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Space radiation has recently been considered a risk factor for astronauts&rsquo, cardiac health. As an example, for the case of how to query and identify datasets within NASA&rsquo, s GeneLab database and demonstrate the database utility, we used an unbiased systems biology method for identifying key genes/drivers for the contribution of space radiation on the cardiovascular system. This knowledge can contribute to designing appropriate experiments targeting these specific pathways. Microarray data from cardiomyocytes of male C57BL/6 mice followed-up for 28 days after exposure to 900 mGy of 1 GeV proton or 150 mGy of 1 GeV/n 56Fe were compared to human endothelial cells (HUVECs) cultured for 7 days on the International Space Station (ISS). We observed common molecular pathways between simulated space radiation and HUVECs flown on the ISS. The analysis suggests FYN is the central driver/hub for the cardiovascular response to space radiation: the known oxidative stress induced immediately following radiation would only be transient and would upregulate FYN, which in turn would reduce reactive oxygen species (ROS) levels, protecting the cardiovascular system. The transcriptomic signature of exposure to protons was also much closer to the spaceflight signature than 56Fe&rsquo, s signature. To our knowledge, this is the first time GeneLab datasets were utilized to provide potential biological indications that the majority of ions on the ISS are protons, clearly illustrating the power of omics analysis. More generally, this work also demonstrates how to combine animal radiation studies done on the ground and spaceflight studies to evaluate human risk in space.

Phosphate–ZrO2–Si2O catalysts were synthesized by sol-gel method using tributyl phosphite, zirconium propoxide, and tetraethyl orthosilicate as precursors. They were characterized by N2 adsorption, 31P CP MAS NMR, and DRIFTS. At lower P content, monomeric phosphates were formed on the surface of the catalysts, which were mainly responsible for the isopropanol dehydration activity. At higher P content, polyphosphates were formed, and thus, the dehydration activity decreased. An optimum P content for dehydration activity was found to be at 10 mol%.Key words: sol-gel synthesis, ternary oxides, phosphate, acid catalyst, alcohol dehydration, 31P CP MAS NMR, N2 adsorption, DRIFTS.

A detailed study of the solution chemistry and mass spectrometry of six carboxylato-organogermanium compounds in aqueous solution has been carried out using electrospray ionization and MSn techniques. The different types of hydrolysis products and their probable structures, which include the oligomers and their fragment ions plus water adduct ions formed by ion-molecule reactions, are presented, e.g., HO-cyclic-(-Ge(O−)CH2CH2COO) A, HO-cyclic-(-Ge(O-cyclic-(Ge(O−)CH2CH2COO)CH2CH2COO) B, −OGeO-cyclic-(-Ge(OH)CH2CH2COO) C, and −CH=CHGeO-cyclic-(-Ge(OH)CH2CH2COO) D, etc. The proposed cyclic structures are confirmed by theoretical calculations. Copyright © 2001 John Wiley & Sons, Ltd.

ZnCl2–aluminosilicate catalysts were prepared via a sol–gel route involving fluoride‐catalyzed hydrolysis of aluminum and silicon alkoxides in the presence of NaF, KF, NH4F and ZnF2. The catalysts were characterized by employing 29Si, 27Al and 19F solid‐state MAS NMR. The dependence of the activities of the catalysts on the nature and amount of fluoride present in the catalysts were investigated using Friedel–Crafts alkylation reaction of benzene with benzyl chloride.

Novel mesoporous silicas have been prepared via a sol-gel route involving fluoride-catalyzed hydrolysis of tetraethylorthosilicate (TEOS). Incorporation of zinc chloride by sol-gel synthesis gives a range of mesoporous materials with significantly higher catalytic activity than the commercially available catalyst, Clayzic, in a model Friedel-Crafts alkylation reaction. The dependence of catalytic activity and physical structure on the amounts of solvent, water, zinc chloride, and potassium fluoride used in the preparation are explored, and the materials have been further characterized by nitrogen adsorption to determine surface areas, total pore volumes, and pore-size distributions and by 29Si and 19F MAS NMR spectroscopy. The most active catalysts generally have the highest total pore volumes, with pore-size distributions larger than 8 nm.Key words: sol-gel, Friedel-Crafts, Clayzic, silica.

Complete EI and positive-ion FAB (matrix liquids: 2-nitrophenyl octyl ether (NPOE) and 3-nitrobenzyl alcohol (NBA)) mass spectra are reported for Ar 4 Sn(Ar = p -Tol, m -Tol, 3,5-Xyl, σ -Tol, p -FC 6 H 4 , m -FC 6 H 4 , 3,5-F 2 C 6 H 3 , p -ClC 6 H 4 , 3,5-Cl 2 C 6 H 3 , p -CF 3 C 6 H 4 , and m -CF 3 C 6 H 4 ) and Ar 3 SnX (Ar  Mes, X  Cl, Br, I; Ar = o -Tol. X = 1). Comparison with phenyltin data shows methyl substituents produce little change in disintegration patterns except when in the ortho -position, in which case loss of ArH is promoted. Halogen substituents produce both substituent type and position effects in disintegration patterns. Differences are seen between E1 and positive-ion FAB mass-spectra results which would indicate that for the latter, matrix mediated processes are more significant than gas-phase disintegration pathways. Negative-ion FAB mass spectra were observed for only a few of the compounds studied in this work.

Substituted benzoic and cinnamic acids were studied by FAB mass spectrometry using matrix-based Al(III) ions. Complex ions derived from these acids, such as ( M + 117 )+ ( 117 = (Al + glycerol − 2H)+ ), ( M + 159 )+ ( 159 = [2Al + 2glycerol − 5H − 74(epoxypropanol)]+), and ( M + 233)+ ( 233 = (2Al + 2glycerol − 5H)+), when subjected to collisionally activated dissociation (CAD), gave an ion corresponding to ( M − OH)+. Formation of this ion was explained by the transfer of the carboxylic -OH group to the ( Al + glycerol − 2H)+, ( 2Al + 2glycerol − 5H − 74 )+, and ( 2Al + 2glycerol − 5H )+ portion of the complexes. This transfer is more pronounced in the case of meta- and para-substituted acids. The CAD of the ( M + 117 )+ ions yielded ( M + Al(III) )+ ions resulting from the insertion of Al(III) into the carboxylic acid, which was followed by the elimination of CO to produce ( M + Al(III) − CO)+ ions. Interpretation of spectral data was clarified by study of the formation and fragmentation of ions produced from deuterated benzoic and cinnamic acids. Keywords: substituted benzoic and trans-cinnamic acids, Al(III)–glycerol, FAB mass spectrometry, ionic metal complexes, collisionally induced dissociation, Al(III) insertion, carbonyl cations.

The complexation reactions of aluminum ions with polydentate ligands such as 12-crown-4,15-crown-5,18-crown-6, 1,10-dithia-18-crown-6, dicyclohexyl-18-crown-6, dibenzo-18-crown-6, and dibenzo-24-crown-8 and acyclic analogs mono-, di-, tri-, tetra-, penta-, and hexaethylene glycols were studied using FAB mass spectrometry. These cyclic ligands form (M + 117)+, (M + 157)+, (M + 231)+, and (M + 253)+ ions with different aluminum-containing species. Collisionally activated dissociations of these adduct ions gave fragment ions, initially due to the loss of ligands directly attached to aluminum, followed by insertion of aluminum into the remaining ligand skeleton. Further fragmentation of the metal-containing species gave ions corresponding to consecutive losses of C2H4O units. Fragmentations of deuterium-labelled ions were used to help in establishing fragmentation pathways. Selectivity towards metal chelation is observed in this order: 12-crown-4 < 15-crown-5 < 18-crown-6. The elemental compositions of adduct ions were confirmed by high-resolution measurements. The formation of (M + Al − 2H)+ ion, obtained by the displacement of two hydroxy protons, is more favored for tetra- and pentaethylene glycols. Key words: crown ethers, polyethylene glycols, aluminum(III)–glycerol, ionic complexes and ion dissociations.

Complexation of aluminum ions {Al(III) in glycerol} with α-amino acids has been studied by FAB mass spectrometry. Twelve α-amino acids and cysteine methyl ester interact with different Al(III)-containing ions and form several cluster ions such as [M+117]+, [117={A1(III)+glycerol−2H}]; [M+231]+, [231={Al(III)+glycerol+ trifluoroacetic acid−2H}]; [M+233]+, [233={2Al(III)+2glycerol−5H}]; [2M+Al−2H]+ and [2M+117]+. Fragmentation of these adduct ions led to the formation of mainly metal-containing product ions. Fragmentation pathways were demonstrated with the help of the dissociation of Leu-d3, His-d4, Tyr-d4, Ser-d4, Cys-d4 and Cys methyl ester-d3 ion complexes in glycerol-d3. Aliphatic, aromatic and α-amino acids possessing functional side chains show differences in the fragmentation of [M+117]+ ions. Fourteen peptides of different chain lengths (two through six amino acids) also form adducts with Al(III)-glycerol. Dissociation of these complex ions, especially [M+Al−2H]+ ions provides information about side-chain functional groups and some sequence information. The site of the metal-ion interaction is mostly at the amide nitrogens.

The mass spectra of tris(perfluorophenyl)phosphine obtained under negative ion Fast Atom Bombardment conditions showed formation of an unusual ion at m/z 397 attributed to ((C6F5)2PO2)−. The matrix effects involved in this reaction are discussed. Negative ion FAB spectra of tris(perfluorophenyl)arsine and tris(perfluorophenyl)stibine are also reported. Keywords: pentafluorophenylphosphine, -arsine, -stibine; negative ion FABMS; matrix effects.

In this paper we report our studies of reduction phenomena in a high performance liquid chromatography/particle beam interface-mass spectrometer system (HPLC/PB-MS). It is shown that reduction takes place in the ion source of the mass spectrometer, but that the particle beam interface plays an important role in the reduction process since the HPLC mobile phase is involved in the reduction. HPLC flow rate and desolvation-chamber temperature have significant effects on the reduction extent, while ion-source temperature has only a minor effect. All the nitro compounds and sulfoxides tested in this work showed reduction in the system. There was no observed reduction for sulfones. 1,4-Naphthaquinone showed significant reduction, while no reduction was observed for anthraqunone.

The tris(acetylacetonate) (L3) and tris(1,1,1-trifluoromethyl-2,4-pentanedionate) (L′3) complexes of transition metals V, Cr, Mn, Fe, Co, Ru and Os in their +3 oxidation states were studied under fast-atom bombardment (FAB) conditions using 3-nitrobenzyl alcohol as a matrix. All complexes showed the formation of molecular ion and protonated molecules [ML2]+ and [ML′2]+ are the most abundant ions in the spectra of all the metal acetylacetonates (L) and trifluoroacetylacetonates (L′) studied. Interaction of matrix with metal complexes and polynuclear metal complexes led to the formation of polynuclear species with significant abundance especially for manganese and iron complexes. Formation of these metal ions was observed with relative intensities from 3–30%. Ions corresponding to ligand-exchange reactions were observed with moderate to high abundance in all metal complexes studied except those of ruthenium and osmium. Experiments carried out with a split FAB probe tip suggested ligand–ligand exchange reactions were not due to gas-phase reactions but only due to solution-phase exchanges. Osmium and ruthenium complexes do not yield polynuclear species or ions due to matrix clustering. Instead they show neutral ligand losses and formation of acetyl ion.

Various methods of suppression of the reduction process occurring in fast-atom bombardment (FAB) mass spectrometry have been studied, using the organic dyes rhodamine B and methylene blue as reference compounds. Our results indicate that transition metal chlorides have a strong influence on the suppression of the reduction process, while stannous chloride exhibits a remarkable suppression effect despite being a strong reducing agent. We suggest that the metal radicals generated in glycerol solution are responsible for these suppression effects. This phenomenou strongly supports the mechanism of hydrogen radical addition to the substrate molecules, postulated earlier as the cause of the reduction process. Co-solvents in the matrix have also been found to suppress the reduction ions along with other matrix-interfering ions. These studies help shed some light on the FAB ionization mechanism.

The relative metal ion (Ni+, Co+, CoCl+) affinities of twelve alkylamines have been estimated using Cooks' kinetic method in a FAB mass spectrometer. The results are compared with proton affinities and with two-ligand dissociation enthalpies. An approximate ordering for the relative metal ion affinities of the amines is given and discussed. The RNH2-Ni+ bond is found to be slightly weaker than RNH2-CoCl+ but stronger than RNH2-Co+. The effective temperature (T) of the metal-bound dimer ions may fall in the range 298 K ≤ T

In this Communication we report, for the first time, a direct method for the determination of benomyl (methyl [1-(butylcarbamoyl)-1H-benzimidazol-2-yl]carbamate) in wettable powder formulations by fast-atom bombard-ment mass spectrometry (FAB-MS). Solutions of desired concentrations of benomyl were prepared in 5 M hydrochloric acid. The matrix compound, glycerol, was added at 10% (v/v) to these solutions for obtaining FAB mass spectra. The results of the analysis of wettable powder samples, carried out by FAB-MS, compared well (p > 0.05) with those obtained by reversed-phase high performance liquid chromatography.

ZnF2, CdF2, and CuF2 have been adsorbed onto the surface of montmorillonite K10, and the infrared and 19F, 27Al, and 29Si MAS NMR spectra of the resulting reagents over a range of loadings and activation temperatures have been obtained. CuF2 was observed to attack the SiO2 layer and form the complex CuSiF6, ZnF2 tends to attack the aluminium oxide layer, in which Zn isomorphously replaces Al, and forms AlF3 and AlF4− complexes. The spectroscopic evidence rules out the formation of any Al–F and (or) Si–F species as CdF2 is adsorbed on the surface of montmorillonite K10. The reactivity of MF2–K10 reagents towards the Friedel–Crafts reaction of benzene with benzyl chloride varies from one reagent to another. ZnF2–K10 was observed to be the most reactive and CuF2 was the least reactive.

ZnF2, CdF2, and CuF2 have been adsorbed onto the surface of montmorillonite K10, and the infrared and 19F, 27Al, and 29Si MAS NMR spectra of the resulting reagents over a range of loadings and activation temperatures have been obtained. CuF2 was observed to attack the SiO2 layer and form the complex CuSiF6, ZnF2 tends to attack the aluminium oxide layer, in which Zn isomorphously replaces Al, and forms AlF3 and AlF4− complexes. The spectroscopic evidence rules out the formation of any Al–F and (or) Si–F species as CdF2 is adsorbed on the surface of montmorillonite K10. The reactivity of MF2–K10 reagents towards the Friedel–Crafts reaction of benzene with benzyl chloride varies from one reagent to another. ZnF2–K10 was observed to be the most reactive and CuF2 was the least reactive.

The formation of transition-metal ion (M+Fe+, CO+, Ni+ and Mn+) complexes with cyclohexylamine (1) in a modified fast-atom bombardment (FAB) source, and the reactions of various ion/molecule complexes, have been studied by FAB MASS spectrometry combined with metastable ion and collisional activation techniques. Multiples dehydrogenations to produce [(aniline)·M]+ and consecutive [2H2+NH3] elimination to afford [(benzene)·M]+ from 1 prevail for all the metal ions studied. Furthermore, [(1)·][Ni]+ and [(1)2·Co]+ ions underwent an unusual NH3 loss. Relative reactivities of the metal ions and complicated ligand effects are presented.

First field-free region B/E linked scan studies of metastable and particularly collision-induced dissociations show that two competitive coordination processes ("end-on" and "side-on") exist in the complexation of metal ions (Ni+, Co+, Fe+, and Mn+) with alkanenitriles in the FAB source of an E/B configuration mass spectrometer. Analysis of the B/E linked scan CA spectra gives approximate percentages of the end-on coordination mode in the reactive complexes. An unusual β-methyl migration, involved in the elimination of CH4 from end-on complexes, may be in competition with β-H migration/elimination of H2 and β-C—C bond cleavage/elimination of alkene. For the side-on complexes, the metal ions can insert into various C—C bonds followed by β-H transfer/competitive elimination of alkene and alkane or by a direct C—M+ bond cleavage to give an alkyl radical. Key words: FAB mass spectroscopy, metal-ion/nitrile reactions, collisional activation, coordination modes, ion–molecule reactions.

Alkali metal fluorides have been adsorbed onto montmorillonite clay K10, and the resulting reagents analysed by 19F magic angle spinning nuclear magnetic resonance and infrared spectroscopy. The complexes M3SiF6, MAlF4, and M3AlF6 are readily formed, the particular complex depending on M, the loading, and the drying temperature employed. Chemisorption of fluoride to give surface -Si-F groups also occurs under certain conditions. Keywords: MAS NMR, alkali metal fluorides, adsorption, montmorillonite clay, infrared.

Trifluoromethylthiocopper(I) has been readily prepared from the silver analogue, using a metathetical reaction with copper(I) bromide. Homogeneous CuSCF 3 and the supported reagent CuSCF 3 -alumina have been compared in their reactivity towards aryl iodides, in order to form trifluoromethylaryl sulphides in good yields.

The relative CoCI+ ion affinities of six alkylnitriles have been estimated using Cooks' kinetic method in mass spectrometer using fast-atom bombardm ent ionization. An approximate ordering for the relative affinities is given and discussed.

A comprehensive low-resolution study of the mass spectra of the compounds C6F5M(CH3)2, where M = N, P, As, is described, fragmentation pathways being assigned with the aid of normal metastable ions and mass analyzed ion kinetic energy spectra (mikes). A comparison of these spectra has re-affirmed the absence of halogen transfer processes for atoms such as N which are incapable of providing the necessary vacant orbitals apparently prerequisite in the mechanisms. The influence of increased coordination to phosphorus and effects on halogen transfer processes are discussed with respect to the mass spectra of the compounds C6F5PX(CH3)2, X = O, S, Se and the gold adducts C6F5P(CH3)2•AuX, X = Cl, Br, I.

RTeCl3 (R  C6H5, p-CH3OC6H4 or p-C6H5OC6H4) reacts with Me3SiNR′2 (R′2  Et2, C4H8) under dry nitrogen atmosphere to give R(R′N)TeCl2 and Me3- SiCl. The products readily decompose to give (R′2NH2)+(RTeCl4). The prod ucts have been characterized by 1H NMR, IR and mass spectra. R2TeCl2 does not react with Me3SiNR'2 even on refluxing for 6 h. Et2NLi, however, reduces R2TeCl2 to R2Te.

Hydrogen bond assisted C- and O-alkylations, sulphenylations, and Michael additions have been carried out with the aid of fluoride ion immobilized on strongly basic anion exchange resins.

Application of the new fast atom bombardment (FAB) mass spectrometry technique to varous organometallic systems is reviewed and its potential explored briefly, especially with respect to polar or thermally labile systems, and heterogeneous catalysis.

The mass spectra of a number of phospholes and metalloles of general structure 1 and 2 are[Formula: see text]discussed with respect to their fragmentation and ion rearrangement processes. Of special interest is the migration of ring fluorines to the central atom during fragmentation. The bonding principles involved for the postulated intermediates are discussed.

B -Tris(alkylamino)- N -trialkyl-borazines and B -tris(arylamino)- N -triaryl-borazines may be prepared almost quantitatively by employing the appropriate stoichiometry in the reaction between boron trichloride and an alkyl- or aryl-amine. The borazines so formed react with boron trifluoride or boron trifluoride etherate to give good yields of the B -trifluoro- N -trialkyl- and B -trifluoro-N-triaryl-borazines. Using this methods, (CH 3 NBF) 3 , ( p -ClC 6 H 4 NBF) 3 and (C 6 F 5 NBF) 3 have been prepared. The analogous reaction using (C 6 F 5 ) 3 B as a route to B -tris(pentafluorophenyl)borazines was unsuccesful.

Some ion-formation processes during fast atom bombardment (FAB) are discussed, especially the possibility of reactions in the gas phase. Divided (two halves) FAB probe tips were used for introducing two different samples into the source at the same time. Our results showed [M+A] + ions (where M=crown ethers and A=alkali metal ions), can be produced, at least in part, in the gas phase when crown ethers and sources of alkali metal ion are placed on two halves of the FAB probe tip

The direct observation of pre-formed hydrogen bonded fluoride complexes by mass spectrometry has been achieved for the first time by fast atom bombardment of the solid and liquid samples. For a series of substituted phenols hydrogen bonded to fluoride it has been found that the substituents affect the apparent stability of the complexes as measured by the relative intensities of the ion peaks.

The positive ion fast atom bombardment (FAB) mass spectra of a series of group IV organometallic halides, (phenyl)3MCl (M = Ge, Sn, Pb), (phenyl)3PbX (X = Cl, Br, I) and Sn(phenyl)nCl4−n are reported in a sulfolane matrix, and compared to their corresponding EI spectra. The use of other matrix liquids such as glycerol thioglycerol, diamylphenol, 18-crown-6/tetraglyme, and p-nitrophenyloctylether are discussed. Disappointingly FAB, like EI, does not produce significant parent ions for group IV organometallics. The FAB and EI spectra are remarkably similar with one major exception. In EI, the loss of a phenyl is preferred over the loss of a halide, while in FAB the reverse is the case, strongly suggesting that the primary ionization occurs in the condensed phase.

Hexamethylphosphoramide (HMPA) adducts of the type Ph3PbX·HMPA (XCl, Br, I, and NCS), Ph2PbX2·2HMPA (XCl, Br, and I), and Ph2PbX2·HMPA (XBr and I), have been prepared and characterized by infrared, Raman, mass, and 31P nmr spectroscopy. Molecular weight and infrared solution data show that Ph3PbX·HMPA adducts dissociate in benzene, the degree of dissociation being NCS«Cl I-Br>Cl for Ph3PbX·HMPA adducts. Corresponding tin and lead adducts are compared with respect to mode of adduct formation.

Solid compounds of composition SnCl2(CH2BrCOO)2, Ti(CH2BrCOO)4, Zr(CH2BrCOO)4, Th(CH2BrCOO)4, Si2O(CH2BrCOO)6 have been isolated when the respective tetrachlorides are refluxed with excess of monobromoacetic acid. Zirconylchloride forms the compound ZrO(CH2BrCOO)2. CH2BrCOOH in a similar manner. These compounds have been characterized by their elemental analysis, molar conductance and by infrared studies, NMR and FAB mass spectrometry. In solution, the bromoacetate groups readily lost. Their Lewis acid character was established by isolating and characterizing their adducts with organic tertiary bases. Antimony pentachloride, aluminium trichloride and ferric chloride form compounds of composition SbCl2(CH2BrCOO)3, Al(CH2BrCOO)3, FeCl(CH2BrCOO)2 and Fe(CH2BrCOO)3 when refluxed with excess of the solvent and these have been characterized by infrared studies.

The mass spectra of a series of ortho, meta and para substituted isopropyl benzene derivatives have been determined where the second substituent is COOH, C(O)NH2, C(O)C6H5, C(Ph)(=NPh) or CH(Ph)(NHPh). Two bis-isopropylbenzophenones have also been studied. The spectra are characterized by prominent ortho effects which distinguish the ortho derivatives from the meta and para.

Metal complexes containing the ligand 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazatetradecane were synthesized and characterized using electron impact (EI) and fast atom bombardment (FAB). The FAB mass spectra were obtained in positive and negative ion mode. FAB in the positive ion mode proved to be the most successful technique for the identification of these compounds. The majority of the FAB spectra obtained were structurally informative, although not all showed molecular (M+) or quasimolecular ([M + H]+) ions. The fragmentations observed were characteristic of the ligands and the metal, and were interpreted based on the chemical and spectroscopic properties of these compounds. Keywords: FAB mass spectroscopy, tetraazacyclotetradecane complexes.

Reaction of tris(pentafluorophenyl)phosphine with various nucleophiles (DMF, HMPA, HEPA, diethylformamide, hydrazine, UDMH, phenylhydrazine, formamide, and aniline) gave exclusively the replacement of all three para fluorines with the exception of aniline, phenylhydrazine, and formamide which gave mixtures of the mono- and bis-4-substituted phosphines. Sodium bisulphide and various alkoxides led mainly to C—P bond rupture though some alkoxides did under certain conditions give some of the expected substitution product. 19F, 31P, and 1H nmr and mass spectral data are presented.

The fast atom bombardment (FAB) mass spectra of a series of hexamethylphosphoramide (HMPA) adducts of phenyltin(IV) halides [Ph 3 SnX · HMPA (X = Cl, Br, I); Ph 2 SnX 2 · HMPA (X = Br, I); Ph 2 SnX 2 · 2HMPA (X = Br, I)] and phenyllead(IV) halides [Ph 3 PbX · HMPA (X = Cl, Br, I); Ph 2 PbX 2 · HMPA (X = Br, I) and Ph 2 PbX 2 · 2HMPA (X = Cl, Br, I)] in a glycerol/HMPA matrix have been investigated, and compared with their electron impact (EI) spectra. No parent ions are observed in either FAB or EI, but in the FAB spectra there is a much higher proportion of metal-containing ions which also have and HMPA molecule attached. This is the case even in a HMPA-free matrix such as p -nitrophenyloctyl ether (NPOE). The main difference in the FAB spectra is the preferential loss of halide compared to phenyl, the reverse of that observed in the EI spectra. The same trend is observed for the IE and FAB spectra of the uncomplexed organometallics. Diphenyltin dihalide · HMPA adducts in the glycerol/HMPA matrix form Ph 3 Sn species which are absent when NPOE is used as the matrix liquid.

Trimethylamine adducts of the boron trihalides, Me3N•BX3 are shown to react in solution with free boron trihalides BY3 to yield mixed halide adducts such as Me3N•BX2Y. Isotope labelling shows that the B—N bond remains intact and that the reaction proceeds in either direction, i.e. either X or Y may be the heavier halogen. A bridged transition state involving five-coordinate boron is postulated. Only in the case of Me3N•BI3 is an ionic predissociation of a B—X bond indicated by reaction with ionic species. Two adducts do not react in solution without the presence of excess Lewis acid, again indicative of a lack of predissociation. In the gas phase two adducts will scramble their halogens even in the absence of excess acid but these reactions occur via B—N bond cleavage.

Decomposition and side reactions of pentafluorophenylmagnesium bromide and pentafluorophenyllithium, when used in syntheses, have been investigated using GC/MS techniques. Reactions with reagents such as C 6 F 5 X (X = H, F, Cl, Br, I), C 6 F 4 X 2 (X = H, Cl), C 6 F 3 Cl 3 , C 6 H 6 , (C 6 X 5 ) 3 P (X = H, F), (C 6 X 5 ) 3 P=O (X = H, F), (C 6 X 5 )Si(CH 3 ) 3 (X = H, F) and (CH 3 ) 4-n SiCl n , n = 1, 2, in ether or ether/n-hexane were studied. In addition to the principal reaction of synthetic use, namely the replacement of a halogen by a pentafluorophenyl group, two types of side reactions were observed. These were (i) intermolecular loss of LiF via a nucleophilic substitution, and (ii) intramolecular loss of LiF, followed by the addition of either, inorganic salts such as lithium or magnesium halides, or organometal compounds such as organolithium or Grignard reagent present in the system. GC/MS proved to be an ideal method of monitoring such organometallic reaction systems, although it was sometimes not possible to identify byproducts as a particular isomer.

Nucleoside base analogs in which fluoro substituents replace the enolic hydroxy groups of uracil, thymine and cytosine have been prepared. Improved methods for the preparation and isolation of the known 2,4-di-fluoropyrimidine, 2,4-difluoro-6-methylpyrimidine and the new 2,4-difluoro-5-methylpyrimidine, 2-fluoro-4-aminopyrimidine, 4-fluoro-2-aminopyrimidine, and other alkylaminofluoropyrimidines are described.

Two useful but quite different manifestations of strong hydrogen bonding in systems containing NH groups are reported and discussed. The pKa limit for observation of proton–proton HNCH spin-spin coupling in N-methylanilines is shown to be related to the strength of added H-bond electron donors so that Ph3PO, Ph3AsO, and F− in particular are useful reagents for resolving this type of coupling. The mechanism of hydrogen exchange between anilines and water and the role of the added electron donors are discussed. Strong H-bonding between anilines or benzylamines and F− causes pronounced changes in the chemical reactivity of the amine. Results of experiments on the alkylation of these amines using potassium and tetra-n-butylammonium fluorides demonstrate the synthetic utility of this effect.

13C nmr chemical shifts are reported for some aromatic and aliphatic tellurium compounds. For a given organic group, the shift of the C1 atom varies in the order [Formula: see text], as expected from electronegative considerations. The C2 atom experiences an opposite trend while the C3 and C4 atoms of the ring experience smaller changes. The chemical shifts of para-substituted aromatic tellurium compounds do not show additivity of contributions from the substituents.

Gas phase displacement reactions of boron trihalides from their trimethylamine adducts show that the order of acceptor power is: BBr3 > BCl3 > BF3 > 1/2(B2H6). This order agrees with recent theoretical calculations and dipole moment, calorimetric, and infrared measurements on boron trihalide complexes with other reference bases.