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The preparation of complexes of the 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl radical bidentate ligand with bis(hexafluoroacetylacetonato)-manganese(II) and with bis(hexafluoroacetylacetonato)copper(II) is presented. The spectroscopic and magnetic properties on comparison to Co(II) complex reveal that these complexes form dimers via intermolecular S..S contacts in the solid state.

The preparation and structural characterization of two matched pairs of bisdithiazolyl and sulfur/selenium radicals ([R.sub.1] = Me, Et and [R.sub.2] = Ph) are described. The differences in conductivity within the isostructural series is interpreted in terms of their relative solid-state bandwidths, which is estimated from Extended Huckel band structure calculations.

The synthetic routes to salts of the 3H-naphthol[1,2-d][1,2,3]dithiazolylium cation and its three selenium-containing variants (SSeN, SeSN, and SeSeN) are described. The most efficient and general method involves the intermediacy of bis-acetylated aminothiolates and aminoselenolates.

A report on the synthesis and structure of the first known aluminoarsenate D4R derivative (tBuAl(mu3-O3AsPH))4 (1) and the bicyclic galloarsenate ((super t)Bu(sub 2)Ga(mu2-O2AsPh))2O (2) is presented. Compound 1 crystallizes in the rhombohedral space group R3 with one-third of the molecule in the asymmetric unit. Compound 2 has a bicyclic Ga2As2O5 core made up of two mu2-OsAsPh groups bridging two distorted tetrahedral gallium centers.

A new septadentate polyimidazole ligand N,N,N',N'-tetrakis((1-methylimidazol -2-yl)methyl)-1,3-diamino-propan-2-ol, is used for preparing two dinuclear copper(II) complexes. Bridging pyrazolate and acetate ligands, and bridging alkoxide ligands exist in the copper(II) complexes. The copper centers have a distorted square pyramidal geometry in one complex and a trigonal bipyramidal coordination mode in the other. Magnetochemical analysis reveals antiferromagnetic coupling in the former complex and ferromagnetic coupling in the later.

The peroxidation of Mo2(mu-S) complexes produce dimolybdosulfoxide Mo2(mu-SO) and dimolybdosulfone Mo2(mu-SO2). X-ray crystallography reveals the presence of pyramidicity and pyramidal sulfur sites in mu-SO bridge. Proton NMR spectra indicate the presence of conformational isomers related with inversion at the thiolate sulfur bridge. The analysis of photolysis reaction provides evidence of a unimolecular extrusion of free SO. The SO bridge is symmetric, whereas the SO2 bridge is perpendicular.

The covalent halosulfide ligands are produced by the reaction of halogens and metallosulfenyl compound. The reaction occurs at the anionic, radical and neutral bridge sulfur sites of the M2S2 core of the metallosulfenyl compound. The derivative of the metallosulfenyl compound with the structural unit can undergo photolysis in fluorescent light. The W2(mu-SBr) product has three bromosulfide bridge ligand. The structure is determined by the analysis of crystallography.

A dinuclear micro-phenolate bis(mu-acetate) diiron(III) complex, Fe2 (BIOMP)(mu-O2CCH32)(ClO4)*H2O, may be synthesized from a septadentate ligand (H3BIOMP). This compound may provide a model of of the active site of purple acid phosphatase. The crystal structure is in the space group P2(sub 1)/n. The two central, weakly ferromagnetic Fe cations are bridged by a phenolate oxygen and two acetate ions, and the facial sites are connected by amine and imidazole pendants. A large cathodic shift is detected for the complex ion system. Two Mossbauer spectra are seen at 295 and 125 K.

Two mixed imidazole tripodal Cu(II) complexes with distorted trigonal bipyramidal geometries are prepared. Both complexes have imidazole donors at the equatorial sites of the trigonal bipyramid and show an average Cu-N amine bond. IR spectral data are compared with those of another copper complex.

A mu-oxo- mu-carboxylato-bridged dimanganese(III) polymidazole complex is synthesized and characterized using electrochemical magnetic and spectroscopic techniques. The complex is a doubly-bridged, discrete, dimeric unit. The complex is characterized as part of a complex structure and also used for and dimanganese core stabilization.

The condensation reactions of the dimolybdosulfenamide Mo2(NTo)2(S2P OEt 2)2S(O2CMe)(SNH2) with (CH3)2CO and RCHO, where R = H, CH3, C(CH3)3 and C6H4CH3, yielded the sulfenimines Mo2(NC6H4CH3)2(S2P OC2H5 2)2(mu-S)(mu-O2CCH3)(Mu-SN-double bond-CRR'). These sulfenimines contained the N-double bond-CRR' unit. Furthermore, the NMR spectra of sulfenimine solutions showed the presence of both sulfur and nitrogen inversion isomers. The structure of the dimolybdosulfenamide contains a bridging SNH2 linkage.

The W(V) complex (W NC6H4CH3 S2P OC2H5 2 mu3-S)4 has a W4S4 core which forms a distorted cube longer in one direction. Two opposite faces are rhombic with WSW angles at an average angle of 74.6 degrees and SWS angles at an average angle of 101.8 degrees. The mixed-metal cluster W2Mo2(NC6H4CH3)4(S2P OC2H5 2)4(mu3-S)4 is formed when the complex is in solution with (Mo NC6H4CH3 S2P OC2H5 2 mu3-S)4. Comparison between the two compounds indicates that they are similar, except for W-W bonds which are longer than Mo-Mo bonds and M-S bonds which are likely to be longer for W than for Mo.

The presence of hydrogen-bonding interaction between lattice water molecules and the oxo bridge of binuclear (mu-oxo)bis(mu-carboxylato)diiron(III) complexes greatly reduces antiferromagnetic exchange interaction. The crystallographic study uses the diiron complex of a polyimidazole ligand as a core model of hemerythrin, a nonheme iron protein. The intermetallic coupling depends on temperature, which feeds energy to and expands the crystal to weaken hydrogen bonding, thus raising the interaction level. Changing the carboxylate bridge from acetate to benzoate creates a lattice that is more open to thermal expansion and contraction.

The synthesis and structural characterization of the first chelating triamido complexes of bismuth and antimony, Bi[N((super t)Bu)SiMe(sub 2)](sub 3)CH and Sb[N((super t)Bu)SiMe(sub 2)](sub 3)CH are reported. The successful synthesis of oxygen- and light-stable Bi[N((super t)Bu)SiMe(sub 2)](sub 3)CH and Sb[N((super t)Bu)SiMe(sub 2)](sub 3)CH demonstrates that the stability of bismuth and antimony triamides can be increased with chelating triamido frameworks.

Monosubstituted (temima)Fe(Cl)OFeCl3 products were synthesized by the reaction of sterically hindered polyimidazole ligand temima with (Et4N)2[Fe2OCl6]9. The monosubstituted (mu-Oxo)diiron(III) complex forms unsymmetrical compounds exhibiting [Fe2O(temima)(L)(OAc)]3+.12 structures by reacting with tetradentate polypodal ligands with NaOAc and NaClO4. Steric interactions between temima and tmima ligands leads to the formation of the unsymmetrical (mu-Oxo)diiron(III) complex with polyimidazole ligands.

X-ray crystallographic analysis facilitates the characterization of a new methane monooxygenase enzyme active site model. The presence of tert-butyl hydroperoxide and oxygen gas increases the alkaline functionalization activity of this enzyme analogue through a terminal H2O ligand. A radical clock substrate experiment shows that this analogue increases the rate of free radical rearrangement of cyclopropylcarbinyl to phenyl-but-3-enyl radical.

A secondary amine HNR1 was removed from a triaminophosphine to form iminophosphine, revealing thermodynamic preference for diaminophosphines. A tetracoordinate phosphorane which exhibits tautomerism mediates the elimination reaction. Under low-coordinate and sterical conditions, co-products promoting thermodynamic elimination reaction cannot aid the production of iminophosphines. Hence, the process of decomposition of phenylaminophosphines due to heat, amine elimination and oligomerization is most viable.

The activation of ligand reactivity was demonstrated in sulfide alkylation, thiolate dealkylation and dithiophosphate de-esterification within molybdenum(V) dimers. The cationic complex of molybdenum was inductively activated toward thiolate C-S and dithiophosphate C-O heterolyses. The de-esterification of the diethyl dithiophosphate ligands yielded complexes containing the rare monoester EtO(O)PS(sub 2)(super 2-) ligand.