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The chiral acyclic ligands H2CHXdedpa (N4O2), H2CHXdedpa-bb (N4O2), and H4CHXoctapa (N4O4) (CHX = cyclohexyl/cyclohexane, H2dedpa = 1,2-[[6-carboxy-pyridin-2-yl]-methylamino]ethane, bb = N,N'-dibenzylated, H4octapa = N,N'-bis(6-carboxy-2-pyridylmethyl)-ethylenediamine-N,N'-diacetic acid) were synthesized, complexed with Ga(III) and/or In(III), and evaluated for their potential as chelating agents in radiopharmaceutical applications. The ligands were compared to the previously studied hexadentate H2dedpa and octadentate H4octapa ligands to determine the effect adding a chiral 1R,2R-trans-cyclohexane to replace the ethylenediamine backbone would have on metal complex stability and radiolabeling kinetics. It was found that [Ga(CHXdedpa)](+) showed very similar properties to those of [Ga(dedpa)](+), with only one isomer in solution observed by NMR spectroscopy, and minimal structural changes in the solid-state X-ray structure. Like [Ga(dedpa)](+), [Ga(CHXdedpa)](+) exhibited exceptionally high thermodynamic stability constants (log KML = 28.11(8)), and the chelate retained the ability to label (67)Ga quantitatively in 10 min at room temperature at ligand concentrations of 1 × 10(-5) M. In vitro kinetic inertness assays demonstrated the [(67)Ga(CHXdedpa)](+) complex to be more stable than [(67)Ga(dedpa)](+) in a human serum competition, with 90.5% and 77.8% of (67)Ga remaining chelate-bound after 2 h, respectively. Preliminary coordination studies of H4CHXoctapa with In(III) demonstrated [In(CHXoctapa)](-) to have an equivalently high thermodynamically stable constant as [In(octapa)](-), with log KML values of 27.16(9) and 26.76(14), respectively. The [(111)In(CHXoctapa)](-) complex showed exceptionally high in vitro kinetic inertness over 120 h in human serum, comparing well with previously reported [(111)In(octapa)](-) values, and an improved stability compared to the current industry "gold standards" 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and diethylenetriaminepentaacetic acid (DTPA). Initial investigations reveal that the chiral acyclic hexadentate H2CHXdedpa and octadentate H4CHXoctapa ligands are ideal candidates for radiopharmaceutical elaboration of gallium or indium isotopes, respectively.

A series of metal-organic frameworks (MOFs) containing manganese centers and oligothiophene dicarboxylate linkers have been synthesized: [Mn(3PhT2DC)(DMF)0.45(H2O)2.55·1.55DMF]n (1), [Mn6(3HT2DC)6(DMF)3(H2O)5·xDMF·yH2O]n (2), [Mn(T3DC)(H2O)2]n (3), [Mn(T3DC)(H2O)1.5]n (4), and [Mn(Ph2T3DC)(DMF)2]n (5) (H23PhT2DC = 3,3'-diphenyl-2,2-bithiophene-5,5'-dicarboxylic acid; H23HT2DC= 3,3'-dihexyl-2,2'-bithiophene-5,5'-dicarboxylic acid; H2T3DC = 2,2':5',2″-terthiophene-5,5″-dicarboxylic acid; H2Ph2T3DC = 3',4'-diphenyl-2,2':5',2″-terthiophene-5,5″-dicarboxylic acid, DMF = N,N-dimethylformamide). Compound 1 exists as a 2D sheet, 2-4 are 3D frameworks, and 5 is a 1D chain. Compounds 3 and 4 are isomers, and 3-5 are the first examples of crystallographically characterized terthiophene coordination polymers. In the case of 1, 2, and 5, the extended structure is sensitive to β substitution of the oligothiophene linkers. Compounds 1-3 and 5 show antiferromagnetic behavior with typical values of g and J, and 3 exhibits a spin canting transition at 40 K.

The reaction of 2,2'-bipyridine (bpy) with monomeric chromium(II) precursors was used to prepare the S = 1 complexes Cr(tBu-acac)2(bpy) (1) and (η(5)-Cp)(η(1)-Cp)Cr(bpy) (3), as well as the S = 2 compound Cr[N(SiMe3)2]2(bpy) (4). The crystallographically determined bond lengths indicate that the bpy ligands in 1 and 3 are best regarded as radical anions, while 4 shows no structural evidence for electron transfer from Cr(II) to the neutral bpy ligand.

The known, green, five-coordinate species trans-RuCl(2)(P-N)(PPh(3)) react with R'SH thiols to give yellow cis-RuCl(2)(P-N)(PPh(3))(R'SH) products (P-N = o-diphenylphosphino-N,N'-dimethylaniline; R' = alkyl). The MeSH and EtSH compounds are structurally characterized, with the former being the first reported for a transition metal-MeSH complex, while the thiol complexes with R' = (n)Pr, (i)Pr, (n)Pn (pentyl), (n)Hx (hexyl), and Bn (benzyl) are synthesized in situ. Other trans-RuX(2)(P-N)(PR(3)) complexes (X = Br, I; R = Ph, p-tolyl) are synthesized, and their H(2)S adducts, of a type reported earlier by our group, are also prepared. Thermodynamic data are presented for the reversible formation of the MeSH and EtSH complexes and the H(2)S analogues. The Ru(II)Cl(2)(P-N)(PPh(3)) complex in solution decomposes under O(2) to form [Ru(III)Cl(P-N)](2)(μ-O)(μ-Cl)(2).

The side-on end-on dinitrogen complex [PhP(CH(2)SiMe(2)NPh)(2)Ta](μ-H)(2)(μ-η(2):η(1)-N(2)) reacts with CS(2) with complete cleavage of both C=S double bonds and the formation of [PhP(CH(2)SiMe(2)NPh)(2)Ta](μ-S)(2)(μ-CH(2)), which has two bridging sulfides and a bridging methylene unit. Further reaction with H(2) produces CH(4) and the disulfide complex.

Indium(III) dimethyl, dihalide, and alkoxy-bridged complexes bearing a chiral diaminophenoxy tridentate ligand [NN(H)O](-) were synthesized. The dimethyl complex (NN(H)O)InMe(2) (1) was unreactive toward ethanol and 2-propanol and only partially reactive toward the more acidic phenol. The dihalide complexes (NN(H)O)InX(2) (X = Cl (3), Br (4), I (5)) reacted with NaOEt to form robust alkoxy-bridged complexes with the formula {[(NN(H)O)InX](2)(mu-X)(mu-OEt)} (X = Cl (6), Br (7), I (8)). The reaction of the alkoxy-bridged complexes with water produced hydroxy-bridged dinuclear indium compounds. The hydroxy-bridged complex bearing a chloride ligand [(NN(H)O)InCl(mu-OH)](2) (9) was significantly more reactive toward dissociation and formation of a pyridine adduct than the iodo analogue [(NN(H)O)InI(mu-OH)](2) (10). All compounds were fully characterized in solution by NMR spectroscopy and in the solid state by single-crystal X-ray diffraction. In addition, DFT calculations were used to help explain the reactivity trends observed.

Spectroscopic, structural, and computational studies of verdazyl radical-ruthenium complexes reveal the verdazyl to be a redox-active and non-innocent ligand. The ensuing delocalization of charge is highly sensitive to the nature of the beta-diketonate co-ligands.

Described herein are the scope and limitations using Tp*Rh(PPh(3))(2) as a catalyst for alkyne hydrothiolation with alkyl thiols. In general, catalytic hydrothiolation proceeds in high yields and with high regioselectivity for a wide range of alkynes and thiols. A variety of functional groups were well-tolerated, including nitriles, amines, halogens, ethers, esters and silanes, although strongly coordinating groups were found to be incompatible with hydrothiolation. Both sterically encumbered alkynes and thiols were successful in hydrothiolation. Electron rich alkynes react more rapidly than electron deficient alkynes. Overall, this hydrothiolation protocol provides convenient access to a variety of functionalized branched alkyl vinyl sulfides.

The Ru(III) metronidazole-maltolato and -ethylmaltolato complexes, trans-[RuL(2)(metro)(2)]CF(3)SO(3) (L=ma (1a) or etma (1b)), have been synthesized and tested for potential anti-tumour activity against the human breast cancer cell line MDA-MB-435S using a so-called MTT assay in phosphate-buffered saline; ma=3-hydroxy-2-methylpyran-4-onato, etma=2-ethyl-3-hydroxypyran-4-onato, metro=2-methyl-5-nitro-1H-imidazole-1-ethanol (metronidazole); MTT=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The complexes exhibit lower IC(50) values than our previously reported Ru(III) tris-maltolato and -ethylmaltolato complexes [D.C. Kennedy, A. Wu, B.O. Patrick, B.R. James, Inorg. Chem. 44 (2005) 6529-6535]. An improved synthetic route to the 2-nitroimidazole EF5 (2-(2-nitro-1-H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide) is reported, as well as a related synthesis of a 3-nitro-1,2,4-triazole derivative of EF5, triF5 (2-(3-nitro-1-H-triazol-1-yl)-N-(2,2,3,3,3- pentafluoropropyl)acetamide). The complexes [RuL(2)(EF5)(2)]CF(3)SO(3) (4a and 4b) and [Ru(ma)(2)(triF5)(2)]CF(3)SO(3) (5) were prepared from the [RuL(2)(EtOH)(2)]CF(3)SO(3) complexes (3a and 3b); IC(50) values for 3-5 are high. Data on the uptake of Ru by the cells are also reported. The complexes were characterized generally by all or some of the following methods: elemental analyses, NMR, IR and mass spectroscopies, conductivity, and cyclic voltammetry; complexes 1a and 1b were also analyzed by X-ray crystallography.

Gallium and indium complexes with pendant carbohydrates have been prepared and examined for their potential as radiopharmaceuticals. Carbohydrate-bearing 3-hydroxy-4-pyridinone ligand precursors and their tris(ligand)gallium(III) and -indium(III) complexes were synthesized and characterized by mass spectrometry, elemental analysis, and (1)H and (13)C NMR spectroscopy, and in the case of one intermediate, by X-ray crystallography. With three equivalents of ligand, neutral complexes formed with the bidentate hydroxypyridinone moiety complexing the gallium(III) and indium(III) metal centers.

The reduction of high oxidation state metal complexes in the presence of molecular nitrogen is one of the most common methods to synthesize a dinitrogen complex. However, the presence of strong reducing agents combined with the poor binding ability of N2 can lead to unanticipated outcomes. For example, the reduction of [NPN]ZrCl2(THF) (where NPN = PhP(CH2SiMe2NPh)2) with KC8 under N2 leads to the formation of the side-on bridged dinuclear dinitrogen complex ([NPN]Zr(THF))2(mu-eta2:eta2-N2) with an N-N bond distance of 1.503(3) A; however, reduction of the corresponding titanium precursor, [NPN]TiCl2, under N2 does not generate a dinitrogen complex, rather the bis(phosphinimide) derivative, ([N(PN)N]Ti)2, is isolated in which the added N2 is incorporated between the titanium and phosphine centers. Performing the reaction under 15N2 results in the 15N label being incorporated in the phosphinimide unit. A suggested mechanism for this process involves an initially formed dinitrogen complex being over reduced to generate a species with bridging nitrides that undergoes nucleophilic attack by the coordinated phosphine ligands and formation of the P=N bond of the phosphinimide.

Ru(II) sulfoxide-maltolato complexes, Ru(ma)(2)(L)(2) (L = DMSO (1a) and TMSO (1b) or L(2) = BESE (1c)), were synthesized, as well as the analogous ethylmaltolato derivatives, Ru(etma)(2)(L)(2) (2a-c) (ma = 3-hydroxy-2-methylpyran-4-onate, etma = 2-ethyl-3-hydroxypyran-4-onate, TMSO = tetramethylene sulfoxide, BESE = 1,2-bis(ethylsulfinyl)ethane). A Ru(II) bidentate sulfoxide-metronidazole complex, RuCl(2)(BESE)(metro)(2) (3), was also synthesized (metro = metronidazole = 2-methyl-5-nitroimidazole-1-ethanol). The complexes were characterized generally by (1)H NMR, UV-vis, and IR spectroscopies, as well as MS, elemental analysis, solution conductivity, and cyclic voltammetry. The molecular structures of Ru(ma)(2)(S,R-BESE) (1c) and trans-RuCl(2)(R,R-BESE)(metro)(2) (3) were determined by X-ray crystallography. All sulfoxide ligands are S-bonded. The complexes were tested against human breast cancer cells (MDA-MB-435S) using an in vitro MTT assay, a colorimetric determination of cell viability: 2a,b exhibit the lowest IC(50) values of 190 +/- 10 and 220 +/- 10 microM, respectively. Cisplatin exhibits an IC(50) value of 30 +/- 5 microM.

A series of 2-alkyl-3-hydroxy-4-pyrone oxovanadium(IV) compounds has been synthesized, characterized, and tested for bioactivity as potential insulin-enhancing agents. The vanadyl complexes, bis(maltolato)oxovanadium(IV), BMOV, bis(ethylmaltolato)oxovanadium(IV), BEOV, and bis(isopropylmaltolato)oxovanadium(IV), BIOV, were compared against vanadyl sulfate for glucose-lowering ability, when administered i.p. to STZ-diabetic rats, at a one-time dose of 0.1 mmol kg(-1)body weight. Blood levels of vanadium were determined at regular intervals, to 72 h, following i.p. injection. All complexes tested exceeded vanadyl sulfate in glucose-lowering ability; this effect was not correlated, however, with blood vanadium levels. Analysis of the pharmacokinetics of the disappearance of [ethyl-1-(14)C]BEOV after an oral gavage dose (50 mg kg(-1), 0.144 mmol kg(-1), in a 10 mL kg(-1) volume of 1% CMC solution) indicated clearly that metal ion-ligand dissociation took place relatively soon after oral ingestion of the complex. Half-lives of fast phase uptake and slow phase disappearance for (14)C and V were calculated from a two-compartment model for whole blood, plasma, liver, kidney, bone, small intestine, and lung, ranging from 17 min ( t(1/2)alpha for (14)C, liver) to 30 days ( t(1/2)beta for V, bone). Curves of disappearance of plasma and whole blood (14)C and V diverged dramatically within the first hour after administration of the vanadium complex.

A substantial concentration-dependent red shift of the absorption and emission spectra (77 K) of [Ru(bpy)(2)(POMe-P,O)](2+) (1) (POMe = (2-methoxyphenyl)diphenylphosphine) is reported. NMR experiments show this shift to be due to equilibration of 1 with an aquo complex (1b) (K(eff) = (6 +/- 3) x 10(-3)) that forms upon displacement of the coordinated ether in the hemilabile POMe ligand. The excited-state lifetimes of 1 and 1b at 77 K in solid 2:1 ethanol/acetone solution are tau = 2.13 +/- 0.02 and 1.95 +/- 0.02 mus, respectively. The preparation and X-ray crystal structure of a related complex, [Ru(bpy)(2)(PO(i)Pr-P)(OH(2))](PF(6))(2) (2b) (PO(i)Pr-P = (2-(2-propoxy)phenyl)diphenylphosphine), is also reported. In solution, this species exists as an equilibrium mixture of complexes that cannot be readily separated. This species also has concentration-dependent absorption spectra in 2:1 ethanol/acetone solution, with a significant red shift (20 nm) at lower concentrations.

A number of Re complexes with N,N'-bis(2-pyridylmethyl)ethylenediamine (H2pmen) have been made from [NH4][ReO4]. [ReOCl2(H2pmen)]Cl, [ReOCl(Hpmen)][ReO4], and [ReO2(H2pmen)][ReO4] are related by hydrolysis/HCl substitution. [ReOCl(Hpmen)][ReO4] was structurally characterized and found to contain a water-stable amido-Re bond. Dehydrogenation of the N-donor ligand from each amine to imine with concomitant two-electron reduction of the Re center occurs readily in these systems. With suitable 3-hydroxy-4-pyrones, ternary complexes such as [ReIIICl(ma)(C14H14N4)][ReO4].CH3OH, 5, were made from [NH4][ReO4], H2pmen.4HCl and pyrones in one-pot syntheses. 5, a seven-coordinate ReIII complex, was structurally characterized.

The oxorhenium(V) complexes with ligands containing N4 (H2pmen) and N4O2 (H2bbpen, H2Clbbpen, and H2bped) donor atom sets have been synthesized. X-ray crystallographic analyses of the [ReO(H2pmen)Cl2]+, [ReO(bbpen)]+, and [ReO(bped)]+ complexes showed that all three cations share a rare seven-coordinate structure with a distorted pentagonal bipyramidal geometry, which represents a novel and potentially general structural motif in ReV = O complexes. 1H NMR spectroscopy shows that the structures of the complexes are retained in the solution.