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N-acyl 3,4-disubstituted pyrroles are synthesized directly from hydrazine and an aldehyde via a Piloty-Robinson pyrrole synthesis. The free N-H pyrroles are accessed after the Piloty-Robinson reaction and they are used in the synthesis of octaethylprophyrin and octaethyltetraphenylporphyrin.

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].

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.

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.

The species have a nitrogen-donor axial ligand trans to the nitrosyl ligand and display planar as well as highly nonplanar porphyrin core conformation. The solid state Mossbauer parameters, nitrosyl stretching frequencies, and electronic spectra of these cations are consistent with other [Fe(Porph)(L)(NO)](super +) complexes which have relatively planar hemes and linear FeNO groups.

Research has been conducted on the deoxymyoglobin model (2-methylimidazole)(tetraphenylporphinato)iron(II). The preparation and characterization of this model are described and the results of the X-ray structure analysis indicate the presence of distortions in the iron coordination group and in the porphyrin core.

The authors review the publications on interactions of metalloporphyrins with different nitrogen oxides. The topics of interest include the structural aspects of nitrogen oxides with metalloporphyrins.

The study of the synthesis and crystallographic characterization of the five-coordinate iron(III) porphyrinate complex [Fe(OEP)(NO)]ClO4 was reported. The Mossbauer isomer shifts suggest formal oxidation states greater than +3 for iron, but the NO stretching frequencies are not consistent with such large charge transfer to NO.

Research describes structural and magnetic properties of six chiroporphyrins. Results show bond-stretch isomerism exists in the form of hydrogen bonding from an aqua ligand of iron(III) extending to ethanol or water molecule, which may be involved in the regulation of hemoprotein structure and function.

Research is presented describing the study of porphyrinate derivatives to determine intrinsic structural distortions.

Research has been conducted on the formal iron(IV) porphyrinate derivative. The investigation of the derivative's molecular structure has been carried out.

Research has been conducted on the preparation and characterization of the beta-oxochlorin derivative and its pi-cation radical derivative. The use of single-crystal X-ray structure determination is analyzed.

The trinuclear complex (Mo3O4(TPP)3)+, where TPP = dianion of meso-tetraphenylporphyrin, is formed by either the controlled hydrolysis of (MoO(TPP)(OClO3)) or the reaction of (MoO(TPP)(OClO3)) with ((MoO(TPP))2O). It also contains a highly rare linear O=Mo-O-Mo-O-Mo=O linkage. The molecular structures of (Mo3O4(TPP)3)+ and the monomolecular complexes (MoO(TPP)(OClO3)) and (MoO(TPP)(OH2))ClO4 are presented.

The x-ray structures and synthesis of nickel(II) and zinc(II) meso-tetracyclohexylporphyrin H2(TCHP) were described. It was noted that substitution by cyclohexyl groups on the meso positions of a metalloporphyrin has notable stereochemical and electronic effects. The meso-cyclohexyl groups had lower rotation barriers than meso-phenyl groups, despite their greater steric bulk and they imparted easier oxidation and harder reduction to the porphyrin as compared to tetraphenylporphyrin derivatives.

The molecular structure of the pi-cation radicals complexes of 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrinates were been investigated. The x-ray structure of the zim complex indicated a possible alternating bond distance pattern that could result from a pseudo-Jahn-Teller effect of coupled A1u and the A2u electronic states. The copper complex reacted with thianthrenium to produce a beta-thianthrenium derivative. The structure of the thianthrenium derivative and a symmetrically substituted beta-tetraiodo derivative are elucidated.

Research was conducted to examine the synthesis, characterization and structure of various iron(III) nitrosyl porphyrin derivatives using Mossbauer spectroscopy and X-ray structure analysis. Experiments performed on iron(III)(nitro)(nitrosyl) complexes revealed the important role of the pi interaction between the axial ligands and iron. Results demonstrate that the derivatives have a diamagnetic ground state and that there is no evidence for the presence of a thermally accessible paramagnetic excited state.

A family of neutral, urea-appended, free-base porphyrins and their zinc(II) compounds was synthesized and characterized. The (alpha, alpha, alpha, alpha)-5,10,15,20-tetrakis(2-(arylurea)phenyl)porphyrins bind strongly to chloride anion in DMSO-d6 and in more competitive solvent system DMSO-d6/D2O and bromide anion in DMSO-d6. The stoichiometry of binding for porphyrins and anions was analyzed and the enthalpy of complexation was determined. The binding motif includes the halide which is located deep within the porphyrin pocket.

Resonance Raman spectroscopy was used to examine the axial ligation of nickel(II) 5,10,15,20-tetraphenylporphyrin with pyrrolidine or piperidine. The axial ligands and their orientations influenced the type and magnitude of the calculated nonplanar distortion. Narrow and symmetric Raman lines were observed because of the similarity in macrocyclic structural parameters of the conformers and the free rotation of the axial ligands. Analysis revealed the relationship between the orientations of axial ligands and the macrocyclic distortions.

Research was conducted to study the synthesis and spectroscopic characterization of four heterometallic porphyrinate dimers containing rhodium-thallium metal-metal bonds. The reduction of the rhodium(III) derivative was performed under strictly anaerobic conditions and were monitored by UV/visible spectroscopy. Results indicate that the photochemical properties of the (Porph)Rh-Tl(Porph') complexes are extremely complicated in comparison to those of the similar (Porph)Rh-In(Porph') derivatives.

The chloroiron(III) complex of alpha-beta-alpha-beta-tetramethylchiroporphyrin, FeCl(TMCP), was synthesized and structurally characterized. The structure has a unique five-coordinate high-spin iron(III) center in a strongly ruffled and domed porphyrin, with short equatorial distances and the iron 0.64 angstrom out of the porphyrin mean plane toward the chlorine atom. The pyrrole proton resonances are shifted downfield to 80-100 ppm at 293 K, more than in the corresponding tetraaryl derivatives.

The synthesis of the five-coordinate N-bound mono(nitro) iron(III) complex, (Fe(TpivPP)(NO2)) was presented. The electron paramagnetic resonance spectroscopy was utilized to characterize the reaction system of the complex. Results revealed that a five-coordinate of the mono(nitro) iron(III) complex (Fe(TpivPP)(NO2)), which is a low-spin species and is unstable in nature, can be found in the complex. Oxygen atom transfer feature can also be seen the species.

A study was conducted on the chlorocobalt(III) complex of alphaBetaalphaBeta-tetramethylchiroporphyrin, CoCl(TMCP), as a potential enantioselective host or chiral NMR shift reagent for optically active amines. The findings indicate that CoCl(TMCP) may be act as a chiral NMR shift reagent for conformational studies of chiral amines and as an analytical reagent for determining their enantiomer composition.

The structures of three porphyrin species were characterized as their perchlorate salts to examine the effects of changing the peripheral substitution pattern in a class of relatively unstrained porphyrin on systematic conformational changes that reflect an underlying change in the flexibility of the ligand. Different D2d-distortions were observed in all three porphyrin diacid derivatives. It was also seen that all the crystalline forms of the derivatives have core conformations and acute porphyrin-phenyl dihedral angles.

The anionic derivative of bis(azido)(tetraphenylporphinato)ferrate(III) was prepared and characterized using various techniques including crystal structure determination, temperature-dependent infrared spectroscopy and Mossbauer spectroscopy. In an effort to stabilize the six-coordinate anionic porphyrin and solubilize sodium azide crown ether 18C6 was used. A link between a high spin state and high temperature was also established.

Investigations involving the synthesis, structure and thermodynamic characterizations of bispyridine and bis-imidazole complexes of iron (II) tetramesityleporphyrinate were conducted. The ferrocytochrome models including [Fe(TMP)(4-CNPy)2], [Fe(TMP)(3-CNPy)2] and [Fe(TMP)(4-MePy)2] were compared in their solid state with the same complexes in homogeneous solution. Results showed that the thermodynamics of legal binding were not affected by the electronic properties of the axial ligand while low-spin d6 metalloporphyrins preferred parallel orientation of planar axial ligands.

The macrocyclic [CuI/II(bite)]+(bite = biphenyldiimino dithioether) was examined to demonstrate its fully-gated electron transfer and to determine its biological relevance. The research employed a ligand to assist template condensation, EXAFS, X-ray crystallography, electronic and NMR spectroscopy that would determine solution state structures. Results show that small reorganizational processes at copper site do not promote fast electron transfer reactions.

The two crystalline forms of the six-coordinate complex [Fe-(TpivPP)(NO2)(NO)]- synthesis and characterization were investigated. New (porphinato)-iron(II) complexes having nitric oxide and nitrite were examined to determine their bonding and electronic structure. Iron(II) nitrite derivatives starts the syntheses of {FeNO}7 complexes characterized by a combination of spectroscopic methods and X-ray diffraction studies. Results demonstrate the relative importance of the relative effects of axial ligand orientation in defining electronic structure in iron porphyrins.

The solution properties of the metalloporphyrin mixed-valence pi-cation radicals were studied using infrared spectroscopy and computer-aided computation of equilibrium constants. The results revealed that the stability of the metalloporphyrins arises from delocalization of a one-electron hole over two porphyrin rings. It was further demonstrated that the mixed-valence pi-cation radical complexes exhibit novel electronic absorption bands in the near-infrared spectrum which are not observed in either the neutral M(OEP) or the (M(OEP.))+ pi-cation radical derivatives.

The pi-cation radical derivatives such as [Fe(OEP.)(Br)]+ and [Fe(OEP.)(Cl)]ClO4 were analyzed by Mossbauer and infrared spectroscopy to determine the characteristics and magnetic interactions of the compounds. The pi-cation radical derivative, [Fe(OEP.)(Cl)]ClO4 are composed of porphyrin radicals that are strongly coupled to high-spin iron(III) centers. The derivatives exhibited similar intermolecular magnetic coupling but the chloro complex exhibited weaker antiferromagnetic iron-radical coupling.

The synthesis and molecular structure of a new class of pi-cation metalloporphyrin derivatives of the form (M(OEP (sup ./2)))(sup 2+) where M = Ni,Cu,(Zn,H2) were performed. The derivatives, which contain a single electron hole for each pair of porphyrin rings, are prepared by oxidizing one electron equivalent for every pair of porphyrin rings. They exhibit binuclear structures with cofacial and dimeric porphyrin rings.

Isocyanide complexes of (porphyrinato)iron(III) species, ((Porph)-Fe(t-BuNC)2)ClO4, Porph = OEP, TPP, were synthesized and characterized. Consistent with the predicted effect from the strong pi-acceptor character of the axial tert-butyl isocyanide ligands, the X-ray structure of the complex revealed that the porphyrinate ring is strongly ruffled.

(Porphinato)nickel(II) exhibits a strong pi-pi interaction due to a tightly packed dimer configuration that produces a small interplanar separation. The peripheral substituents of Ni(P) exhibits minimal crowding with a planar single crystal in solution compared to other nickel porphyrins. Ni(OEP), Ni(TPP), Ni(UroP8-) and Ni(ProtoP2-) exhibit planar and nonplanar structures in solutions. The units that are larger than hydrogen undergo shifting toward the nonplanar structure for conformational equilibrium. Nonplanar conformations are induced by a slight increase in steric crowding.

Protonation of an oxo-bridged manganese complex or hydrolysis of monomeric manganese complex or monomeric manganese(III) octaethylporphyrinates results in the formation of (mu-hydroxo)bis(octaethylporphinato)manganese (III) perchlorate. X-ray diffraction data shows that each Mn(III) ion is axially coordinated with an Mn-O(H)-Mn bridge angle of 152.73(11) degree. The two porphyrin ring are nearly eclipsed. The Mn(III)...Mn(III) bond interaction in Mn(OEP)2(OH)CLO4 is fairly antiferromagnetic and is controlled by zero field-splitting effect.

A study on the preparation, crystallization, and molecular structure of the redox pair (octaethylporphinato)bis(pentamethylene sulfide)osmium(II) and (octaethylporphinato)bis(pentamethylene sulfide)osmium(III) hexafluorophosphate shows that both complexes have the osmium atom centered in the porphyrin plane with required inversion symmetry. The average OsII-Np =2.050(9)angstrom and the axial OsIII-S distance is 2.352(2) angstrom. The average OsIII-Np is possibly shorter, at 2.046(2) angstrom, and the axial OsIII-S distance is longer, at 2.382(2) angstrom.

The synthesis and characterization of the hydroxo-bridged complex, (mu-hydroxo)bis( tetraphenylprophinato manganese III ) perchlorate, are described. The complex has been prepared by the controlled hydrolysis of monomeric diaquo(tetraphenylporphinato)manganese(III) perchlorate. X-ray structure analysis showed two five-coordinate manganese(III) ions bridged by a single hydroxo ligand.