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Two new one-dimensional azide-bridged manganese(III) coordination complexes as well as a mononuclear complex are obtained by changing ancillary tetradentate Schiff base ligands (L). Magnetic characterization has shown that the [[mu].sub.1,3]-bridging azide ion has transmitted antiferromagnetic interaction between [Mn.sup.III] ions, but these complexes have displayed various magnetic behaviors at low temperatures.

The reaction of Cu[Cl.sub.2] with 2-amino-5-fluoropyridine and HCl in aqueous solution has produced bis(2-amino-5-fluoropyridinium)tetrachlorocuprate(II). The first-principles bottom-up studies have shown that at low temperature the crystal complex has a three-dimensional magnetic topology and a singlet ground state.

The synthesis, crystal structure, magnetic properties, and theoretical study of the 1dimensional coordination polymer [[Cu[([mu].sub.11]-[N.sub.3]).sub.2]Cu[([mu].sub.1,1]-[N.sub.3])].sub.2]Cu].sup.2} is described.

The spin levels and magnetic properties of two polyoxometalates (POMs), two novel polyoxotungstates containing [Cu.sub.6.sup.12} and [Mn.sub.6.sup.12} hexagons is demonstrated.

The evidence for magnetic susceptibility of synthetic libethenite [Cu.sub.2]P[O.sub.4]OH by using an isolated square-spin cluster model defined by the CuI-O-Cu2 superexchange is reported.

A detailed study of a triply interpenetrating three-dimensional (3D) spin crossover (SC) coordination polymer [Fe[(4ditz).sub.3]][(P[F.sub.6]).sub.2]*solv is reported whose magnetic properties could be tuned by inclusion of a different solvent. Both methanol and ethanol solvents show an abrupt two-step spin crossover from low spin (S = 0) to high spin (S = 2) with the methanolate curve lying 7 K higher and showing a small hysteresis.

The synthesis, crystal structure and magnetic properties of a new series of isostructural trinuclear compounds of formula [(N[Bu.sub.4]).sub.2][[{[Re.sup.IV][Cl.sub.4]([mu]-ox)}.sub.2][Mn.sup.II][(Him).sub.2]] (N[Bu.sub.2.sup.} = tetra-n-butylammonium cation, ox = oxalate dianion, Him = imidazole, M = Mn, Co, Ni, Cu. The magnetic susceptibility measurements on polycrystalline samples have shown the occurrence of remarkable intramolecular antiferro- and ferromagnetic interactions.

X-ray diffraction, ESI-MS, IR and UV-vis spectroscopy, electrochemistry and magnetic susceptibility are used to synthesize and characterize complexes of Cu(II) derived from two new nonfacially coordinating heteroscorpionate ligands. It shows that the labile water or halide ligands on various metal dimers can be substituted by various exogenous carboxylates.

The ferroelectric, magnetic and magnetoelectric properties of [Pb.sub.1-x][Ba.sub.x]([Fe.sub.0.5][Ti.sub.0.5])[O.sub.3] system, where x= 0.2 and 0.4, are reported. The effect of magnetic and direct current (dc) electric polings on ferroelectric and magnetic hysteresis loops is measured to show the magnetoelectric coupling between the electric dipoles and magnetic dipoles at room temperature.

The syntheses and characterization of the crystal and magnetic structures of the mixed-anion coordination polymer Cu(HC[O.sub.2])(N[O.sub.3])(pyz) (where pyz = pyrazine) was characterized. The Cu(HC[O.sub.2])(N[O.sub.3])(pyz) undergoes a long-range magnetic ordering due to the one-dimensional Cu[(N[O.sub.3]).sub.2](pyz) and three-dimensional Cu[(HC[O.sub.2]).sub.2](pyz) compounds which display linear chain antiferromagnetism with no long-range magnetic ordering down to 2 K.

The orientation of crystals of the giant magnetostrictive compound Terfenol-D solidified in a static magnetic field is investigated. Experimental results show that on the condition of slow cooling in the presence of a static magnetic field, free crystal nuclei of these materials in high temperature melt are easily be induced and aligned with their easy magnetic axes along the field at the beginning of the solidification.

The syntheses, structures and magnetic properties of unprecedented two-dimensional (2D) layered Cu(II)-M(V) complexes [Cu(L)](sub 3n)[M(CN)(sub 8)](sub 2n).6nH2O (M = Mo (2), W (3) and L = macrocyclic ligand) with honeycomblike structures, formed by self-assembling [Cu(L)](super 2+) (1) and [M(CN)(sub 8)](super 3-) in a ratio of 3:2 are described. The temperature- and field-dependent magnetic features show that paramagnetic Cu(II) and M(V) centers are ferromagnetically and antiferromagnetically coupled through cyanide bridges.

The quinoid metal complexes are potentially very interesting molecular-based materials because they couple charge distribution bistability for magnetic proplutes. The systems offers exciting properties to be measured on individual molecules with STM and related techniques when organized properly on suitable surfaces.

Thiocyanatonickel(II) compounds with composition {[(As[Ph.sub.4]).sub.2][Ni[(NCS).sub.4]]} 1, {(Cat)[Ni[(NCS).sub.4]]} 2, {(As[Ph.sub.4]).sub.4][[Ni.sub.2][(NCS).sub.8]] } 3, {[(Cat).sub.2] [[Ni.sub.2][(NCS).sub.8]]*2[CH.sub.3][NO.sub.2]} 4, and {[([Et.sub.4]N).sub.4][Ni[(NCS).sub.6]]} 5 ([Cat.sup.2+] = [(p-xylylenebis(triphenyphosphonium)).sup.2+]) were prepared. The crystal structures of compounds 1, 3, and 4 were determined. Compound 1 crystallizes in the monoclinic C2/c space group with a = 22.761(2) [Angstrom], b = 15.055(1) [Angstrom], c = 15.054(1) [Angstrom], [beta] = 108.915(1)[degrees], V = 4879.9(6) [Angstrom].sup.3], and Z = 4. Compound 3 crystallizes in the triclinic P1 space group with a = 11.2183(6) [Angstrom], b = 14.2551(8) [Angstrom], c = 16.629(1) [Angstrom], [alpha] = 79.326(1)[degrees], [beta] = 73.605(1)[degrees], [gamma] = 75.496(1)[degrees], V = 2451.0(2) [Angstrom].sup.3], Z = 2. Compound 4 crystallizes in the monoclinic [P2.sub.1]/n space group with a = 13.1148(9) [Angstrom], b = 27.128(2) [Angstrom], c = 14.882(1) [Angstrom], [beta] = 114.056(2)[degrees], V = 4834.8(6) [[Angstrom].sup.3], Z = 4. The magnetic properties of compounds 1-4 were studied over the 2-300 K temperature range. Compounds 1 and 2 with monometallic [Ni[(NCS).sub.4]].sup.2-] complex units have similar magnetic properties, in agreement with nickel(II) ions in pseudo-tetrahedral environments. Compounds 3 and 4 with bimetallic [[[Ni.sub.2][(NCS).sub.8]].sup.4-] complex units exhibit magnetic properties, which are indicative of Ni(II)-Ni(II) ferromagnetic interactions with zero-field splitting effects caused by the pseudo-square-pyramidal or pseudo-trigonal-bipyramidal coordination environments of the nickel(II) ion in compounds 3 and 4, respectively. The structures and magnetic results for all compounds are correlated with NIR--UV--vis absorption spectra. Key words: nickel(II) thiocyanato complexes, crystal structures, paramagnetism, molecular magnetism, exchange coupling, absorption spectroscopy.

The structural characterization of newly synthesized donor molecule, ethylenedithiodiselenadithiafulvalenoquinone-1,3-diselenolemethide (EDT-DSDT-FVODS) is reported. The compound exhibit unique arrangement of canted one-dimensional antiferromagnetic d-spin chains and neighboring d-spin chains with reverse spin directions.

The synthesis and characterization of a new carboxylato-bridged [Co.sup.II]thiophenedicarboxylic acid (TDC) compound is presented. The title compound has shown an unprecedented asymmetric tetradentate coordination mode of the carboxylate functions and the magnetic measurements have shown weak ferromagnetic interactions between the Co ions within the dimers.

A [Dy.sub.4.sup.III][Mn.sub.6.sup.III] complex with a metallacrown (MC)-like topology, which possesses frequency-dependent magnetic behavior, was explored to determine its possible single-molecule magnet behavior. The observation has showed that simple substitution of lanthanide cations in mixed [Ln.sup.III]-TM complexes has affected the nature of the low-temperature magnetic behavior, so ([Dy.sub.4.sup.III][Mn.sub.6.sup.III]) has exhibited a behavior that is consistent with single-molecule magnetism while ([Ho.sub.4.sup.III][Mn.sub.6.sup.III]) did not.

Reversible vapochromic behavior of a porous copper(II) coordinator polymer constructed from a flexible hinglelike ligand is investigated by adsorption measurements. The isotherms show large hysteretic and stepwise profiles, suggesting the occurrence of the guest-induced framework transformation.

The synthesis of four new enneanuclear Mn/Ce clusters containing the [[Ce.sup.IV][Mn.sup.III.sub.8][O.sub.8]](12+) core which comprises a saddlelike loop with a central [Ce.sup.IV] ion is reported. The results revealed these complexes as new structural types of single-molecule magnets (SMMs) whose intermolecular interactions are mediated by hydrogen-bonding interactions with lattice-water molecules of crystallization.

The syntheses, structures and magnetic properties of three hybrid organic-inorganic coordination polymers with benzenepentacarboxylate (BPCA) linkers are described. These compounds are the first examples of coordination polymers with benzenepentacarboxylate linkers and has filled the gap of coordination polymers involving benzenepolycarboxylate linkers of [C.sub.6][H.sub.6-n][(COOH).sub.n] (n = 2-6).

The synthesis of two new different heterometallic cubane single-molecule magnets is described. The analysis of the magnetization and magnetic field show that both the complexes are single-molecules magnets.

The reversible guest-induced magnetic and structural single-crystal-to-single-crystal transformation in microporous coordination network [{[[Ni(cyclam)].sub.3][[W[(CN).sub.8]].sub.2]}.sub.n] is studied. The compound is found to exhibit reversible water adsorption at low temperature.

The neutral layers of the bimetallic oxalate complex [{[Co[([H.sub.2]O).sub.2].sub.3][[Cr[(ox).sub.3]].sub.2]}.sub.[infinity]] are constituted in the existence of a crown ether.

The synthesis and structural, magnetic and thermal characterization of two pyrophosphate-bridged dinuclear species of {[[[(phen).sub.2]Ni]].sub.2]([mu]-[P.sub.2][O.sub.7])}.27[H.sub.2]O and {[[[(phen).sub.2]Mn].sub.2]([mu]-[[P.sub.2][O.sub.7])}.13[H.sub.2]O are described. It is shown that these two complexes have crystallized with a high degree of hydration and an ornate set of channels have run through the structure.

The homo-and heterometallic coordination compounds with hexa- and pentanuclear formula exhibit oxamato bridges between the units of copper. The substitution of peripheral copper units with nickel ions gives heterometallic complexes with large magnetic spins.

The structural and magnetic properties of layered copper(II) coordination polymers intercalating s-, p- and f-block metal ion nitrates are characterized by X-ray single crystal and powder diffraction methods and thermal analysis. The coupling of diffraction analyses on a few monocrystals have disclosed the structural rules governing the inclusion processes, which is traced back to the photophysical properties of the distinct guest metal ions.

The synthesis, structure and magnetic properties of a giant heterometallic [Cu.sup.I.sub.4][Cu.sup.II.sub.13][Mn.sup.II.sub.4][Mn.sup.IV.sub.12] cluster are presented. An approach is brought about to generate this cluster which contains an unprecedented adamantine-like [Mn.sub.28] core connected wholly by [Mn.sub.4][O.sub.4] cubane units and exhibits unusual magnetic properties.

The synthesis, crystal structures, and magnetic properties of seven complexes derived from [[Mn(SB)].sup.+] and [[Fe(1-c[H.sub.3]im)[(CN).sub.5].sup.2.-] are reported. The ferromagnetic or antiferromagnetic Mn(III)-Fe(III) coupling are attributed to the bending of the Mn-N=C-Fe linkage and the nonplanarity of the xz planes of Mn(III) and Fe(III).

The syntheses, crystal structures, and magnetic properties of four one-dimensional cyanobridged heterobimetallic chain complexes are presented. Complexes [(TP)2[Fe.sub.2.sup.III](CN)6Cu(CH3OH).2CH3OH]n and [(TP)2[Fe.sub.2.sup.III](CN)6Cu(DMF).DMF]n ( Tp=tris(pyrazolyl)hydroborate ) show single chain magnets behavior.

The synthesis and characterization of a new hexanuclear Co complex and a structurally novel one-dimensional coordination polymer composed of alternating hepta- and mononuclear Co-containing fragments are presented. Magnetic studies of these complexes have provided useful insights into the complex interplay between single-ion properties and exchange interactions in polynuclear [Co.sup.II] complexes.

The synthesis, crystal structures, and magnetic properties of a dinuclear complex [[Mn(5-Clsalen)-(N3)].sub.2] with phenoxide bridges and a one-dimensional chain [[Mn(5-Brsalen)(N3)].sub.n] linked by azide a single end-to-end fashion is reported. It is observed that compound [[Mn(5-Brsalen)(N3)].sub.n] exhibits the coexistence of spin canting and metamagnetism, marking a rare example among the azide-bridged one-dimensional systems.

The magnetic properties of the assemblies, dependent on monocation A (A = [Li.sup.+], [Na.sup.+], [K.sup.+], [Rb.sup.+], [Cs.sup.+], [NH.[sub.4].sup.+] is discussed and pathways for ferromagnetic exchange between [Ni.sup.II] and [Fe.sup.III] or [Cr.sup.III] are demonstrated. Variation of A monocations, used for charge neutralization, does not lead to changes in the over-all geometry of {M-CN-Ni(L)} building blocks.

The synthesis, X-ray structure, magnetic properties and successive preliminary density functional theory analysis of azido-bridged binuclear [Cu.sup.II] complex [[Cu.sub.2]([[[mu].sub.1.1-][N.sub.3]).sub.2][(im-2py).sub.2][([N.sub.3]).sub.2] is reported. A large metal-nitroxide ferromagnetic exchange coupling was noticed whose magnitude compares well with that reported for closely related complexes.

The preparation, the X-ray powder diffraction structural characterization and the thermal, optical and magnetic properties of the analogous three-dimensional species, assembled by employing the 5-substituted halopyrimidinolates is reported. The steric demand of these subsituents is accountable for slight perturbance of crystal cell parameters but not for a change in either the coordination of metal center or the overall framework topology.

The first non-heme dinuclear iron(III) complex with an unsupported hydroxo bridge is synthesized and structurally and magnetically characterized. The J value is in excellent agreement with the density functional theory result (J = 46 [cm.sup.-] and is considerably smaller than the coupling reported for diiron(III) complexes with an unsupported oxo bridge (J approximately equal to 200 [cm.sup.-]).

The first heterospin complex is synthesized from polynuclear Ni(II) trimethylacetates and nitronyl nitroxides. Analysis of the set of structural data revealed certain topological relationship within the family of polynulear Ni(II) trimethylacetates.

The synthesis, structure, and magnetic properties of the metal-organic coordination polymer Mn(hfipbb)py[([H.sub.2]O).sub.0.5], composed of interesting Mn chains are reported. Study on the magnetic properties revealed an antiferromagnetic ground state for this network and a field-induced [Mn.sup.2+] moment reorientation.

One dense and two open chiral metal-organic frameworks is presented. Analyses show that the porous framework of {[Ni(sub 4)(2,2',3,3'-odpa)(sub 2-)(bpy)(sub 4)(H(sub 2)O)(sub 4)].(H(sub 2)O)(sub 18} is stable after the removal of solvent water molecules.

A new three dimensional azido-bridged coordination polymer, [Co(sub1.5)(N(sub 3))(OH)-(Isonic)](sub n) is synthesized and characterized and its magnetic properties studied. Isonicotinate acts as a bridging coligand in this complex.

The synthesis, spectroscopic, and magnetic characterization of two early metal di- and tricyanometalates and an S= 4 cluster is described. This is the first well-defined six-coordinate mononuclear cyanovanadate(III) complex.

The syntheses, structural characterization, and magnetic behavior of five new 2D manganese(II) complexes with empirical formulas are reported. The 2D compounds [Mn(N(sub 3))(sub 2)(2,6-DiMepyz)(H(sub 2)O)](sub n), [Mn(N(sub 3)(sub 2)(Etpyz)(H(sub 2)O)](sub n), [Mn(N(sub 3))(sub 2)(H(sub 2)O)(sub 2)](sub n)(2,3-DiMepyz)(sub n) show square layer topology but with the novelty to incorporate water as axial ligand.

The magnetic and magnetic circular dichroism investigations of a binuclear Co(II) compound are reported. The Hamiltonian of the system involves an isotropic exchange interaction dealing with the real spins of cobalt(II) ions, spin-orbit coupling, and a low-symmetry crystal field acting within the (super 4)T(sub 1g) ground manifold of each cobalt ion.

The crystal structure, magnetic properties, and 57Fe Mossbauer spectroscopy of the two-dimensional coordination polymers [M(1,2-bis(1,2,4-triazol-4-yl)ethane)2(NCS)2] are discussed. [Fe(btre)2(NCS)2] is found to retain a HS ground state upon cooling from 293 K to 8 K.

The crystal structures of [MnTPP] {Ni[S(sub 2)C(sub 2)H(CN)](sub 2)} [MnTPP=(meso-tetraphenylporphinato)manganese(III)] and [MnTPP] {Ni[S(sub 2)C(sub 2)(CN)(sub 2)](sub 2)} were determined. These salts possessed trans-mu-coordination of S=1/2 {Ni[S(sub 2)C(sub 2)H(CN)](sub 2)}(super .-) and Ni[S(sub 2)C(sub 2)(CN)(sub 2)](sub 2)}(super .-) to Mn(III) and form parallel 1-D coordination polymer chains exhibiting nu(sub CN) at 2210, 2200, 2220 and 2212/cm, respectively.

The synthesis, structures, and magnetic properties of four cyano-bridged M(super II)Ru(super III)(sub 2) compounds prepared from the paramagnetic Ru(super III) building blocks, trans-[Ru(salen)(CN)2](super -) and trans-[Ru(acac)2(CN)2](super -) are described. The use of trans-[Ru(acac)2(CN)2](super -) and trans-[Ru(salen)-(CN)2](super -) as building blocks has produced a number of trinuclear, 2-D, and 3-D M(super II)Ru2(super III) compounds.

Three new homo- and heterometallic hexanuclear complexes [Mn2M(sub 4)(super II)O2(PhCOO)(sub 10)(DMF)(sub 4)] (with M = Mn, Co, or Ni and DMF = dimethylformamide) are synthesized by redox generation of benzoate ligands from benzaldehyde in a one-pot reaction. Their crystal structures and magnetic properties are investigated and the single-crystal magnetic measurements of [Mn(sub 2)(super III)M(sub 4)(super II)O2(PhCOO)(sub 10)(Ch3CH)(sub 4)] (4) are presented.

The effects of double substitution of Ti and Al for Fe on the structural and magnetic properties of Nd2Fe(sub 17-x-y)Ti(sub x)Al(sub y) compounds are examined. Rietveld analyses of x-ray and neutron diffractions reveal that all the samples crystallize in the rhombohedral Th2Zn17-type structure and the effects of Ti and Al substitutions on the bond lengths in the doubly substituted compounds are different from that in a singly substituted compounds.