Multimetallic arrays: bi-, tri-, tetra-, and hexametallic complexes based on gold(I) and gold(III) and the surface functionalization of gold nanoparticles with transition metals.

Reaction of [AuCl(PPh(3))] with the zwitterion S(2)CNC(4)H(8)NH(2) yields [(Ph(3)P)Au(S(2)CNC(4)H(8)NH(2))]BF(4). Treatment of this species with NEt(3) and CS(2) followed by [AuCl(PPh(3))] leads to [{(Ph(3)P)Au}(2)(S(2)CNC(4)H(8)NCS(2))], which can also be obtained directly from [AuCl(PPh(3))] and KS(2)CNC(4)H(8)NCS(2)K. A heterobimetallic variant, [(dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2))Au(PPh(3))](+), can be prepared by the sequential reaction of [(dppm)(2)Ru(S(2)CNC(4)H(8)NH(2))](2+) with NEt(3) and CS(2) followed by [AuCl(PPh(3))]. Reaction of the same ruthenium precursor with [(dppm)(AuCl)(2)] under similar conditions yields the trimetallic complex [(dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2))Au(2)(dppm)](2+). Attempts to prepare the compound [(dppm)Au(2)(S(2)CNC(4)H(8)NH(2))](2+) from [(dppm)(AuCl)(2)] led to isolation of the known complex [{(dppm)Au(2)}(2)(S(2)CNC(4)H(8)NCS(2))](2+) via a symmetrization pathway. [{(dppf)Au(2)}(2)(S(2)CNC(4)H(8)NCS(2))](2+) was successfully prepared from [(dppf)(AuCl)(2)] and crystallographically characterized. In addition, a gold(III) trimetallic compound, [{(dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2))}(2)Au](3+), and a tetrametallic gold(I) species, [{(dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2))Au}(2)](2+), were also synthesized. This methodology was further exploited to attach the zwitterionic (dppm)(2)Ru(S(2)CNC(4)H(8)NCS(2)) unit to the surface of gold nanoparticles, which were generated in situ and found to be 3.4 (+/-0.3) and 14.4 (+/-2.5) nm in diameter depending on the method employed. Nanoparticles with a mixed surface topography were also explored.

Bio-inspired CO2 conversion by iron sulfide catalysts under sustainable conditions.

The mineral greigite presents similar surface structures to the active sites found in many modern-day enzymes. We show that particles of greigite can reduce CO2 under ambient conditions into chemicals such as methanol, formic, acetic and pyruvic acid. Our results also lend support to the Origin of Life theory on alkaline hydrothermal vents.

Synthesis, structure and reactivity of tetranuclear square-type complexes of rhenium and manganese bearing pyrimidine-2-thiolate (pymS) ligands: versatile and efficient precursors for mono- and polynuclear compounds containing M(CO)(3) (M = Re, Mn) fragments.

Reactions of M(2)(CO)(10) (M = Re, Mn) with pyrimidine-2-thiol (pymSH) in the presence of Me(3)NO afford the tetranuclear square-type complexes [M(4)(CO)(12)(micro-kappa(3)-pymS)(4)] (, M = Re; , M = Mn). Both consist of four M(CO)(3) (M = Re, Mn) units, pairs of which are joined by tridentate pyrimidine-2-thiolate ligands. Treatment of with a variety of donor ligands results in cleavage of the square to afford mononuclear species with either a mono- or bidentate pyrimidine-2-thiolate ligand. Triphenylphosphine reacts with to give [Mn(CO)(3)(PPh(3))(kappa(2)-pymS)] () in which the pyrimidine-2-thiolate coordinates in a bidentate fashion. With diamines [M(CO)(3)(kappa(2)-L)(kappa(1)-pymS)] () (M = Re, Mn; L = 2,2'- bipy, 1,10-phen, en) result in which the pyrimidine-2-thiolate binds in a monodentate fashion through sulfur. With diphosphines, complexes with different stoichiometries and pyrimidine-2-thiolate binding modes are obtained depending on the nature of the metal and diphosphine. With dppm and dppe, gives [Re(CO)(2)(kappa(1)-pymS)(kappa(2)-dppm)] () and [Re(CO)(2)(kappa(2)-pymS)(kappa(1)-dppe)(2)] (), respectively, whereas affords [Mn(CO)(2)(kappa(2)-pymS)(kappa(1)-dppm)(2)] () and [Mn(CO)(2)(kappa(2)-pyS)(kappa(2)-dppe)] () under similar conditions. Reactions of with [Os(3)(CO)(10)(NCMe)(2)] affords mixed-metal butterfly clusters [MOs(3)(CO)(13)(micro(3)-kappa(2)-pymS)] () in which the group 7 metal occupies a wing-tip position and the pyrimidine-2-thiolate ligand caps a triangular Os(2)M face. With Ru(3)(CO)(12), carbon-sulfur bond cleavage occurs to give the tetranuclear clusters [MRu(3)(CO)(14)(micro(4)-S)(micro-kappa(1):eta(1)-pym)] () bearing both the extruded sulfur and the heterocyclic ring. The molecular structures of , and have been established by X-ray diffraction allowing the binding mode of the pyrimidine-2-thiolate ligands to be probed.

Behaviour of laying hens in a deep litter house.

1. Flocks of medium hybrid laying hens were housed in a modified deep litter system; the house was divided into 2, 3 and 4 pens in three successive years. Flock size was 300 or 370 and stocking density varied from 3.4 to 10.7 birds/m2. Higher densities used were above those recommended by the Ministry of Agriculture, Fisheries and Food (MAFF). 2. A random sample of 100 birds was identified with individual tags in each of the 9 flocks; regular observations using a scanning technique were made in each laying cycle to determine bird location and behaviour. 3. In all flocks the use of area by some individuals was uneven, that is, they were sighted in certain areas significantly more often than would have been expected by chance. The proportion of such individuals varied between flocks from 35 to 65%. Overall, birds spent more time on the slatted area than would have been expected from the area that it occupied. 4. A wide variety of different behaviour patterns was observed both on litter and on slats, but with foraging occurring more on litter and feeding more on slats. 5. Movement appeared to be constrained by crowding, because time spent in locomotion decreased in approximately linear fashion with increased stocking density. This provides support for MAFF recommendations of limits on stocking density in deep litter houses.