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A series of mixed-ligand 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) rhenium(I) dicarbonyl complexes are synthesized, which includes a new class of the type cis-[Re(CO)(sub 2)(P-P)(N-N)](super +) (where P-P is a chelating diphosphine and N-N is a chelating polypyridine ligand). The properties of these new complexes vary with the net donor ability of the ligands in the coordination sphere and lifetimes and quantum yields of the bipyridine complexes encompass a broad range.

Roles of the biological activity of tropolone, colchicine and antimitotic drugs in synthesis of the metal complexes of the tropolone structures are studied. Antineoplastic behavior displayed by some ruthenium(II) and platinum(II) derivatives is analyzed to show that the antineoplastic behavior showed by the Rh and Pt derivatives is due to presence of the intact complexes. Spectroscopic techniques are used to characterize the metal complexes.

(NEt4)CN displaces vbpy from poly-(Fe(vbpy)3)(PF6)2 thin films in acetonitrile to yield poly-(Fe(vbpy)2(CN)2),poly-vbpy. FT-IR and XPS studies reveal that dicyano films provide a binding site for Ag(+) as AgNO2 to yield poly-(Fe(vbpy)2(CN)(CNAg))(NO2),poly-vbpy. Poly-(Fe(vbpy)3)(PF6)2 incorporates AgNO2 through partitioning. Electrochemical reduction of both films produces colloidal Ag(0). The different negative potentials required for conversion of Ag(+) into Ag(0) reveals different chemical states for Ag(+) in the films.

A solution of HCl reveals the presence of the ground and excited states of trans-NRe(R2-PCH2CH2PR2)2Cl+, which are protonated to form an imido complex, trans-HNRe(R2PCH2CH2PR2)2Cl2+. Various assumed pK values are obtained when the two different states are titrated. The excited state reveals a deep enhancement in basicity due to the titration. The electron density at the nitride nitrogen in the excited state is augmented to cause this modification, which can be represented by a basic orbital diagram.

The reaction of complex cis-(Os(bpy)2(CO)H)+ (bpy = 2,2'-bipyridine) and some related complexes with CO2 in acetonitrile was investigated. The twice- reduced form of the osmium complex was found to be reactive with CO2. Cyclic voltammograms showed a greater current-CO2 concentration proportionality than with H2O. The kinetics of reduction of CO2 by related complexes showed a current increase upon reduction in the bpy wave. Two pathways resulted in the formation of separate intermediates.

The series fac(4,4'-X2-5,5'-Y2-2, 2'-bipyridine)Re(CO)3Etpy(super +) (X = NEt2, Me, OMe, H, Ph, Cl, CO2Me, NO2; Y = H; X = Y = Me; Etpy = 4-ethypyridine) was studied for potential use as catalysts and photosynthesizers. The Re(I) complexes are moderately strong excited-state oxidants and metal-to-ligand charge-transfer (MLCT) excited-state decay is controlled by nonradiative decay from the MLCT state to the ground state. The excited-state properties such as absorption energy, emission energy and rates of nonradiative and radiative decay correlate with theta(sub T).

IR and NMR studies of the rhenium(V) complex (Re(NPh)(O-bpy)(OEt)(PF6))2 reveal a distorted octahedral structure. The oxygen atom of the ethanolate moiety and nitrogen atom of the imidophenyl group form the axial ligands and the 4 nitrogen atoms from the O-bpy ligand form the equatorial ligands. This complex shows electrochemical reversibility, with a negative redox potential. The bonds between Re and N on the open side are shorter.

Axial multiple bonding in the N-Re-OEt structure is responsible for thermal and kinetic stability of trans 2,2'-bipyridine (bpy) ligands in rhenium(V) phenylimido complexes. The unusual stability is noted despite expectedly significant steric interactions between the mutually trans bpy ligands. An X-ray crystal study shows a pseudooctahedral coordination sphere about the rhenium atom, with the bpy ligands twisted in a concerted-canted way. This conformation dampens the steric interactions between the 6 and 6' protons on adjacent bpy ligands.

The reaction of the new precursor cis,trans-Ru(cod)[(anIn).sub.2][Cl.sub.2] with the diphosphine 1,2-bis(diphenylphosphino)-1,2-dicarba-closo-dodecaborane (o-dppc) has unexpectedly resulted in two new ruthenium(II) hydrides. The labeling and reactivity studies have shown that the cod ligand is the source of the hydride.

The preparation of the first metal complexes of triethynylphosphine (TEP) is discussed. TEP was found to be the smallest coordinated phosphines with a cone angle of 103.6 degree and a Re-P bond length of 2.37 Angstrom.

The discovery of luminescence from trans-dioxotechnetium(V) complexes provides the first opportunity to directly compare fundamental luminescence properties of second and third-row d(super 2) metal-oxo congeners. The analytical applications of the TcO2 chromophore offer promise for design of dual mode complexes that can correlate luminescence and radio-imaging properties into a single agent.

Research has been conducted on isomeric ruthenium(II) complexes with dinucleating bis(2-pyridyl)pyrazole ligand. The author report the preparation of these complexes together with Cl nd dmso ligands, and the study of their structural, electrochemical, spectroscopic, catalytic and photochemical properties.

A new type of molecular parallelogram has been prepared based on fac-RE(CO3) corners containing two eta2-alkoxy or hydroxy bridges as one side and 4,4'-bipyridine bridges as the other two sides. The structure of the series of ligand-bridged molecular rectangles has been confirmed by IR, UV, H NMR and elemental analysis. Such structures unusually combine carbon monoxide and alkoxide ligands encircling a RE(I) centre.

Research has been conducted on the oligomeric metal complexes. The single stereospecific photosubstitution of the CO ligand trans to a bridging ligand has been investigated in a symmetric dimeric precursor in preparing the route to liner oligomeric Re(I) polypyridine complexes and the results are discussed.

Results describe preparation of 'linear' oligomers under controlled conditions employing diphosphine bridging ligands and metal-to-ligand charge transfer reactions.

This paper discusses preparation and structural characterization of cyclic diphosphine-bridged oligomers. Results show metal-to-ligand charge transfer in solution resulting in luminescent squares and rings from Re(I)-2,2-bipyridine.

Research was conducted on a new class of long-lived luminescent polypyridine complexes of rhenium(I) with cis-carbonyl ligands. Enhanced stability and red-shifted spectral properties relative to fac-Re(bpy)(CO)3L(+/0) series were observed in the new rhenium excited states. Results also indicate that an energy gap law accounts for the extended lifetimes of the complexes in CH2Cl2 solution.

The synthesis and characterization of the metal complex of N3O4(super -), fac-Re(bpy)(CO3)(N3O4) are presented. The complex has been prepared by the reaction of KN3O4 with the reactive precursor fac-Re(bpy)(CO)3OSO2CF3 at room temperature in water and recrystallized from hexanes/CH2Cl2. Analysis showed that the complex is extremely photosensitive in solution and decomposes to Re(bpy)(CO3)NO3 and N2O.

Reaction of 1,10-phenanthroline 5,6-epoxide (1) with various nucleophiles produces 5-substituted-1,10-phenanthroline ligands. Treatment of 1 with cyanide produces 5-cyano-1,10-phenanthroline, and generates fac-Re(ligand)(CO)3Cl with Re(CO)5Cl in toluene. NMR analysis of fac-Re(ligand 1)(CO)3Cl in CD2Cl2 reveals the fluxional nature of epoxide grouping.

Discusses applications of luminescent transition metal complexes of rhenium(I) in chemical sensing. Ion intercalation into crown ethers covalently linked to luminescent rhenium(I) complexes; Basis for analyzing levels of specific metal ions in solution.

Studies structural and reaction chemistry of multidentate cyclic ligands complexed to rhenium. Synthesis of compounds; Spectral measurement; X-ray structure determination.

Reports on the photochemistry of a structurally uncomplicated phenylcarbyne complex. Carbyne-based photochemical reactions with carbyne derivatives of molybdenum and tungsten; Base-induced quenching process associated with the lowest excited state.

Reports on the synthesis and excited state properties of various trans ruthenium complexes, all of which are synthons for new complexes containing trans metal-to-ligand charge transfer (MLCT) excited states. Ideal precursors for trans oligomers; Trans nature of the dicyano complex.

Reaction of the new precursor cis,trans-Ru(cod)(anln)2Cl2 with the diphosphine 1,2-bis(diphenylphosphino)-1,2-dicarba-closo-dodecaborane (ο-dppc) unexpectedly results in two new ruthenium(II) hydrides, trans-Ru(ο-dppc)2(H)Cl and the neutral, five-coordinate complex Ru(ο-dppc)(nido-dppc)(H), depending upon the reaction conditions [anln is aniline and nido-dppc is 7,8-(Ph2P)2C2B9H10-]. Chloride abstraction from trans-Ru(ο-dppc)2(H)Cl leads to another five-coordinate hydride, [Ru(ο-dppc)2(H)]+, which is isolated as either a triflate or hexafluorophosphate salt. On the basis of labeling and reactivity studies, the source of the hydride appears to be the cod ligand. [ABSTRACT FROM AUTHOR]

The article discusses the highly oxidizing excited states of Rhenium and Technetium in transition metal photochemistry property. This potential is a rare species producing extremely oxidizing excited states in the absorption of visible photon, but it is of great use in solar energy conversion applications. Their properties can help interpret the nature of excited state potential surfaces.

The article describes the first instance of room-temperature luminescence for transition metal complexes. The discovery of luminescence from trans-dioxotechnetium(V) complexes provides the first opportunity to directly compare fundamental luminescence properties of second- and third-row d2 metal-oxo congeners. It is significant that despite well-established studies of the reactivity and spectroscopy of technetium (Tc) complexes in several oxidation states, luminescence has yet to be reported for a Tc complex, although there have been reports of Tc(IV)-halide complexes which luminesce at low temperature and only when isolated in a crystalline host matrix.