Crystal structure of 1-imidazole-1-methanol.

The synthesis and the crystal structure of 1-imidazole-1-methanol, CHNO, are described. This compound comprises an imidazole ring with a methanol group attached at the 1-position affording an imine nitro-gen atom able to receive a hydrogen bond and an alcohol group able to donate to a hydrogen bond. This imidazole methanol crystallizes with monoclinic (2/) symmetry with three symmetry-unique mol-ecules.

Experimental and Computational Study of the Structure, Steric Properties, and Binding Equilibria of Neopentylphosphine Palladium Complexes.

Steric properties of crystallographically and computationally determined structures of linear palladium(0) and square planar palladium(II) complexes of di(-butyl)neopentylphosphine (P(-Bu)Np), -butyldineopentylphosphine (P(Bu)Np), and trineopentylphosphine (PNp) have been determined. Structures of linear palladium(0) complexes show that steric demand increases as -butyl groups are replaced with neopentyl groups (P(-Bu)Np < P(Bu)Np < PNp). In square planar palladium(II) complexes, PNp gives the smallest steric parameters, whereas P(Bu)Np has the largest steric demand.

Synthesis, Structural Characterization, and Coordination Chemistry of (Trineopentylphosphine)palladium(aryl)bromide Dimer Complexes ([(NpP)Pd(Ar)Br]).

A series of [(PNp)Pd(Ar)Br] complexes (PNp = trineopentylphosphine, Ar = 4-tolyl, 4--butylphenyl, 2-tolyl, 4-methoxy-2-methylphenyl, 2-isopropylphenyl, and 2,6-dimethylphenyl) were synthesized and structurally characterized by X-ray crystallography and density functional theory optimized structures. The trineopentylphosphine ligand is able to accommodate coordination of other sterically demanding ligands through changes in its conformation. These conformational changes can be seen in changes in percent buried volume of the PNp ligand.

Iridium and Ruthenium Complexes of -Heterocyclic Carbene- and Pyridinol-Derived Chelates as Catalysts for Aqueous Carbon Dioxide Hydrogenation and Formic Acid Dehydrogenation: The Role of the Alkali Metal.

Hydrogenation reactions can be used to store energy in chemical bonds, and if these reactions are reversible, that energy can be released on demand. Some of the most effective transition metal catalysts for CO hydrogenation have featured pyridin-2-ol-based ligands (e.g.

Ruthenium (II) and Iridium (III) Complexes of N-Heterocyclic Carbene and Pyridinol Derived Bidentate Chelates: Synthesis, Characterization, and Reactivity.

We report the synthesis and characterization of new ruthenium(II) and iridium(III) complexes of a new bidentate chelate, NHC-py (OR = OMe, OtBu, OH and R' = Me, Et). Synthesis and characterization studies were done on the following compounds: four ligand precursors (1-4); two silver complexes of these NHC-py ligands (5-7); six ruthenium complexes of the type [η-(p-cymene)Ru(NHC-py)Cl]X with R' = Me, Et and R = Me, tBu, H and X = OTf, PF and POF (8-13); and two iridium complexes, [Cp*Ir(NHC-py)Cl]PF (14) and [Cp*Ir(NHC-py)Cl]POF (15). The complexes are air stable and were isolated in moderate yield.

Ruthenium(ii) complexes of pyridinol and N-heterocyclic carbene derived pincers as robust catalysts for selective carbon dioxide reduction.

A new pincer ligand with N-heterocyclic carbene (NHC) and 4-pyridinol-derived rings supports ruthenium complexes for photocatalytic CO reduction. The methoxy group on the pyridine ring offers unique catalysis advantages not seen with the unsubstituted analog. Our best catalyst offers selective CO formation, ∼250 turnover cycles, and a 40 h lifetime.

Ruthenium Complexes are pH-Activated Metallo Prodrugs (pHAMPs) with Light-Triggered Selective Toxicity Toward Cancer Cells.

Metallo prodrugs that take advantage of the inherent acidity surrounding cancer cells have yet to be developed. We report a new class of pH-activated metallo prodrugs (pHAMPs) that are activated by light- and pH-triggered ligand dissociation. These ruthenium complexes take advantage of a key characteristic of cancer cells and hypoxic solid tumors (acidity) that can be exploited to lessen the side effects of chemotherapy.

Crystal structure of (perchlorato-κ)(1,4,7,10-tetra-aza-cyclo-dodecane-κ)copper(II) perchlorate.

The crystal structure of the title salt, [Cu(ClO)(CHN)]ClO, is reported. The Cu ion exhibits a square-pyramidal geometry and is coordinated by the four N atoms of the neutral 1,4,7,10-tetra-aza-cyclo-dodecane (cyclen) ligand and an O atom from one perchlorate anion, with the second perchlorate ion hydrogen-bonded to one of the amine N atoms of the cyclen ligand. Additional N-H⋯O hydrogen bonds between the amine H atoms and the coordinating and non-coordinating perchlorate groups create a three-dimensional network structure.

Crystal structure of 4'-bromo-2',5'-dimeth-oxy-2,5-dioxo-[1,1'-biphen-yl]-3,4-dicarbo-nitrile [BrHBQ(CN)2] benzene hemisolvate.

In the crystal of the title compound, C16H9BrN2O4·0.5C6H6, the mol-ecules stack in a centrosymmetric unit cell in a 2:1 stoichiometry with co-crystallized benzene solvent mol-ecules and inter-act via various weak inter-actions. This induces a geometry different from that predicted by theory, and is unique among the hemibi-quinones heretofore reported.

Crystal structures of bis- and hexakis[(6,6'-di-hydroxy-bipyridine)copper(II)] nitrate coordination complexes.

Two multinuclear complexes synthesized from Cu(NO3)2 and 6,6'-di-hydroxy-bipyridine (dhbp) exhibit bridging nitrate and hydroxide ligands. The dinuclear complex (6,6'-di-hydroxy-bipyridine-2κ(2) N,N')[μ-6-(6-hy-droxy-pyridin-2-yl)pyridin-2-olato-1:2κ(3) N,N':O (2)](μ-hydroxido-1:2κ(2) O:O')(μ-nitrato-1:2κ(2) O:O')(nitrato-1κO)dicopper(II), [Cu2(C10H7N2O2)(OH)(NO3)2(C10H8N2O2)] or [Cu(6-OH-6'-O-bpy)(NO3)(μ-OH)(μ-NO3)Cu(6,6'-dhbp)], (I), with a 2:1 ratio of nitrate to hydroxide anions and one partially deprotonated dhbp ligand, forms from a water-ethanol mixture at neutral pH. The hexa-nuclear complex bis-(μ3-bi-pyridine-2,2'-diolato-κ(3) O:N,N':O')tetra-kis-(6,6'-di-hydroxy-bipyridine-κ(2) N,N')tetra-kis-(μ-hydroxido-κ(2) O:O')bis-(methanol-κO)tetra-kis-(μ-nitrato-κ(2) O:O')hexa-copper(II), [Cu6(C10H6N2O2)2(CH4O)2(OH)4(NO3)4(C10H8N2O2)4] or [Cu(6,6'-dhbp)(μ-NO3)2(μ-OH)Cu(6,6'-O-bpy)(μ-OH)Cu(6,6'dhbp)(CH3OH)]2, (II), with a 1:1 NO3-OH ratio and two fully protonated and fully deprotonated dhbp ligands, was obtained by methanol recrystallization of material obtained at pH 3.

Studies of the pathways open to copper water oxidation catalysts containing proximal hydroxy groups during basic electrocatalysis.

Water oxidation can lead to a sustainable source of energy, but for water oxidation catalysts to be economical they must use earth abundant metals. We report here 2:1 6,6'-dihydroxybipyridine (6,6'-dhbp)/copper complexes that are capable of electrocatalytic water oxidation in aqueous base (pH = 10-14). Two crystal structures of the complex that contains 6,6'-dhbp and copper(II) in a ratio of 2:1 (complex 1) are presented at different protonation states.

Fischer-Tropsch chemistry at room temperature?

The unique catalytic activity of vanadium nitrogenase suggests a new direction for the direct production of biofuels from CO with either synthetic catalysts or nitrogenase-containing bacteria. The reduction of CO by V nitrogenase to light hydrocarbons shows striking similarities to the established Fischer-Tropsch process; however, the enzyme does not use H(2) directly for this reaction. ADP=adenosine diphosphate, ATP= adenosine triphosphate.

Alternatives to pyridinediimine ligands: syntheses and structures of metal complexes supported by donor-modified alpha-diimine ligands.

This report describes the synthesis and characterization of metal halide complexes (M = Mn, Fe, Co) supported by a new family of pendant donor-modified alpha-diimine ligands. The donor (N, O, P, S) substituent is linked to the alpha-diimine by a short hydrocarbon spacer forming a tridentate, mer-coordinating ligand structure. The tridentate ligands are assembled from monoimine precursors, the latter being synthesized by selective reaction with one carbonyl group of the alpha-dione.