Furfural to 1,4-Butanediol/Tetrahydrofuran - A Detailed Catalyst and Process Design.

The feasibility to convert furan, a direct derivative of furfural, to a mixture of 1,4-butanediol (BDO) and tetrahydrofuran (THF) is demonstrated with industrially acceptable performances using mm-sized pellets of a carbon-supported RePd catalyst for 2000 h of operation. The reaction schemes were unraveled by spiking potential reaction intermediates and a full kinetic model was developed. Finally, we developed a comprehensive process flow scheme that integrates the conversion of furfural to furan, the recovery and purification of furan, its reductive hydration to BDO/THF as well as the recovery and purification of BDO and THF.

Redox chemistry and electronic properties of 2,3,5,6-tetrakis(2-pyridyl)pyrazine-bridged diruthenium complexes controlled by N,C,N'-biscyclometalated ligands.

To investigate the consequences of cyclometalation for electronic communication in dinuclear ruthenium complexes, a series of 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz) bridged diruthenium complexes was prepared and studied. These complexes have a central tppz ligand bridging via nitrogen-to-ruthenium coordination bonds, while each ruthenium atom also binds either a monoanionic, N,C,N'-terdentate 2,6-bis(2'-pyridyl)phenyl (R-N(wedge)C(wedge)N) ligand or a 2,2':6',2''-terpyridine (tpy) ligand. The N,C,N'-, that is, biscyclometalation, instead of the latter N,N',N''-bonding motif significantly changes the electronic properties of the resulting complexes.

Selective para-halogenation and dimerization of N,C,N'-arylruthenium(II) and -(III) 2,2':6',2''-terpyridine cations.

The N,C,N'-bonded arylruthenium 2,2':6',2''-terpyridine (tpy) complex salts [Ru(NCN)(tpy)](Cl) ([1a](Cl), NCN = 2,6-bis[(dimethylamino)methyl]phenyl) and [Ru(N--C--N)(tpy)](PF(6)), ([2a](PF(6)), N--C--N = 2,6-bis(2-pyridyl)phenyl) can be halogenated under very mild conditions by oxidation with copper(II) halogen salts. Halogenation occurs exclusively para to the site of metalation and yields the cations [Ru(4-R-NCN)(tpy)](+) (R = Cl, [1b](+) and R = Br [1c](+)) and [Ru(4-R-N--C--N)(tpy)](+) (R = Cl, [2b](+) and R = Br [2c](+)). In the presence of an excess of oxidant relative to [1a](+), the halogenation reaction follows first order kinetics in the oxidized ruthenium complex.

Consequences of N,C,N'- and C,N,N'-coordination modes on electronic and photophysical properties of cyclometalated aryl ruthenium(II) complexes.

The effects of isoelectronic replacement of a neutral nitrogen donor atom by an anionic carbon atom in terpyridine ruthenium(II) complexes on the electronic and photophysical properties of the resulting N,C,N'- and C,N,N'-cyclometalated aryl ruthenium(II) complexes were investigated. To this end, a series of complexes was prepared either with ligands containing exclusively nitrogen donor atoms, that is, [Ru(R(1)-tpy)(R(2)-tpy)](2+) (R(1), R(2) = H, CO(2)Et), or bearing either one N,C,N'- or C,N,N'-cyclometalated ligand and one tpy ligand, that is, [Ru(R(1)-N(/\)C(/\)N)(R(2)-tpy)](+) and [Ru(R(1)-C(/\)N(/\)N)(R(2)-tpy)](+), respectively. Single-crystal X-ray structure determinations showed that cyclometalation does not significantly alter the overall geometry of the complexes but does change the bond lengths around the ruthenium(II) center, especially the nitrogen-to-ruthenium bond length trans to the carbanion.

Cyclometalated ruthenium complexes for sensitizing nanocrystalline TiO2 solar cells.

Cyclometalated ruthenium complexes of [Ru(C--arrow--N) (N--N--N)] configuration are a promising new class of molecular sensitizers for dye-sensitized solar cells, as a result of their broad and red-shifted visible absorption in comparison to the analogous [Ru(N--N--N)2] type coordinative complexes.