triethyl amine is described. The nuclease activity of these cages is studied and has disclosed that both of them are effective nucleases in the presence of an external oxidant.

The synthesis, structural characterization and magnetism of a [[L.sub.2][Ni.sub.2]Ln][Cl[O.sub.4] family of compounds is reported. The new compounds with mixed metal 3d/4f single-molecule magnet were obtained by the reaction of L[H.sub.3] with Ni[(Cl[O.sub.2]).sub.2].6[H.sub.2]O and lanthanide salts in a 2:2:1 ratio in the presence of triethylamine.

The manganese phosphorus cluster containing an unusual [Mn.sub.5][P.sub.7] core structure and three short Mn-Mn distances is obtained from the reaction of Mn[{N[(Si[Me.sub.3]).sub.2]}.sub.2] with [H.sub.2]PSi/[Pr.sub.3]. Quantum chemical examinations have shown the presence of strong intramolecular antiferromagnetic interactions leading to a total S = 5/2 spin ground state, which is confirmed by magnetic measurements.