Six possible complexes of glyphosate (O-PO(OH)-CH2NH2+CH2CO2H) with an Fe-hydroxide dimer were modeled with hybrid molecular orbital/density functional theory calculations to establish the nature of the bonds of glyphosate on goethite (alpha-FeOOH). Monodentate and bidentate coordination of the phosphonate moiety were considered, using three forms of the glyphosate molecule appropriate for different pH ranges: glyphosate with both phosphonate and amino moieties protonated, glyphosate with unprotonated phosphonates, and glyphosate with both unprotonated phosphonates and no hydrogen ion on the amino group. The calculated infrared vibrational modes were compared to experimental values, finding particularly good agreements with the monodentate complexes in all the pH ranges.

Solid state polymerization has the potential to afford topochemical control over reaction pathways. Highpressure solid state polymerization at low temperature may permit a single lowest energy reaction pathway to be favored and also allow reactants to approach more closely before reaction begins, both factors that may favor topochemical reaction. Acetylene begins to polymerize in the solid state at a pressure of 12.5 GPa at 77 K. Further reaction occurs upon release of pressure to 2.5 GPa, suggesting the presence of unsatisfied reactive sites at high pressure. A topochemical polymerization did not result, but Raman spectroscopy indicates the formation of some polymer, which exhibits a spectrum characteristic of cis-polyacetylene. This polymer isomerized to the trans form upon warming to 298 K.

Salicylic and phthalic acids have been used to study the complexation of aromatic carboxylic acids with Al(III) in solution and on mineral surfaces. A method for studying aqueous and surface carboxylic acids/ metal complexes with UV Raman has been developed. The acids and Al(III) solutions were mixed in a 1:1 ratio at concentrations of 0.01 M. The mixtures were adjusted to pH 2.5 and 4 to be above and below the pK a1 values of the carboxylic acids. The pH values of the acid solutions were based on the pK a values for the different acids to examine the neutral and charged species. The carboxylic acids were also adsorbed onto Al 2 O 3 . Comparisons between solution and adsorbed complexes were examined. Various possible types of complexes for the metal/acid complexes were modeled with ab initio molecular orbital/density functional theory calculations. The assignments of Al(III)-acid complexes were based on the best fits between experimental and model vibrational frequencies. Results are compared to previous speciation models based on potentiometric data.

A continuing challenge in understanding the linkage of unsaturated molecules to produce novel networks has been the analysis of the reaction products. Here we report a UV Raman spectroscopic analysis of the amorphous C:H (a-C:H) network formed by compression of benzene. The network contains both sp 2 -and sp 3 -bonded carbon, indicating that the aromaticity of some of the benzene rings must have been destroyed during the formation of the network. The Raman spectrum of the network resembles that of hydrogen-rich polymeric a-C:H. Analysis by means of UV Raman spectroscopy of a wide range of novel networks produced by compression of unsaturated molecules should be possible.