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The reaction equilibria involving binding and exchange of the terminal ligands (H2O/C[H3CN/[Cl.sup.-]) in the mononuclear iron(III) and oxo-bridged diiron(III) complexes are studied in order to determine the roles played by exogenous terminal ligands in non-heme iron proteins. The results reveal that the major deterrent for the formation of either a terminal [Fe.sup.III]-OH or the bridging [Fe.sup.III]-OH-[Zn.sup.III] is the dimerization reaction at the [Fe.sup.III]-H2O site leading to the formation of the oxo-bridged compound.

The reactivities of zinc(II) with three tetraiminodiphenol macrocycles [H(sub 4)L(super 1-3)](ClO4)(sub 2) with varying [CH(sub 2)](sub n) lateral chains are studied spectrophotometrically and spectrofluorimetrically. The photoluminescence behavior of a series of para-substituted benzenecarboxylate-bridged complexes [Zn(sub 2)L(super 2)(mu-O(sub 2)CR)](super +) shows that the intensity of luminescence increases with the electron-releasing substitutes.

The structure of the dinuclear copper(II) complex with the composition [Cu2(L3)(ClO4)2] resulting from the transmetalation reaction of a protonated macrocyclic magnesium compound with copper(II) perchlorate in the presence of triethylamine is described. The dinuclear copper(II) shows that the ligand H2L3 is the [2+2] cyclized derivative of 4-methyl-2,6-diformylphenol and 1,2-diamnoethane. It was also observed that in the absence of triethylamine the transmetalation reaction results in a copper-deficient compound.

Research was conducted to investigate the effects of replacing Fe(III) with either Mn(III) or Mn(IV) which are quasi-isostructural but not isoelectronic with the FeIIIMIIFeIII centers. The syntheses and magnetic and spectroscopic properties of the complexes (LMnIII((mu-dmg)3MII)MnIIIL)(ClO4)2 and (LMnIV((mu-dmg)3MII)MnIVL)(ClO4)4 and the crystal structures of MnIIIMnIIMNIII and MnIIICuIIMnIII were analyzed. Results demonstrate that it is possible to stabilize the tris(dimethylglyoximato)metalate(II) tetraanion by complexation with the LMn3+ or LMn4+ unit.

Tetraaminodiphenols macrocyclic ligand was used in the synthesis of a series of heterobimetallic complexes. The magnetic parameters of these complexes are studied. Results indicate that the complexes behave ferromagnetically with the exception of the manganese-based complex. The copper-based complex had the highest ferromagnetic interaction. The exchange coupling constant is well correlated with the angle formed by the metal planes in this complex.

A study was conducted to determine of using chromium(III) as the terminal Mt ions in complexes, which are quasi-isostructural with the FeIIIMIIFeIII and MnIVMIIMNIV. Some of the instruments used were mass spectrometer and electron paramagnetic resonance spectroscopy. Results showed that there are two exchange couplings constants which are operative in the clathrochelates and a formation of uncommon species such as Cu(III), Ni(III), Ni(IV) and Fe(III) was seen.

Syntheses and characteristics of low-valent clusters (X(Co(mu-CO)(PMe3)2)3), X = none (1), H (2), and H3 (3), are shown. The molecular structures of C21H54Co3O3P6 (1) and C21H57Co3O3P6 (3) have central Co3 units which form perfect equilateral triangles. Both compounds crystallize in trigonal space group R3c with Z=6. The temperature-dependent magnetic susceptibility of the compounds suggest paramagnetic characteristics.

The synthesis and characterization of a series of heterobimetallic complexes Fe(III)M(II)L(mu-OAc)(OAc)(H2O)(ClO4).nH20 and Fe(III)Co(III)L(mu-OAc)(OAc)2(mu-O)(ClO4)2.3H2O are described. The scheme uses the dihydroxy-bridged diiron(III) complex FeIII(HL)2(mu-OH)2(ClO4)2 derived from a tetraaminodiphenol macrocyclic ligand as the precursor. The exchange coupling constants for these complexes were obtained.

Use of the (Cu(DopnH))(+) cation, (H2Dopn is 3,9-dimethyl-4,8-diazaundeca-3,8-diene-2,10-dione dioxime) helps synthesize heterodinuclear complexes of the type Cu(II)M, (M is Cr(III), Mn(III), Mn(II), Fe(III), Co(II), Zn(II)). The synthesis reveals the ability of the oximate dianion to act as a bridging ligand and mediate of exchange interactions. Spectroscopic and variable-temperature magnetic susceptibility studies help characterize these complexees. X-ray studies help characterize crystal structures of the sigma nature of the Cu(Dopn)-M interaction.

The synthesis and characterization of the tetranuclear complex (L4Cu4(Im)4)(ClO4)4.2H2O (L = 1,4,7-triazacyclononane; Im = imidazolate anion) was reported. The reaction of (Cu(ImH)2(OAc)2) and cyclic amine in methanol and addition of perchlorate yielded the complex which consisted of a centrosymmetric tetranuclear cation, four noncoordinating perchlorate anions and two water molecules. The magnetic susceptibility, EPR spectra and magnetostructural correlation of the imidazolate-bridged copper(II) complex were also studied.

The synthesis of copper, nickel and cobalt complexes of 6,6'-bis(bromo/chloromethyl)-2,2'-bipyridines structural, electromchemical and photochemical reactivities are studied. The copper complexes show a flattened tetrahedral geometry with [D.sub.2] symmetry and the nickel complexes have a near-perfect geometry.

Syntheses, structures and magnetic properties of one mononuclear inclusion compound [[Cu.sup.III][L.sup.1 [sub set of] ([H.sub.2]O)] and three tetrametal systems derived from the hexadentate Schiff base compartmental ligand N,N'-ethylenebis(3-ethoxysalicylaldimine) ([H.sub.2][L.sub.1]) are described. The observation of a weak interaction is explained in terms of the structural parameters and symmetry of the magnetic orbitals.

A study was conducted to report on the synthesis, structural characterization, stereochemistry, redox activities, and spectroscopic properties of ruthenium complexes of a new bridging ligand 3,5-bis(benzimidazol-2-yl)pyrazole (H3pzbzim). This ligand forms the mononuclear complexes [(L)(sub 2)Ru(H3pzbzim)](super 2+)(L = bpy or phen) in the neutral form and the binuclear complexes [(L)(sub 2)Ru(H2pzbzim)Ru(L)(sub 2)](super 3+) in the monoanionic form after disassociation of the pyrazole NH proton.