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Research is done on the change in hardness and chemical potential along a reaction coordinate, which is examined on the basis of the finite difference formula for hardness, and chemical potential. In conclusion, numerical demonstrations of inversion of the NH3 molecule and CH3 radical and isomerization of HCN to HNC are given in support of the theoretical results.

[T1.sub.ρ] RELAXATION STUDIES OF METHYLALUMINOXANE. Amy [Campbell.sup.1], Anthony A. [Mrse.sup.2], Leslie G. [Butler.sup.2], Department of Chemistry, University of North [Alabama.sup.1], Florence, AL 35632, Louisiana State [University.sup.2], Baton Rouge, LA 70803 [...]

The simplest accessible GeON compound H3GeONMe2 was prepared and studied in the gas phase and the solid state. This study was done to assess the influence of the group 14 atom on the molecular structure of the E-O-N units.

A study is conducted, where 2-methyl-2 propyl-ammonium chloride is synthesized and recrystallized from water to determine the kinetics of hydrogen atom abstraction. The resulting radical is oxidized by Cr(sub aq)OO(super 2) to 0-quinone in a fast second step (k= 1.26 * 10(super 4) M(super -1) s(super -1).

The synthesis and O2reaction chemistry of a dicopper(I) complex containing a new unsymmetrical binucleating ligand (UN2-H) are described. The studies show the versatility of copper-dioxygen chemistry involving the bis[21-(2-pyridyl)ethyl]amine (PY2) tridentate chelator or the 2-[2-(methylamino)ethyl]pyridine bidentate group.

Dynamics investigations of two chiral smectogens are measured across the whole mesophasic range by means of the broad band Jeener-Broekaert pulse sequence. Diffusional coefficients relative to spring and internal motions are obtained, which suggests that the analysis of deuterium relaxation data must be performed very cautiously.

The correlation time for side-chain methyl reorientation incrystalline L-alanine is calculated from molecular dynamics simulations and compared with NMR measurements. A torsional parameter in the CHARMM22 force field is reduced on the basis of ab initio calculations for use in the simulations.

Methyl farnesoate (MF) is the unepoxidated form of the most abundant insect juvenile hormone, JH III. MF has been found in more than thirty-five species of Crustacea and is synthesized by the crustacean mandibular organs (MOs). The administration of MF to adult females of several crustacean species results in a stimulation of vitellogenesis. In addition, MF increases in both reproductive males and females. Thus, MF is likely to be a reproductive hormone for both sexes. In addition, the presence of MF in larvae at critical premolt stages interferes with their progression through metamorphosis. Likewise, juvenile males and females retain their juvenile status in the presence of MF at critical times during the premolt rather than progressing to a more differentiated state. MF may function as a morphogen in crustacea. Our understanding of reproductive maturation and morphogenesis of crustacea has been enhanced by a more thorough appreciation of the role of methyl farnesoate.

Carbonic anhydrase (CA) is induced 10-fold in gills of euryhaline crustaceans in low salinity, but regulation of this process is unknown. Recently, increases in methyl farnesoate (MF) in low salinity were correlated to increased Na/K ATPase activity. Eyestalk ablation (ESA) was used to increase MF in crabs to study its effect on CA induction. In Carcinus maenas, ESA resulted in a 25% increase in CA activity in crabs transferred from 33 to 10 ppt but not in crabs transferred from 33 to 28 ppt. Injection of lovastatin, an inhibitor of MF synthesis, did not abolish normal CA induction. Preliminary results in Callinectes sapidus indicate ESA caused a doubling and a 4-fold increase in CA activity in crabs transferred from 35 to 15 or 28 ppt, respectively, vs controls. Slight increases in hemolymph MF levels occurred in ESA treated blue crabs but not in controls. ESA had no effect on CA activity in the stenohaline Cancer irroratus. It appears ESA has a stimulatory effect on CA induction that interacts additively with low salinity. However, this does not appear to be a result of increases in MF. Supported by NSF IN 97-27835.

The synthesis of dihydropyrenyldihydropyrene and spectroscopic evidence for a homo-conjugation effect between the two-pi systems is described. The conclusion states that the behavior of a spiro(homo)-conjugation effect in an electronic spectrum could be shift of the absorption maxima to longer or shorter wavelength.

A study of the reaction of iron oxaphlorin complex with dioxygen in pyridine solution without additional reducing agents present is reported. Experiments carried out show that heme degradation can proceed beyond the ring opening that produces an iron biliverdin complex as well as verdoheme.

Observations that alkaline earth metal orgonometallics are efficient initiators for the anionic living polymerization of styrene and butadiene have led a number of reports of calcium, strontium, and barium complexes, includingbenzylic, acetylenic, and heterometallic 'ate' derivatives, as well as carbene adducts of the decamethylmetallocenes.

It is reported that one can generate analogous photochemistry in two methylated analogues of cis-Rh(phen)(sub 2)Cl2+, cis-diamminedichloro platinum and bis(phenanthroline)Rh, upon their direct excitation into the triplet manifold. Methyl substitution of the aromatic rings increases the triplet photoreactivity of the complexes by 10-fold relative to the unsubstituted analogue.

A new class of easily accessible group 4 complexes that are structurally well-characterized single-site catalyst precursors for isospecific styrene polymerization is presented. The ligand parameters responsible for the activity as well as stereoselectivity of ansa-metallocene mimics are studied.

The first total synthesis of preparation of a key tetetracyclic intermediate containing both the C-11 methyl group and D-ring cyclopropane, and its elaboration into ingenol is reported. The retrosynthetic strategy that is employed for the total synthesis of ingenol is outlined and it anticipated that ingenol should be available from dioxenone photoaddition fragmentation product via the methodology developed in laboratory.

The orientation of polymer functional groups at the polymer interface using SF spectroscopy is demonstrated. It is concluded that the ester methyl groups of PS/poly(methyl methacrylate) (PMMA) are oriented at the interface of the interface within a PS/PMMA blend and this blend is shown to be laterally discontinuous.

The treatment of [RhCI(C8H4)(sub 2)](sub 2) with Bu2PCH2CH2C6H5 leads to the insertion of rhodium into phenyl C - H bond situated in ortho-position to the CH2CH2PBu2 substitutent. A study is conducted that is particularly interested to find out the behavior of a phosphine such as Bu2PCH2CH2C6H(sub 2)-2,4,6-Me3, which has two ring carbon atoms next to the beta-phosphinoethyl moiety blocked by methyl groups.

The quasiclassical trajectory study was reported to examine the mechanism of nonstatistical methyl loss in greater detail. DFT calculations were performed using the gaussian 98(super 10) program.

Reaction of nido-[1,2-(CP*Ru)(sub 2)(mu-H)(sub 2)B3H7] with P(OMe)(sub 3) yielded nido-[1-OMe-2,3-(Cp*Ru)(sub 2){mu-P(OMe)(sub 2)}B3H5] and exhibited methoxy transfer from phosphorous to boron and rearrangement of the cluster core.

Methylene: A Paradigm for Computational Quantum Chemistry THE EXCELLENT RECENT REVIEW BY GODDARD (1) OF theoretical research at California Institute of Technology points to the year 1970 as the origin [...]

Evidence is presented for beta-sheet flexibility and its part in the maturation of protease, obtained from the chemical exchange of the methyl groups.

The chemistry of trifluoromethyl groups adsorbed on metal single-crystal surfaces was examined by the reactions of trifluoromethyl iodide (CF3I) with Ni, Ru, Pt and Ag. Except for Ag, experimental results showed that the C-F bonds could be ruptured. Removal of a single fluorine atom from the CF3 fragment could not be achieved with high selectivity. It was speculated that the choice of metal surfaces might be essential. A unique C-F activation in chemisorbed CF3 moieties using a Cu(111) surface is presented. This is the first example of capable of readily and selectively cleaving a single C-F bond to transform CF3 into CF2 moieties on a well-defined surface.

Research was conducted to examine a new permethylation method for icosahedral closo-boranes employing trimethylaluminum and methyl iodide in the absence of a solvent. The use of two electrophic permethylation methods to (N(n-Bu)4)2 resulted in partial triflation or halogenation. Results indicate that the permethylated dianion may be oxidized in a fashion analogous to that of the monocarborane monoanion (closo-CB11(CH3)12)- to yield the radical ((closo-B12(CH3)12)*)-13.

A stereospecific synthesis of a deuterated methyl alpha-cellobioside is reported as part of the detailed analysis of carbohydrate conformation and dynamics. The synthesis proceeded from the removal of the 4,6-benzylidene group with 90% trifluoroacetic acid. The stereospecific intramolecular reduction, followed by a glycosylation reaction, yielded a site-specifically deuterated methyl alpha-cellobioside. The latter is currently used to further study carbohydrate flexibility and dynamics.

The mechanism of selective coupling of methylene units in a Rh/Os complex has been investigated. To this end, model studies on a diphosphine-bridged RhOs complex, in which the facile coupling of methylene units takes place, were conducted. Selective coupling results in the formation of either C(sub 3) or C(sub 4) fragments bound to the metals, suggesting the potential application of metals with different properties in Fischer-Tropsch chemistry.

A study was conducted on the close intramolecular associations between the sterically hindered CH(SiMe3)2 alkyl group and a lanthanide. The experiment reports the first neutron diffraction studies of certain lanthanide complexes on (C5Me5)Y(OC6H(sub 3)(supra tBu2))CH(SiMe3)2 at 20 K and (C5Me5)La{CH(SiMe3)2}2 at 15 K. Results of the study clearly show that the betaSiC agostic interaction predominates.

Tests were conducted to evaluate the feasibility of using the regioselective aldolization of commercial 2-methylcyclopentanone to synthesize the enone 2-chlorophenyl methylidene-5,5-dimethylcyclopentanone. Results revealed several advantages of the procedure. First, the complex preparation of 2,2-dimethylcyclopentanone was avoided. Second, any mixture of enoxysilanes can be used to begin the procedure.

Research was conducted to examine scalar and dipolar coupling studies of organocuprates. The objectives were to investigate the idea that the ground-state structures for some cuprates are actually higher order and to define the role of the lithium ion in organocuprates. Results indicate that the coupling patterns available in the 1H and proton coupled 13C NMR spectra of fully 13 C-labeled organocuprates permit the differentiation between the ground-state structures of lower- and higher-order organocuprates.

The steric course of the methylation by G-protein methyltransferase, methyl-R- and methyl-S-(methyl-2H1,3H)AdoMet prepared previously, were used as methyl donors and S-farnesyl-3-thiopropionate (FTP) as a model substrate. Stereospecifically tritiated AdoMet samples were incubated with FTP and G-protein methyltransferase from rod outer segment (ROS) membranes. Results reveal that the G-proteins of ROS were reversibly methylated and demethylated. The stereochemistry established by the study is in agreement with the majority of AdoMet-dependent methyltransferases.

A study was conducted on C5 methylene intermediate trapping in thymidylate synthase which catalyzes the conversion of 2'-deoxyuridine-5'-phosphate to thymidine -5'-phosphate. The covalent adduct formed by the reaction was observed to break down and produce exocyclic methylene intermediate and promote hydride transfer from 5,6,7,8-tetrahydrofolate. Trapping experiments employing Lactobacillus casei thymdiylate synthase Trp82Tyr mutant demonstrate the development of the C5 methylene intermediate .

The hydrophobic spine of the thymine methyl groups in the Hoogsteen-Watson groove of the dT*dA.dT base triplex is the probable binding site of the second netropsin and the grooves are better defined if the salt concentration is high. In the base triplex where the two thymine methyl groups are aligned in the same groove, the hydrophobic interactions are effective.

The stereospecific assignment of leucine methyl groups is undertaken using a heteronuclear NMR procedure. The procedure may be used for both polypeptides with carbon in natural abundance and randomly labeled polypeptides possessing 13C at least in the delta positions. Moreover, the stereochemical assignment of the H(sub beta) protons and the resolution in either the carbon or proton domain of the signals of the two methyl groups are necessary. There are no constraints on the method and is applied with leucine in cyclolinopeptide A.

1H NMR spectroscopy is utilized in the investigation of the chirotopicity of the methyl group in (alpha-deuterio-o-chlorotoluene)chromium tricarbonyl. The hydrogens of a chirotopic methylene group are located in diastereotopic environments and chirotopicity is usually exhibited as an AB pattern in the 1H NMR spectrum of the molecule. The tricarbonyl compound is prepared from the reduction of alpha-bromo-o-chlorotoluene with lithium aluminum deuteride in tetrahydrofuran, followed by treatment with chromium hexacarbonyl in refluxing diglyme.

Research is presented describing an investigation into the vibrational overtones of the methylpyridines, recorded at room temperature, using intracavity laser photoacoustic spectroscopy and conventional absorption spectroscopy.

The interaction of vapor-deposited aluminum atoms with self-assembled monolayers (SAMs) of HS(CH2)15CH3 and HS(CH2)15CO2CH3 at Au(111) surfaces was investigated by X-ray photoelectron spectroscopy, infrared spectroscopy, time-of-flight secondary ion mass spectrometry and spectroscopic ellipsometry. Findings demonstrate the unusual degree of regulation that organic substrates can apply during the course of metal film formation.

Research was conducted to examine the orientations of three methyl bonds of the retinylidene chromophore of bacteriorhodopsin in the M photointermediate using deuterium solid-state NMR. The manner with which the angles between the respective C-C bond and the membrane normal changed in the transition from the ground to the M state was also investigated. Results showed that the angles between the bonds and the membrane normal were greater in M than in the ground state, suggesting an out-of-plane tilt of the retinal or a substantial torsional strain.

Research was conducted to investigate the impact of the D-methyl substituent (vs hydrogen) on the free energy of the acylation and deacylation transition states and of the acyl-enzyme intermediate for turnover of a peptide substrate by a DD-peptidase and by a structurally similar beta-lactamase. Free energy-reaction coordinate diagrams for hydrolysis of the peptides by the DD-peptidase and beta-lactamase in evaluating the comparative effect of the D-methyl substituent on the enzymes at all stages of catalysis were constructed. Results demonstrate the important role of the methyl group in beta-lactamase evolution.

Variable-time neutralization-reionization mass spectrometry together with fast-beam laser photoexcitation as well as G2(MP2) ab initio/RRKM computations were used in studying methylsulfonyl and methoxysulfinyl radicals. Femtosecond collisional electron transfer in the gas phase was used in producing the radicals. Both radicals have been observed to be stable in the gas phase. The methylsulfonyl radical decomposes to CH3* and SO2 due to the large Franck-Condon energy associated with the neutralization. The methoxysulfinyl radical exists as a combination of syn and anti isomers.

The Schiff base model was used to examine the potential impact of methyl substitutions on carbon atoms in the context of proton affinity (PA), charge distribution and structure. All the samples observed did not exhibit marked structural changes upon the application of large basis sets. It was also shown that methyl substitutions tend to create a direct effect on PA level by determining the overall shape of the chromophore.

Research was conducted to determine the crystal structure of rat liver S-adenosyl-L-homocysteine hydrolase (AdoHcyase EC3.3.1.1) at 2.8 angstroms resolution. The polypeptide folding pattern of the catalytic domain indicates that AdoHcy molecules can travel freely to and from AdoHcyase and methyltransferases to properly regulate methyltransferase activities. Therefore, the crystal structure can provide insight into the molecular architecture of the regulatory enzyme.

The concentrations of the methyl radical and stable complexes in an ac methane/hydrogen/oxygen (CH(sub 4)-H(sub 2)-O(sub 2)) plasma are calculated using infrared diode laser spectroscopy. All of the stable C-2 hydrocarbons and oxygen-bearing species including formaldehyde, methanol, formic acid, carbon dioxide and carbon monoxide are among the stable products detected. Good agreement between the model and observed concentrations of the detected species is also found.

The bimolecular interactions of metal-bound methyl and perfluoromethyl in conjunction with coadsorbed methylene were examined utilizing a temperature-programmed reaction spectroscopy. The methylene insertion reaction was considered a significant method for transforming coal to gasoline. It was concluded that methyl undergoes a self-coupling reaction to produce ethane, methylene is dimerized to produce ethylene and that trifluoromethyl desorbs as a radical.

A theoretical and spectroscopic study of gaseous monohydrogenated toluene and 4-methylpyridine was conducted. The objective of the study is to simulate vibrational CH-stretching spectra reflecting the coupling between the methyl CH vibrators and the internal rotation. Results indicate that the molecular environment of the methyl group is the origin of some spectral differences, essentially associated with differences in electric anharmonicity.