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This review has tried to collect and correlate all the various equations for the g matrix of strong field d5 systems obtained from different basis sets using full electron and hole formalism calculations. It has corrected mistakes found in the literature and shown how the failure to properly take in symmetry boundary conditions has produced a variety of apparently inconsistent equations in the literature. The review has reexamined the problem of spin-orbit interaction with excited t4e states and finds that the earlier reports that it is zero in octahedral symmetry is not correct. It has shown how redefining what x, y, and z are in the principal coordinate system simplifies, compared to previous methods, the analysis of experimental g values with the equations.

The trans-[RuS[O.sub.4][(N[H.sub.3]).sub.4](L)]Cl complexes, (L = nicotinamide (nia), L-histidine (L-hist), 4-picoline (4-pic), 4-chloropyridine (4-Clpy), isonicotinamide (isn), pyrazine (pyz), 4-aminopyridine (4-N[H.sub.2]py), 4-cyanopyridine (4-CNpy), pyridine (py), imidazole (Him), and water ([H.sub.2]O)), were characterized by elemental analysis cyclic voltammetry, UV-vis, IR, and electron paramagnetic resonance spectroscopies. From the four v (S[O.sup.2-.sub. 4]) observed only [v.sub.3] and [v.sub.4] split in two bands each for the sulfate unidentate coordination. The values of [DELTA]/[xi] parameters, extracted from g values, allow us to write the following order of increasing [pi]-donation ability: pyz < (py, 4-CNpy, 4-Clpy. 4-pic, isn, nia) < Him < L-hist < 4-N[H.sub.2]py. The intense absorption in the 317-347 nm ([epsilon] ~ 2.3-5.6 x [10.sup.3] [M.sup.-1] [cm.sup.-1]) region was tentatively assigned to sulfate-to-metal charge transfer (LMCT) and the absorption in the range of 230-270 nm ([epsilon] ~ 2 - 6 x [10.sup.3] [M.sup.-1] [cm.sup.-]) assigned to an internal (IL) [pi]-[[pi].sup.*] transition in the heterocyclic ligands. The rate for the sulfate aquation in trans-[[RuS[O.sub.4][(N[H.sub.3]).sub.4]L].sup.0] complexes was evaluated through chronopotentiometric measurements and are in the 2.6 [s.sup.-1] (chloropyridine) to 20 [s.sup.-1] (pyrazine) range. The S[O.sup.2-.sub.4] is aquated in trans-[[Ru.sup.III]S[O.sub.4][(N [H.sub.3]).sub.4](4-pic)]Cl at the specific rate constant of (1.4 [+ or -] 0.4) x [10.sup.-5] [s.sup.-1], which is very much slower than in trans-[[Ru.sup.II]S[O.sub.4][(N[H.sub.3]).sub.4](4-pic)] (5.4 [s.sup.-1]). The X-ray crystal structure data show that the Ru--Cl (2.3444(9) [Angstrom]) and Ru--N[H.sub.3] (2.100(2) [Angstrom]) mean distances in trans-[RuCl[(N[H.sub.3]).sub.4](4-pic)][Cl.sub.2]* [H.sub.2]O are similar to the ones observed in other tetraammineruthenium(III) complexes. Key words: ruthenium, sulfate, ammines.

A single-crystal EPR study of [CpTi(NPt-Bu(sub 3)(mu-Cl)](sub 2) permitted the determination of the best-fitted values for the diagonal spin Hamiltonian parameters. This study seems to be the first EPR single-crystal study of a Ti(III) - Ti(III) dimer and the implications of these data are considered and discussed in the light of the extended Huckel molecular orbital calculations.

Mn2+-doped (Fe(bpp)2)(CF3SO3)2*H2O and (Fe(bpp)2)(BF4)2 were studied over a range of temperatures using Mn2+ electron spin resonance (ESR). The changes in the ESR spectra of Mn2+ were examined with temperature and followed with time for a sample in which the metastable high-spin state was generated by rapid cooling. The rate of change from the high-spin phase to the low-spin phase was observed to be the same as that measured for the corresponding spin change derived from magnetic susceptibility and Mossbauer spectroscopy studies.

Deep blue (E=S) or green (E=Se) solutions are produced by the air oxidation of the cluster compounds (Li(sub2)E(NtBu)(sub3)(sub2)) in toluene. The ESR spectra comprises a septet of decuplets and simulations show that secondary hyperfine splitting occurs from interaction of the unpaired electron with equivalent Li ions. Such spectra are assigned to the radion anions SeO(NtBu)(sub2) and SeO(sub2)(NtBu).

Reactions between three groups of substituted o-quinones, 3,5-di-tert-butyl-1,2-benzoquinone (TBQ), 1,2-naphthoquinone, and 9,10-phenanthrenequinone, with an organometallic compound, phenyllithium, were investigated by electron paramagnetic resonance (EPR) spectrometry. The results revealed the formation of M(TBSQ) and the adduct Li(TBSQ)2,2'-bipyridine. There were also evidence for the formation of biphenyl from the oxidation of phenyllithium.

The approximate density functional theory is used in conjunction with spectroscopic and x-ray crystallography measurements to study the thermodynamics associated with the decomposition of HCN2(SPh)3 by free radicals. Results show that the major products of the decomposition process are diazene and PhSSPh. The data also suggest that diazene is formed by a mechanism in which the RS radical acts as the catalyst.

The successive one-electron-transfer reactions of indium(II) iodide with various substituted o-quinones to produce (SQ)InI2 products, where SQ = semiquinone radical anion, have been examined. The results showed that reaction proceeds via attack of the quinone on the solvated In+ cation present in the toluene solutions of In2I4, forming either (SQ)InI2 or (SQ)InI2(picoline)2 as product in subsequent reactions.

The theory of NMR paramagnetic shift of pseudotetraheral Ni(II) and Co(II) complexes uses the atomic overlap method for the ligand field and accounts for the F and the P states. In Co(II) complexes, the d(sub plus or minus 2) orbitals generate the shifts. Observations reveal that the shifts in Ni(II) complexes are susceptible to delocalization of spin from in pi aromatic molecular orbitals (MO). Experimental results indicate that for Ni(II) complexes the contact shift is not isotropic. The Co(II) and Ni(II) complexes of type I exhibit HOMO pi-MO of (+) symmetry for the ligand.

Electron spin resonance spectroscopy and single-crystal x-ray diffraction studies were used to characterize the synthesis and structure of two binuclear iron(II) complexes. Resonances were determined based on the spin-Hamiltonian parameters designated for the compounds. Results consisted of extremely large values, suggesting that there may be errorsin the underlying theory when applied to other compounds.

The synthesis and characterization of Ga(TBSQ.)3 (TBSQ. = 3.5-di-tert- butyl-1,2-benzosemiquinonate anion) was reported. The compound consisted of three TBSQ.- anions coordinated by a gallium atom as analyzed by X-ray crystallography. The EPR spectra and magnetic susceptibility studies of the compound in toluene and other solvents showed evidence of the existence of a triradical and monoradical state.

Five-coordinate complexes of iron(III) and gallium(II) were obtained and characterized by crystallographic, electrochemical and electron paramagnetic resonance methods. The complexes showed enhanced formation of phenoxyl radicals and an improved reversibility of the ligand-centered redox processes was observed suggesting that unusual magnetic interaction between metal and radicals may take place.

The amphiphilic behavior and the molecular structure of cobalt(II)-containing soft-materials with asymmetric tridentate ligands are studied. The complexes are found to exhibit similar amphiphilic, where as different collapse mechanisms.

The design of new molecular scaffolds for multispin complexes based on a novel binucleating ligand, where the coordinated metals exhibit unusual geometries that stabilize radical formation, is described. Well-behaved one-electron oxidations and reductions are needed for precise modulation and switching and might lead to the use of different metal centers and organic groups capable of radical stabilization.

Monometallic species with d(super 5) high-spin iron and d(super 10) gallium were synthesized and studied to assess the influence of the ligand rigidity and the presence of tertiary butyl substituted phenol rings on their steric, electronic and redox behavior. The results showed that the nature/rigidity of the ligand defines whether meridonal or facial coordination would take place.

Research has been conducted on ruthenium and osmium complexes. The synthesis and characterization of these complexes have been carried out via cyclic voltammetry, elemental analysis, and vibrational, electronic, EPR and (super)1H NMR spectroscopies.

The EPR spectra of NO(super .) bonded to Ru(II) in three different complexes were detected in frozen solutions at 77 K. The theory of the EPR spin Hamiltonain of bound NO(super .) is applied to the observed frozen liquid spectra of NO(super .) bound to Ru(II) obtained from Ru(super II)NO(super +) complexes by reduction.