Structure and Luminescence Studies of Salts of the Helical Dication, [Au(μ-bis(diphenylphosphine)ethane)] and Comparison with Salts of [Au(μ-bis(diphenylphosphine)propane)].

Six salts ([Au(μ-dppe)](BF)·CHCl, [Au(μ-dppe)](BF)·1,2-ClCH, [Au(μ-dppe)](PF)·CHCl, [Au(μ-dppe)](PF), [Au(μ-dppe)](SbF), and [Au(μ-dppe)](OTf)·2CHCl), (dppe is bis(diphenylphosphine)ethane) containing the dication, [Au(μ-dppe)], have been prepared and structurally characterized by single-crystal X-ray crystallography. Unlike the three-coordinate dppe-bridged dimers, AuX(μ-dppe) (X = Br, I), which show considerable variation in the distance between the gold(I) ions over the range 3.0995(10) to 3.

Self-Assembled Encapsulation of CuX (X = Br, Cl) in a Gold Phosphine Box-like Cavity with Metallophilic Au-Cu Interactions.

Synthetic routes to the crystallization of two new box-like complexes, [Au(Triphos)(CuBr)](OTf)·(CHCl)·(CHOH)·(HO) () and [Au(Triphos) (CuCl)](PF)·(CHCl) () (triphos = bis(2-diphenylphosphinoethyl)phenylphosphine), have been developed. The two centrosymmetric cationic complexes have been structurally characterized through single-crystal X-ray diffraction and shown to contain a CuX (X = Br or Cl) unit suspended between two Au(I) centers without the involvement of bridging ligands. These colorless crystals display green luminescence (λ = 527 nm) for () and teal luminescence (λ = 464 nm) for ().

Unsymmetrical Coordination of Bipyridine in Three-Coordinate Gold(I) Complexes.

The unsymmetrical coordination of gold(I) by 2,2'-bipyridine (bipy) in some planar, three-coordinate cations has been examined by crystallographic and computational studies. The salts [(PhP)Au(bipy)]XF (X = P, As, Sb) form an isomorphic series in which the differences in Au-N distances range from 0.241(2) to 0.

The Preparation of Luminescent, Mechanochromic Molecular Containers from Non-Emissive Components: The Box Cations, [Au (Triphos) Br] and [Au (Triphos) Br ].

Two new molecular boxes, the mono-bromo box [Au (Triphos) Br](SbF ) ⋅6(CH Cl ), 4 mB, and the dibromo box, [Au (Triphos) Br ⋅H O](SbF ) ⋅4(CH Cl ), 5 dB, have been prepared in crystalline form. Although constructed from non-luminescent components, both are strongly luminescent. Like its chloro counterpart, the mono-bromo box [Au (Triphos) Br](SbF ) ⋅6(CH Cl ), 4 mB, is mechanochromic.

Utilization of a Nonemissive Triphosphine Ligand to Construct a Luminescent Gold(I)-Box That Undergoes Mechanochromic Collapse into a Helical Complex.

Luminescent gold(I) complexes ([Au(Triphos)Cl](PF)·2(CHCH), [Au(Triphos)Cl](AsF)·8(CHCH), and [Au(Triphos)Cl](SbF)·7(CHCH) where Triphos = bis(2-diphenylphosphinoethyl)phenylphosphine) with a boxlike architecture have been prepared and crystallographically characterized. A chloride ion resides at the center of the box with two of the six gold(I) ions nearby. Mechanical grinding of blue luminescent crystals containing the cation, [Au(Triphos)Cl], results in their conversion into amorphous solids with green emission that contain the bridged helicate cation, [μ-Cl{Au(Triphos)}].

Formation of a Stable Complex, RuCl2(S2CPPh3)(PPh3)2, Containing an Unstable Zwitterion from the Reaction of RuCl2(PPh3)3 with Carbon Disulfide.

New insight into the complexity of the reaction of the prominent catalyst RuCl2(PPh3)3 with carbon disulfide has been obtained from a combination of X-ray diffraction and (31)P NMR studies. The red-violet compound originally formulated as a cationic π-CS2 complex, [RuCl(π-CS2)(PPh3)3]Cl, has been identified as a neutral molecule, RuCl2(S2CPPh3)(PPh3)2, which contains the unstable zwitterion S2CPPh3. In the absence of RuCl2(PPh3)3, there is no sign of a reaction between triphenylphosphine and carbon disulfide, although more basic trialkylphosphines form red adducts, S2CPR3.

Emissions savings in the corn-ethanol life cycle from feeding coproducts to livestock.

Environmental regulations on greenhouse gas (GHG) emissions from corn (Zea mays L.)-ethanol production require accurate assessment methods to determine emissions savings from coproducts that are fed to livestock. We investigated current use of coproducts in livestock diets and estimated the magnitude and variability in the GHG emissions credit for coproducts in the corn-ethanol life cycle.

Residual effects of compost and plowing on phosphorus and sediment in runoff.

Manure application can lead to excessive soil test P levels in surface soil, which can contribute to increased P concentration in runoff. However, manure application often results in reduced runoff and sediment loss. Research was conducted to determine the residual effects of previously applied compost, plowing of soil with excessive soil test P, and application of additional compost after plowing on volume of runoff and loss of sediment and P in runoff.

Phosphorus runoff during four years following composted manure application.

Repeated manure application can lead to excessive soil test P (STP) levels and increased P concentration in runoff, but also to improved water infiltration and reduced runoff. Research was conducted to evaluate soil P tests in prediction of P concentration in runoff and to determine the residual effects of composted manure on runoff P loss and leaching of P. The research was conducted from 2001 to 2004 under natural runoff events with plots of 11-m length.

Agroecosystems, nitrogen-use efficiency, and nitrogen management.

The global challenge of meeting increased food demand and protecting environmental quality will be won or lost in cropping systems that produce maize, rice, and wheat. Achieving synchrony between N supply and crop demand without excess or deficiency is the key to optimizing trade-offs amongst yield, profit, and environmental protection in both large-scale systems in developed countries and small-scale systems in developing countries. Setting the research agenda and developing effective policies to meet this challenge requires quantitative understanding of current levels of N-use efficiency and losses in these systems, the biophysical controls on these factors, and the economic returns from adoption of improved management practices.