Diruthenium Phenylacetylide Complexes Bearing para-/meta-Amino Phenyl Substituents

Ultrasound-assisted synthesis of water-soluble monosubstituted diruthenium compounds

The elusive monosubstituted diruthenium complexes [Ru₂Cl(DAniF)(O₂CMe)₃] (1), [Ru₂Cl(DPhF)(O₂CMe)₃] (2), [Ru₂Cl(D-p-CNPhF)(O₂CMe)₃] (3), [Ru₂Cl(D-o-TolF)(O₂CMe)₃] (4), [Ru₂Cl(D-m-TolF)(O₂CMe)₃] (5), [Ru₂Cl(D-p-TolF)(O₂CMe)₃] (6) and [Ru₂Cl(p-TolA)(O₂CMe)₃] (7) have been synthesized using for the first time ultrasound-assisted synthesis to carry out a substitution reaction in metal-metal bonded dinuclear compounds (DAniF^- = N,N'-bis(4-anisyl)formamidinate; DPhF^- = N,N'-diphenylformamidinate; D-p-CNPhF^- = N,N'-bis(4-cyanophenyl)formamidinate; D-o/m/p-TolF^- = N,N'-bis(2/3/4-tolyl)formamidinate; p-TolA^- = N-4-tolylamidate). This is a simpler and greener method than the tedious procedures described in the literature, and it has permitted to obtain water-soluble complexes with good yields in a short period of time. A synthetic study has been implemented to find the best experimental conditions to prepare compounds 1-7. Two different types of ligands, formamidinate and amidate, have been used to check the generality of the method for the preparation of monosubstituted complexes. Five new compounds (2-6) have been obtained using a formamidinate ligand, the synthesis of the previously described compound 1 has been improved, and an unprecedented monoamidate complex has been achieved (7). The crystal structures of compounds 3 and 7 have been solved by single crystal X-ray diffraction. These compounds show the typical paddlewheel structure with three acetate ligands and one formamidinate (3) or amidate (7) bridging ligand at the equatorial positions. The axial positions are occupied by the chloride ligand giving rise to one-dimensional polymer structures that were previously unknown for monosubstituted compounds.

Synthesis, Structural and Physicochemical Properties of Water-Soluble Mixed-Ligand Diruthenium Complexes Containing Anilinopyridinate Bridging Ligands

A series of water-soluble Ru₂⁵⁺ complexes of the type Ru₂(O₂CCH₃)₃(L)Cl where L = 2,3,4,5,6-F₅ap, 2,4,6-F₃ap, 2-Fap, ap, 2-Meap, 2,6-Me₂ap, or 2,4,6-Me₃ap, where ap is the anilinopyridinate anion, have been characterized as to their structural and physicochemical properties in H₂O and DMSO. Five of the newly synthesized complexes were structurally characterized, and the Ru-Cl bond lengths range from 2.477 to 2.544 Å while the Ru-Ru bond lengths range from 2.2838 to 2.2935 Å. The UV-vis spectra of each compound are characterized by three absorption bands in both H₂O and DMSO, the intensity and position of which vary with both the type of bridging ligand and the solvent. The seven examined Ru₂⁵⁺ complexes exist as 1:1 electrolytes in water, and each undergoes a reversible one-electron reduction assigned to Ru₂⁵⁺/Ru₂⁴⁺ in both investigated solvents. A second irreversible reduction attributed to Ru₂⁴⁺/Ru₂³⁺ is also observed for each compound at more negative potentials in DMSO. A linear free energy relationship exists between the sum of the Hammett substituent constants (Σσ) on the ap-type bridging ligand and the wavenumber of an absorption band for the Ru₂⁵⁺ complexes. A linear relationship is also seen between Σσ and measured E_1/2 values for the Ru₂⁵⁺/Ru₂⁴⁺ process in water containing 0.1 M KCl, but little to no effect is seen between the specific bridging ligand and the structural features of the investigated compounds.

Crystal structure of N-(2-benzoyl-5-ethynylphen-yl)quinoline-2-carboxamide

In the title compound, C25H16N2O2, the quinoline ring system is essentially planar, with a maximum deviation of 0.030 (1) Å, and forms a dihedral angle of 20.9 (1)° with benzoyl benzene ring. The unsubstituted phenyl ring forms dihedral angles of 52.7 (1)° with the quinoline ring system and 54.1 (1)° with the ethynyl-substituted benzene ring. The mol-ecule contains an intra-molecular bifurcated N-H⋯(O,N) hydrogen bond, forming S(5) and S(6) rings, which may influence the conformation of the mol-ecule. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network. In addition, the three-dimensional structure contains π-π stacking inter-actions, with centroid-centroid distances of 3.695 (1) and 3.751 (1) Å.

Anilinopyridinate-supported Ru2x+ (x = 5 or 6) paddlewheel complexes with labile axial ligands

Five new metal–metal bonded Ru₂ amidinate compounds with labile axial ligands are presented and discussed.

Non-volatile memory devices with redox-active diruthenium molecular compound

Reduction-oxidation (redox) active molecules hold potential for memory devices due to their many unique properties. We report the use of a novel diruthenium-based redox molecule incorporated into a non-volatile Flash-based memory device architecture. The memory capacitor device structure consists of a Pd/Al2O3/molecule/SiO2/Si structure. The bulky ruthenium redox molecule is attached to the surface by using a 'click' reaction and the monolayer structure is characterized by x-ray photoelectron spectroscopy to verify the Ru attachment and molecular density. The 'click' reaction is particularly advantageous for memory applications because of (1) ease of chemical design and synthesis, and (2) provides an additional spatial barrier between the oxide/silicon to the diruthenium molecule. Ultraviolet photoelectron spectroscopy data identified the energy of the electronic levels of the surface before and after surface modification. The molecular memory devices display an unsaturated charge storage window attributed to the intrinsic properties of the redox-active molecule. Our findings demonstrate the strengths and challenges with integrating molecular layers within solid-state devices, which will influence the future design of molecular memory devices.

Attachment of a diruthenium compound to Au and SiO2/Si surfaces by "click" chemistry

Fabrication of electrodes with functionalized properties is of interest in many electronic applications with the surface impacting the electrical and electronic properties of devices. We report the formation of molecular monolayers containing a redox-active diruthenium(II,III) compound to gold and silicon surfaces via "click" chemistry. The use of Cu-catalyzed azide-alkyne cycloaddition enables modular design of molecular surfaces and interfaces and allows for a variety of substrates to be functionalized. Attachment of the diruthenium compound is monitored by using infrared and photoelectron spectroscopies. The highest occupied molecular (or system) orbital of the "clicked-on" diruthenium is clearly seen in the photoemission measurements and is mainly attributed to the presence of the Ru atoms. The "click" attachment is robust and provides a route to investigate the evolution of the electronic structure and properties of novel molecules attached to a variety of electrodes. The ability to attach this redox-active Ru molecule onto SiO2 and Au surfaces is important for the development of functional molecular devices such as charge-based memory devices.

Diruthenium(III,III) ethynyl-phenyleneimine molecular wires: preparation via on-complex Schiff base condensation

The diruthenium compound trans-Ru(2)(DMBA)(4)(C≡C-C(6)H(4)-4-CHO)(2) (1; DMBA is N,N'-dimethylbenzamidinate) was prepared from the reaction between Ru(2)(DMBA)(4)(NO(3))(2) and HC≡C-C(6)H(4)-4-CHO under the weak base conditions. The aldehyde groups of 1 undergo a condensation reaction with NH(2)C(6)H(4)-4-Y (Y = H and NH(2)) to afford new compounds trans-Ru(2)(DMBA)(4)(C≡C-C(6)H(4)-4-CH═N-C(6)H(4)-4'-Y)(2) (Y = H (2) and NH(2) (3)). A related compound, Ru(2)(DMBA)(4)(C≡C-C(6)H(4)-4-N═C(Me)Fc)(2) (4), was also prepared from the reaction between Ru(2)(DMBA)(4)(NO(3))(2) and HC≡C-C(6)H(4)-N═C(Me)Fc. X-ray structural studies of compounds 1 and 2 revealed significant deviation from an idealized D(4h) geometry in the coordination sphere of the Ru(2) core. Voltammetric measurements revealed four one electron redox processes for compounds 1-3: the Ru(2) centered oxidation and reduction, and a pair of reductions of the imine or aldehyde groups. Compound 4 displays an additional oxidation attributed to the Fc groups. DFT calculations were performed on model compounds to gain a more thorough understanding of the interaction of the organic functional groups across the diruthenium bridge.