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A stoichiometric system in which changes of a metallaborane is mediated by insertion of two alkynes into an irdaborane framework through a disposable molybdenum chaperone carbonyl fragment is presented. The complete procedure, 1+2alkyne= 8+B [H.sub.3]+2[H.sub.2], promoted by (arene)(Mo)[(CO).sub.3], serves as an example of a transition-metal-facilitated process analogous to metal-facilitated organic transformations seen in organometallic chemistry.

The preparation of novel bis([beta]-diketones) linked by 2,2'-biphenyldiyl, 2,2'-tolandiyl, and 2,2'-bis(methylene)biphenyl moieties is presented. The observation showed only a single relative configuration of the biphenyl and bis(chelate) titanium moieties established by crystallography of ([super t][Bu.sub.2]Bob)Ti[(O-2,6-[Pr2C6H3]).sub.2] to be the (R)-LAMBDA/(S)-DELTA diastereomer.

The synthesis and characterization of low-spin (2-methylimidazole)(octaethylporphyrinato)iron(III) chloride (perp-[Fe(OEP)[(2-MeHIm).sub.2]]Cl) is presented. A one-dimension hydrogen-bond is formed between chloride anions and uncoordinated imidazole nitrogen atoms and Mossbauer spectroscopy has verified the low-spin state of the species and confirmed that it is a type I low-spin species with ground state [([d.sub.xy]).sup.2][([d.sub.xz],[d.sub.yz]).sup.3].

The compositions of (E)-1 and (Z)-1 are confirmed by solution NMR studies and also by crystallographic characterization in the solid state. Rate studies using UV-vis spectroscopy reveal the rapid and complete formation of a reaction intermediate between the ketone and magnesium which undergoes first order decay with rate constants independent of the concentration of excess magnesium bis(hexamethyldisilazide, [Mg(HMDS).sub.2] ([delta]H/=17.2 [plusmn] 0.8kcal/mol, [delta]S = -11+3cal/molxK).

Boron-dipyrrin chromophores containing a 5-aryl group with or without internal steric hindrance toward aryl rotation was synthesized and then characterized via X-ray diffraction, static and time-resolved optical spectroscopy, and theory. It is revealed that the critical role of aryl-ring rotation in governing the excited state dynamics and fluorescence properties of the dyes and the result should facilitate the further use of these class of dyes and related systems as optical probes in the life science.

Comparison of the switching signals from the Fe(super III)-Ru(super II) cell [C][X] to that of the Ru(super III)-Ru(super II) cell with larger d1/d(sub m)[PF6](sub 3) shows that increasing the length of the conjugated linker between the metal sites can increase the dipolar switching field. A simple electrostatic model suggests that the smaller is the counterion, the greater is the perturbation of the metal sites and the larger is the barrier for switching.

The synthesis of a low-spin six-coordinate iron(II) porphyrinate in which the two axial ligands arte forced to have a relative perpendicular orientation is successfully accomplished for the first time. The quadruple splitting value is significantly larger than that found for low-spin iron(II) derivates with relative parallel orientations for the two axial ligands and mossbauer spectra thus provide a probe for ligand orientation when structural data are otherwise not available.

Research has been conducted on [Ni(diphosphine) (sub)2] (super)2+ complexes. The preparation of these complexes which contain ligand-appended nitrogen bases is described.

Research has been conducted on the air-stable deep-red complexes. The preparation of these complexes carried out via the stoichiometric reactions of Pt(dibenzylideneacetone) (sub)2 or Pd (sub)2 (dibenzylideneacetone) (sub)3 .CHCl (sub)3 with 2,9-bis-(diphenylphosphino)-1,10-phenanthroline and a single elemental mercury drop in refluxing dichloromethane under nitrogen atmosphere is described.

Research has been conducted on the 1,3,5- and 1,2,4,5-substituted benzene derivatives with long rigid arms. The convergent synthesis of these derivatives involving copper-free Pd-mediated terminal acetylene coupling to aryl halides is described.

The major objective of the study is to demonstrate the comprehensive thermodynamic schemes that can be developed for transition metal-dihydride systems. It may be possible to obtain detailed thermodynamic descriptions of the metal-hydrogen bond in a variety of metal-hydride complexes with nonliable ligands including polyhydride and polynuclear systems.

An unprecedented rearrangement of the framework of the bilindione that occurs as a direct consequence of the pi-coordination of the palladium is reported. This process involves the cleavage of the Pd-Pd and Pd-C bonds, oxidation of palladium, migration of nitrogen atom form one carbon to another and introduction of an oxygen atom (from water) not necessarily in this particular sequence.

Addition of copper(II) acetate to octaethyl(meso-hydroxy)porphyrin ([H.sub.2]OEPOH) in THF under a dinitrogen atmosphere produces [Cu.sup. II](OEPOH), which has been isolated as red crystals and shown to have a meso-hydroxyporphyrin structure by UV-vis and EPR spectroscopy. [Cu.sup.II](OEPOH) undergoes oxidation by dioxygen to form a novel dinuclear copper complex {[Cu.sup.II](OEPOC(O)OEB)[Cu.sup.II]}. This dinuclear complex is composed of a copper(II) meso-substituted porphyrin portion (with a planar Cu[N.sub.4] unit), which is attached through an ester linkage to a helical copper(II) tetrapyrrole that has been ring-opened through oxidative cleavage of a second molecule of [Cu.sup.II](OEPOH). The oxidative ring-opening reaction resembles that of natural heme catabolism but is arrested at a stage where the oxidized meso-carbon is still appended to the helical open tetrapyrrole. A mechanism is suggested for this process. Key words: copper porphyrin, crystal structure, porphyrin oxidation, linear tetrapyrrole, hydroxy-porphyrin, oxophlorin.

Pt(O)/Pd(O) metallocryptates encapsulating Ti(I) were constructed using phosphineimine ligands.

Research has been conducted on the charge-transfer salts. The structural and magnetic properties of these salts have been investigated.

The cocrystallization of fullerene compounds with the metal complexes of octaethylporphyrin is investigated by single-crystal X-ray diffraction. Although fullerenes are known to have a great propensity for disorder, results show that the fullerenes in some of the resulting compounds are ordered. It is also observed that the eight ethyl groups of each metalloporphyrin are arranged in a way that they form an octopus-like embrace of the fullerene surface.

Cyclic bis(trimethylsilyl) enol ethers have been synthesized from cycloalkanone carboxylates. The Lewis acid-promoted (3+4) and (3+5) annulation reactions of these bis(dinucleophilic) synthons with a variety of 1,4- and 1,5-dicarbonyl electrophiles led to the formation of tricyclic keto ethers with good regio- and stereochemical control. The annulated product has an interesting trans intrabridgehead stereochemistry that resembles the ingenol BC ring system.

The synthesis and structural characterization of novel tetranuclear and octanuclear iron(III) complexes were described. The structures of the iron(III) complexes are based on an almost square arrangement of four iron ions. The tetranuclear iron complex (Fe4(mu-O)2(mu-BMDP)2-(mu-OAc)2)(super 4+) is formed by reacting ferric nitrate, sodium acetate and the unsymmetrical binucleating ligand HBMDP. The tetranuclear iron complex was found to have coordination number asymmetry.

Demethylation of (octamethoxyphthalocyaninato)nickel(II) was done to prepare (2,3,9,10,16,17,23,24-octahydroxyphthalocyaninato)nickel(II) (NiPc(OH)8). NiPc(OH)8 was treated with Tp(super Cum,Me)Zn(OH) to investigate the coordination properties of peripheral catechol sites. Broadened proton NMR resonances for arms of the Tp(super Cum,Me) ligands point to a chelated structure for the Zn atoms of (NMe4)4(NiPc(O2ZnTp(super Cum,Me))4).

The annulation/silylation reactions involving 1,5-dienes and 1,6-dienes mediated by an organoyttrium catalyst are described. These afford carbobicyclics in high yields and superior selectivities. An examination of various alkenyl-substituted cyclopentane and cyclohexane substrates reveals that the high diastereoselectivities appear to be due to a preference for a chairlike transition structure. The high selectivity of acyclic triene precursors is similarly traced to a chairlike transition structure.

The bicyclo(1.1.1)pentane cage with penta- or hexafluorinated bridges was observed to be extremely highly strained. It has very closed spaced nonbonded flourines and an increased bridgehead-to-bridgehead separation relative to the parent cage. It was found to be susceptible to reductive C-C bond cleavage and has interesting stereospecific nuclear magnetic resonance coupling constants and 19F chemical shifts. It also has a large acidifying effect on a bridgehead carboxyl.

The gentle thermolysis of the trans-bis(ethylenesulfido)[(octaethylporphyrinato)ruthenium(II)] complex led to the formation of a sulfur-atom-bridged dimer. The resulting compound exhibited a molecular structure of (mu-sulfido)bis[(octahethylprophyrinato)ruthenium(III)]. Furthermore, the compound exhibited a novel unsupported sulfur atom bridge that was located between two atom centers.

An approach to a two-dimensional grid polymer was proposed. Pd-catalyzed coupling of copper with iodobenzene, m-diiodobenzene, and 1,3,5-triiodobenzene yielded 1,12-dicarba-closo-dodecarboran-1-ylbenzene, m-bis benzene and 1,3,5-tris benzene, respectively. Stable dimeric structures were produced from 1,12-dicarba-closo-dodecarboran-1-yl benzene and m-bis benzene through linear coupling of carboranyl CH terminal through a mercury atom. Slow treatment with THF solution removed tentacles of the species.

The thermal chemistry and photochemistry of trans-2,3-diphenyloxirane were analyzed during the photolysis of trans-2,3-diphenyloxirane (TDPO) in cyclohexane. The reaction involved the 1,3-dipolarophilic addition of maleic anhydride and fumaronitrile with the trans-ylide formed by the photolysis of TDPO. The synthetic process also involved combination of fumaronitrile and the trans-ylide intermediate to form cis-2,3-diphenyloxirane.

High diastereoselection in a samarium(II) iodide-promoted ketyl-olefin cyclization reaction was attained by employing tartramide-derived keto allylic acetals as chiral auxiliaries. The remarkable features of the reaction include the fact that remote diastereoselection is attained in a radical process and that high levels of stereochemical induction are seen at both new stereocenters formed in the transformation. This transformation provides the first example of the application of a chelating metal to affect high levels of remote asymmetric induction in a radical reaction.

High-spin, five-coordinate iron(III) dioxoporphodimethene complexes are produced by the insertion of iron(III) bromide to a mixture composed of isomeric forms of free base dioxoporphodimethene and tetrahydrofuran. The compounds caused large downfield shifts of the meso and methylene resonances due to paramagnetic interactions. The trans isomeric dioxoporphodimethene is more symmetric than the cis isomer. The isomers also exhibit meso resonances that are shifted from 30-40 ppm downfield.

The crystallization of solids that are composed of several combinations of inorganic halides were analyzed after reacting with Pd6Cl2 and aromatic hydrocarbons. The polymorphic alpha-form PdCl2 have infinite and linear chains of palladium units that are coordinated by four chlorine atoms with double bridges. The beta-form of PdCl12 is isomorphic with discrete molecules of Pd6Cl12. Pd6Cl12 has a similar geometric configuration to Pt6Cl12 and related transition metal clusters that possess an octahedral array of metal atoms with twelve edge-bridging halogen atoms.

The reactions between C60O and Vaska type iridium complexes were examined. The results showed that reaction with Ir(CO)Cl P(C6H5)3(sub 2) has resulted in partial deoxygenation of the fullerene epoxide. Reaction with Ir(CO)Cl As(C6H5)3(sub 2) has resulted in the formation of crystalline (mu2-C60O)Ir(CO)Cl(AsPh3)2.482C6H6-0.18CHCl3 with the oxygen atom disordered over four positions.

Reaction of Vaska-type iridium complexes with C60 results in two double addition products. X-ray crystallographic studies show that the added groups have 'para' orientation. Spectroscopic studies reveal the elongation of the fullerene along the Ir-Ir axis. 31P(1H) NMR analysis indicates the dissociation of adducts at room temperature, resulting in the formation of regioisomers. These para regioisomers are preferentially crystallized due to their low solubility in benzene.

Spectroscopic and X-ray diffraction experiments help characterize three complexes of cobalt and manganese with the octaethylbiindione ligand. In cobalt complex, four pyrrole nitrogen atoms of the helical ligand surround a cobalt ion exhibiting planar coordination. Temperature-dependent NMR spectrum suggests thermal population of low-lying paramagnetic state in the complex. Magnetic susceptibility studies of a dimeric five-coordinate Mn(III) complex reveal a high spin d4Mn(III). These dimers in pyridine solution undergo cleavage producing monomeric five-coordinate complex, and the Mn in this complex exhibits coordination with four pyrrole nitrogen and one pyridine ligand.

Analyses of the oxidation of iron oxophlorin (meso-hydroxyporphyrin) complexes formed the basis to explore the basic chemical reactivity involved in the heme destruction which the heme oxygenase catalyzes. A pair of novel, extremely oxidized complexes, BrFeIII(OEPO.) and Br2FeIII(OEPOx), result from the reaction of iron(III) octaethyloxophlorin dimer (FeIII(OEPO))2 with molecular bromine. The ligand, and not the iron, experiences the oxidation.

The nickel(II) complex of octaethyloxophlorin NiII(OEPOH) is characterized to study its oxidation in pyridine solution, which generates (py)2Ni(OEPO.). Red, air-sensitive solutions with the diamagnetic and consequently planar four-coordinate Ni(II), result from the dissolution of this complex in pyridine. Chemical experiments prove that dioxygen converts the nickel oxophlorin radical into a mixture of NiII(trans-OEPO2) and NiII(cis-OEPO2).

An iron biliverdin-type complex that is formed with verdohemochrome during coupled oxidation of Fe(II) octaethylporphyrin, was isolated and characterized. 50% diamagnetic((octaethyloxaporphyrin)FeII(py)2)Cl, a verdoheme, and 32% paramagnetic((OEB)FeIII)2 result from the treatment of (octaethyloxaprophyrin)-FeII(py2) with air and ascorbic acid in pyridine solution. H NMR and X-ray crystallographic analysis were used to elucidate dimeric((OEB)FeIII)2.

The preparation of a set of heterobinuclear d6/d8 molybdenum(0)/Palladium(II) complexes is accomplished by the interaction of (t-BuNC)2PdCl2 with mer-Mo(dpm-P, P') (dpm-P)(Co)3, where dpm refers to (bis-(diphenylphosphino) methane). This reaction occurs through the ring opening of the strained, four-membered chelate ring and transfer of an isocyanids ligand to the open coordination site on molybdenum. The two free phosphorus atoms of the dpm ligands entrap palladium to give rise to a (t-BuNc)(OC)3Mo(micro-dpm)2Pd unit.

The cyano complex (OEOP)FeIII(CN)2.1. 6CH2Cl2 containing the low-spin six-coordinate octaethyloxoporphyrin (OEOP) anion is prepared by treating a high-spin six-coordinate (OEOP)FeIIICl2 with bis(triphenylphosphine)nitrogen(1+) cyanide which contains a strong ligand. Crystallographic studies show that the complex forms in the monoclinic space group P2(sub 1)/c with the six-coordinate iron positioned at the center of symmetry. In addition, results of magnetic moment and spectral analyses establish the low-spin character of the complex.

The synthesis of two verdoheme compounds, dianion of octaethylporphyrin and monoanion of octaethyloxophorphyrin is reported. Both derivatives have been characterized by hydrogen nuclear magnetic resonance spectroscopy and x-ray crystallography for identification of the spin, oxidation and ligation states of iron. Findings show that the iron (II) and iron (III) verdohemes consist of planar, tetradentate oxoporphyrin macrocycle structure.

The reaction between mer-Mo(dpm-P,P')(dpm-P)(CO)3 and Ph3PAuCl, where dpm = bis((diphenylphosphino)methane), is investigated. This reaction may form two products and is solvent dependent. The products, which include((OC)3MoCl(mu-dpm)2Au).2(C2H5)2O and ((dpm-O)2Mo(CO)2AuPPh3)(PF6).CH2Cl2.0.25CH3OH.0.25H2O, are binuclear complexes possessing Mo and Au, with the latter possessing a Mo-Au bond. Both complexes contain six-coordinate Mo(0) centers, with the latter having a pair of molybdenum d(sub pi) electrons forming a dative Mo-Au bond.

Iron(III) complexes of octaethyloxophlorin were subjected to H nuclear magnetic resonance and X-ray crystallographic studies. The dimeric (iron III octaethyloxophlorin OEPO)2, which featured two paramagnetic centers, reacted with protic acids to form high-spin, five-coordinate halogenated iron(III) OEPOH complex. In addition, acid/base chemistry examinations revealed that all complexes remained stable in the presence of molecular oxygen.