FAB Mass Spectrometry Research Articles

Isolation and characterization of the major nod factor of Bradyrhizobium japonicum strain 532C

Bradyrhizobium japonicum 532C nodulates soybean effectively under cool Canadian spring conditions and is used in Canadian commercial inoculants. The major lipo-chitooligosaccharide (LCO), bacteria-to-plant signal was characterized by HPLC, FAB-mass spectroscopy MALDI-TOF mass spectroscopy and revealed to be LCO Nod Bj-V (C18:1, MeFuc). This LCO is produced by type I strains of B. japonicum and is therefore unlikely to account for this strains superior ability to nodulate soybean under Canadian conditions. We also found that use of yeast extract mannitol medium gave similar results to that of Bergerson minimal medium.

Stable mononuclear and binuclear ruthenium(II) arene complexes with multiple N-donor poly-pyridyl ligands: synthesis, spectroscopic and structural characterization. Single crystal X-ray structure of [(η 6-C 10H 14)RuCl(bppz)]BF 4

The reaction of 2,3-bis(2-pyridyl)-pyrazine (bppz) with dimeric chloro-bridged arene ruthenium complexes [{(η 6-arene)RuCl 2} 2] (arene= p-cymene or hexamethyl benzene) gives highly stable cationic mono and binuclear complexes with the formulation [(η 6-C 10H 14)RuCl(bppz)] + and [{(η 6-C 10H 14)RuCl} 2(μ-bppz)] 2+. On the contrary, reactions of the potential bridging ligand 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) or 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) with the chloro-bridged dimeric arene ruthenium complexes [{(η 6-arene)RuCl 2} 2] under similar reaction conditions led to the formation of binuclear complexes with the formulation [{(η 6-arene)RuCl} 2(μ-L)] 2+ (where η 6-arene= p-cymene or hexamethyl benzene and L=tptz or bptz). The reaction products were characterized by various physico-chemical techniques, viz. elemental analyses, IR, 1H– 1H COSY, 1H-, 13C-NMR, FAB mass spectroscopy and electronic spectral studies. Molecular structure of the representative mononuclear complex [(η 6-C 10H 14)RuCl(bppz)]BF 4 was determined by single crystal X-ray diffraction analysis. Crystal data: monoclinic, C 2/ c, a=16.103(5) Å, b=16.207(2) Å, c=19.124(2) Å, β=91.61(2)°, Z=8, R=0.0714.

4-Hydroxy-2-nonylquinoline: A Novel Iron Chelator Isolated from a Bacterial Cell Membrane

The membrane associated iron chelator of Pseudomonas aeruginosa has been extracted from membranes of iron-rich cells with ethanol and purified by reverse phase HPLC. Using 13C NMR and FAB mass spectroscopy, the structure of the chelator has been determined to be 4-hydroxy-2-nonylquinoline. This compound has been previously isolated and named pseudan IX, a name which we use here. We synthesized pseudan IX and show that the spectral properties of the synthesized compound and the purified compound are nearly identical. Also purified from the ethanol extract of membranes is 4-hydroxy-2-heptylquinoline, i.e., pseudan VII. Bacterially purified pseudan IX binds iron as indicated by the incorporation of radiolabeled iron into the chelator and by the formation of pink micelles in a concentrated ethanol extract. The formation of pink micelles upon addition of iron to the synthesized compound indicates that it binds iron.

PHOTOCHEMICAL SYNTHESIS OF METAL CARBONYL COMPLEXES OF TETRAALKYLDIPHOSPHINE DISULFIDES, [M2(CO)10(μ-R2P(S)P(S)R2)] (M = Mo, W; R = Me, Et, n-Pr, n-Bu)

The new complexes [M2(CO)10(μ-R2P(S)P(S)R2)] (M = Mo, W; R = Me, Et, n-Pr, n-Bu), (la)–(1d) and (2a)–(2d) [(1a), M = Mo, R = Me; (1b), M = Mo, R = Et; (1c), M = Mo, R = n-Pr; (1d), M = Mo, R = n-Bu; (2a), M = W, R = Me; (2b), M = W, R = Et; (2c), M = W, R = n-Pr; (2d), M = W, R = n-Bu] have been prepared by the photochemical reaction of M(CO)6 with R2P(S)P(S)R2 (R = Me, Et, n-Pr, n-Bu). The complexes have been characterized by elemental analyses, FT-IR and 31P-[1H]-NMR spectroscopy and FAB-mass spectrometry. The spectroscopic studies suggest cis-bridging bidentate coordination of the ligand between the two metals.

Synthesis, properties and spectroscopic studies of rhenium(v) complexes stabilized by tridentate Schiff bases derived from S-methyl dithiocarbazate

Neutral oxorhenium(V) complexes with tridentate SNO Schiff bases have been prepared by substitution reactions on the square pyramidal ionic complex [NBu4][ReVOCl4] and on the six-coordinate rhenium precursor [ReVOCl3(PPh3)2]. The chlororhenium intermediate species [ReVOCl(Ph–SNO–CH3)] 1 allows the formation of the homologous iodo complex [ReVOI(Ph–SNO–CH3)] 2 by a halogen exchange reaction with lithium iodide. The similar complexes [ReVOCl(Ph–SNO–H)] 3 and [ReVOCl(Naph–SNO–H)] 4 have been synthesised using S-methyl-β-N-(2-hydroxyphenylmethylidene)dithiocarbazate (Ph–SNO–H) and S-methyl-β-N-(2-hydroxynaphthylmethylidene)dithiocarbazate (Naph–SNO–H). The ionic complex [NBu4][ReOCl4] reacts with 4 equivalents of PPh3 and Ph–SNO–H or Naph–SNO–H to give rise to the complexes [ReVOCl(Ph–SNO–H)(PPh3)] 5 and [ReVOCl(Naph–SNO–H)(PPh3)] 7 which are smoothly converted in ethanolic solution into [ReVOCl(Ph–SNO–H)(OPPh3)] 6 and [ReVOCl(Naph–SNO–H)(OPPh3)] 8, respectively. Each compound was characterised by elemental analysis, IR, NMR spectra and FAB mass spectrometry. The crystallographic structures of [ReOI(Ph–SNO–CH3)] 2, [ReOCl(Ph–SNO–H)(PPh3)] 5 and [ReOCl(Ph–SNO–H)(OPPh3)] 6 were determined by single crystal X-ray diffraction methods.

Binuclear Co(ii)Co(ii), Co(ii)Co(iii) and Co(iii)Co(iii) complexes of “short” salen homologues derived from the condensation of salicylaldehyde and methanediamine or phenylmethanediamines. Synthesis, structures and magnetismElectronic supplementary information (ESI) available: Appendix, derivation of the expression for the average magnetic susceptibility of a Co(ii)Co(ii) dimer. See http://www.rsc.org/suppdata/dt/b1/b105594c/

Binuclear Co(II)Co(II), Co(II)Co(III) and Co(III)Co(III) complexes are reported of dianionic ligands, L2−, derived from the condensation of two mol of salicylaldehyde, or substituted salicylaldehydes, and one mol of methanediamine or phenyl substituted methanediamines. Direct evidence for the binuclear nature of the compounds is provided by X-ray structural and FAB mass spectroscopy data. Oxidation of the Co(II)Co(II) complexes, [Co2L2], with iodine, in the presence of pyridine, produces two types of compounds depending on the nature of L: mixed valence Co(II)Co(III) dimers of [Co2L2(py)2](I3) stoichiometry, in the case of the phenylmethane derivatives and fully oxidised Co(III)Co(III) dimers, [Co2L2(py)4](I3)2, obtained from the complexes with methanediamine. The crystal structures of [Co2(salben)2(py)2](I3) and [Co2(salmen)2(py)4](I3)2 (salben = N,N′-phenylmethanediyldiphenato, salmen = N,N′-methanediyldiphenato) have been determined. In both dimers the Co atoms are bridged by two bis-bidentate ligands. The coordination geometry of the Co(II) chromophore, CoN2O2, was found to be distorted tetrahedral, as preliminarily suggested by near infrared and room-temperature magnetic susceptibility data. The Co(III) environments, CoO2N4, involving two additional pyridine nitrogens, are regular octahedral. The magnetic behaviour of representative compounds has been determined and discussed.

Properties of some ferrocene macrocyclic dioxotetraamines: the roles of aromatic side-arms

The coordination chemistry and electrochemical behavior of a series of ferrocene macrocyclic dioxotetraamines 1– 4 each of which bears a pendant aromatic group and a malonic diamide fragment in their framework were investigated by electronic absorption spectroscopy and cyclic voltammetry. For the purpose of comparison, their model compounds 5– 8 were also synthesized and studied. The stoichiometry of 1:1 for the complexes has been confirmed by FAB mass spectroscopy and UV–vis titration of Cu(II) ion with ligands 4 and 8. Stability constants for the equilibrium of the above complexes have been evaluated. The ferrocene ligands 1– 4 can electrochemically recognize the transition metal ions (Co 2+, Ni 2+ and Cu 2+), while those ligands with a complexible atom in the side-arm can stabilize selectively the uncommon state of Ni(III).

Electrochemical synthesis and crystal structures of nickel(II), copper(II), zinc(II) and cadmium(II) complexes with N,N′-bis[(4-methylphenyl)sulfonyl]ethylenediamine

The electrochemical oxidation of anodic metal (nickel, copper, zinc and cadmium) in acetonitrile solutions containing N,N′-bis[(4-methylphenyl)sulfonyl]ethylenediamine H2L and an additional nitrogen coligand, such as 1,10-phenanthroline, yielded mixed complexes of general formula [ML(phen)2] (M=Ni, Cu, Zn and Cd). The compounds have been characterized by microanalysis, IR and UV–Vis (Ni, Cu complexes) spectroscopy, FAB mass spectrometry, 1H NMR spectroscopic studies (Zn, Cd complexes) and EPR spectroscopy (Cu and Ni complexes). All compounds have also been characterized by single crystal X-ray diffraction. The molecular structures of these compounds consist of individual monomeric molecules in which the metal atom is in an [MN6] distorted octahedral environment.

Binuclear Gold(I) and Mercury(II) Derivatives of Diethynylfluorenes

A new series of bis(alkynyl) gold(I) and mercury(II) d10 complexes incorporating fluorenyl-based linking units are reported. The binuclear complexes [LAuC⋮CRC⋮CAuL] and their isoelectronic mercury(II) congeners [R‘HgC⋮CRC⋮CHgR‘] (L = tertiary phosphines; R = fluorene-2,7-diyl, dihexylfluorene-2,7-diyl, 9-((ferrocenylphenylene)methylene)fluorene-2,7-diyl, fluoren-9-one-2,7-diyl, 9-(dicyanomethylene)fluorene-2,7-diyl; R‘ = Me, Ph) were prepared in very good yields by the base-catalyzed dehydrohalogenation reaction of the corresponding metal chloride precursors with the appropriate diethynylfluorene derivatives HC⋮CRC⋮CH at room temperature. All the compounds have been fully characterized by FTIR, NMR and electronic absorption spectroscopies and FAB mass spectrometry. The solid-state molecular structures of [Ph3PAuC⋮CRC⋮CAuPPh3] (R = 9,9-dihexylfluorene-2,7-diyl, fluoren-9-one-2,7-diyl) and [MeHgC⋮CRC⋮CHgMe] (R = fluoren-9-one-2,7-diyl) have been determined crystallographically, the last of which represents ...

Highly efficient asymmetric epoxidation of alkenes with a D(4)-symmetric chiral dichlororuthenium(IV) porphyrin catalyst.

A dichlororuthenium(IV) complex of 5,10,15,20-tetrakis[(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,2:5,8-dimethanoanthrance-9-yl]porphyrin, [Ru(IV)(D(4)-Por)Cl(2)] (1), was prepared by heating [Ru(II)(D(4)-Por)(CO)(MeOH)] (2) in refluxing CCl(4). Complex 1 is characterized by (1)H NMR (paramagnetically shifted pyrrolic protons at delta(H) = -52.3 ppm), FAB-mass spectroscopies, and magnetic susceptibility measurement (mu(eff) = 3.1 mu(B)). The ruthenium complex exhibits remarkable catalytic activity toward enantioselective alkene epoxidation using 2,6-dichloropyridine N-oxide (Cl(2)pyNO) as terminal oxidant. The Ru(IV)-catalyzed styrene epoxidation is achieved within 2 h (versus 48 h for the 2-catalyzed reaction), and optically active styrene oxide was obtained in 69% ee and 84% yield (875 turnovers). Likewise, substituted styrenes and some conjugated cis-disubstituted alkenes (e.g., cis-beta-methylstyrene, cis-1-phenyl-3-penten-1-yne, 1,2-dihydronaphthalene, and 2,2-dimethylchromenes) are converted effectively to their organic epoxides in 50-80% ee under the Ru(IV)-catalyzed conditions, and more than 850 turnovers of epoxides have been attained. When subjecting 1 to four repetitive uses by recharging the reaction mixture with Cl(2)pyNO and styrene, styrene oxide was obtained in a total of 2190 turnovers and 69% ee. UV-vis and ESI-mass spectral analysis of the final reaction mixture revealed that a ruthenium-carbonyl species could have been formed during the catalytic reaction, leading to the apparent catalyst deactivation. We prepared a heterogeneous chiral ruthenium porphyrin catalyst by immobilizing 1 into sol-gel matrix. The heterogeneous catalyst is highly active toward asymmetric styrene epoxidation producing styrene oxide in 69% ee with up to 10,800 turnovers being achieved. The loss of activity of the Ru/sol-gel catalyst is ascribed to catalyst leaching and/or deactivation. On the basis of Hammett correlation (rho(+) = -1.62, R = 0.99) and product analysis, a dioxoruthenium(VI) porphyrin intermediate is not favored.

Metal-directed self-assembly of terphenyl based dithiocarbamate ligands

The synthesis of dithiocarbamate ligands based on an m-terphenyl scaffold is reported. These ligands self-assemble with zinc(II), nickel(II) and copper(II) ions to afford neutral, dinuclear metallomacrocycles in varied yields. The assemblies have been characterised by a range of techniques, including 1H NMR, 13C NMR and UV-vis spectroscopy, elemental analysis, mass spectrometry and cyclic voltammetry. Intramolecular coordination of bipyridyl guests has been investigated with the zinc(II) containing macrocycles. NMR spectroscopy and FAB mass spectrometry demonstrate the formation of 1 ∶ 1 inclusion complexes with 4,4′-bipyridyl.

Combinatorial evaluation of the chiral discrimination of permethylated carbohydrates using fast-atom bombardment mass spectrometry

The chiral discrimination abilities of several variously permethylated carbohydrates toward various amino acid 2-propyl esters were combinatorially evaluated from the relative peak intensity of the 1:1 diastereomeric complex ions with the deuterium-labeled l-amino acid 2-propyl ester protonated ion and with the unlabeled d-amino acid 2-propyl ester protonated ions in FAB mass spectrometry. The chiral discrimination abilities evaluated using FAB mass spectrometry approximately corresponded to the ratio of the association constants ( K R / K S ) toward each enantiomer in the solution. Therefore, this evaluation method is very useful for the screening of the chiral discrimination abilities of carbohydrates and their derivatives.

Interaction of metal ions with N-glycosylamines: isolation and characterization of the products of 4,6- O-benzylidene- N-( o-carboxyphenyl)-β- d-glucopyranosylamine with different metal ions

Metal-ion complexes of Li +, Na +, K +, Mg 2+, Ca 2+, Ba 2+, Pb 2+, Cd 2+, Hg 2+ with 4,6- O-benzylidene- N-( o-carboxyphenyl)-β- d-glucopyranosylamine were synthesized and isolated as solid products and characterized by analytical means as well as by spectral techniques, such as, 1H and 13C NMR, FTIR, absorption, FAB mass spectrometry, optical rotation and CD. While the alkali metal ions formed ML type of complexes, the other metal ions formed ML 2 type complexes. Molecular weights of the complexes of Li +, Na + and K + were established based on the molecular-ion peaks in the FAB mass spectra. The saccharide portion remians in the β-anomeric form even after the complexation. The spectral data, as well as the trends observed in the chemical shifts, indicate the interaction preferences between this glycosyl amine and different metal ions, and further reveal certain structural features of the complexes.

Self-assembly with postmodification: kinetically stabilized metalla-supramolecular rectangles.

Interaction of a predesigned molecular "clip" (4) with rigid dipyridyl bridging ligands, in acetone/water mixtures, leads to the formation of molecular rectangles (5-8) in 92-97% isolated yields via spontaneous self-assembly. Characterization was accomplished with multinuclear NMR and UV-vis spectroscopy, FAB mass spectrometry, and X-ray crystallography. The length of these metallamacrocycles ranges from 2 to 3 nm. Postmodification via non-nucleophilic counterion exchange results in enhanced structural integrity for the assemblies.

Group 12 Metal Complexes of 2-Formylpyrrole-(4PL1) and 2-Acetylpyrrole-N(4)-phenylthiosemicarbazone (4Pl2), as Examples form Different Donor Modes. Crystal and Molecular Structures of [Hg(4PL1- H)Br]2 and [Zn(4PL2)2Br2] · 2 EtOH

Abstract The reactions of 4N-phenyl-2-[ 1 -(pyrrol-2-yl)methylidene]-hydrazine carbothioamide (4PL1) and 4N-phenyl-2-[l-(pyrrol-2-yl)ethylidene]-hydrazine carbothioamide (4PL2) with Group 12 metal halides afford complexes of types [M(L)2X2] [M = Zn, L = 4PL1 or 4PL2, X = Cl, Br or I; M = Cd, L = 4PL1, and X = Cl, or L = 4PL2 and X = Cl, Br or I] and [M(L)X2] [M = Cd, L = 4PL1, X = Br or I; M = Hg, L = 4PL1 or 4PL2, X = Cl, Br or I]. The new compounds were characterized by elemental analysis, FAB mass spectrometry, IR spectroscopy, and, in the case of sufficiently soluble compounds, 1H, 13C and, when appropriate, 113Cd or 199Hg NMR spectrometry. The structures of [Hg(4PL1-H)Br] and [Zn(4PL2)2Br2] · 2 EtOH were also studied by single-crystal X-ray diffractometry. In [Hg(4PL1-H)Br] crystallized from the mother liquor of its synthesis, 4PL1 behaves as a monodeprotonated S,N-bidentate ligand. Otherwise, with Hg(II), Zn(II) and Cd(II), 4PL1 and 4PL2 both behave as neutral S-monodentate ligands.

Synthesis and characterisation of N-glycosyl amines from the reaction between 4,6- O-benzylidene- d-glucopyranose and substituted aromatic amines and also between 2-( o-aminophenyl)benzimidazole and pentoses or hexoses

Twelve N-glycosyl amines were synthesised using 4,6- O-benzylidene- d-glucopyranose and different substituted aromatic amines, including some diamines that resulted in bis-glycosyl amines. Another set of six N-glycosyl amines was synthesised using different hexoses and pentoses and 2-( o-aminophenyl)benzimidazole. All compounds were isolated as solid products and purified, their elemental compositions were established, and these were characterised by NMR ( 1H and 13C), UV–Vis, and FTIR spectroscopy, by FAB mass spectrometry (molecular-ion peaks gave molecular weights), and by their optical rotations. While the protected saccharide, 4,6- O-benzylidene- d-glucopyranose, exists as a mixture of β and α anomers in solution, the corresponding N-glycosyl amines were of only the β anomeric form as determined by NMR and FTIR spectroscopy. On the other hand, N-glycosyl amines synthesised from 2-( o-aminophenyl)benzimidazole prefer the α anomeric form, and in two cases a mixture of both the β and the α anomers were observed. The trends observed in the chemical shifts were compared among different products.

Synthesis, Properties, and Ligating Behavior of the First Facultative Tritelluroethers, Te(CH2CH2CH2TeR)2 (R = Me or Ph)

The first examples of linear tritelluroether ligands, Te(CH2CH2CH2TeR)(2) [L, R = Me (LI) or Ph (L-2)], have been prepared from Na2Te and RTeCH2CH2CH2Cl and fully characterized spectroscopically and by quaternization with MeI to the corresponding telluronium. salts, MeITe(CH2CH2CH2TeRMeI)(2). A series of metal complexes have been prepared, the metal substrate being chosen to illustrate the ligating modes available to these ligands and to permit comparison with literature data on complexes of Se(CH2CH2CH2SeMe)(2) and MeC(CH2TeR)(3), In fac-[Mn(CO)3(L)] CF3SO3 the ligands bind as tridentates facially to the metal center, whereas in [PtCl(L)]PF6 the ligands occupy three positions on the square-planar metal center. The [{eta (5)-C5Me5}Rh(L)](PF6)(2) contain tridentate L bound to one triangular face of the octahedron. The X-ray crystal structure of [{eta (5)-C5Me5}Rh(L-2)](PF6)(2). MeOH shows tridentate telluroether coordination with the ligand adopting the DL configuration, giving a distorted pseudo-octahedral environment at Rh(III). A short contact between one C-H group in one of the phenyl rings and the centroid of the other phenyl ring (2.56 Angstrom) helps to stabilize the adopted configuration. The metal complexes have been characterized by analysis, ES+ or FAB mass spectrometry, and IR and multinuclear NMR (H-1, C-13{H-1}, Te-125) spectroscopy. The invertomers present in coordinated L have been established by the multinuclear NMR studies.

Oxidative addition reactions of Rh(SbPh 3) 3(CO)X (X=Cl, Br) with organic phenyl-substituted propargyl compounds. Rhodium(III) phenylpropargyl products and their conversion to rhodiacyclic complexes

Reactions of Rh(SbPh 3) 3(CO)X (X=Cl ( 1), Br ( 2)) with PhCCCH 2Y (Y=OTs, Cl, Br) in CH 2Cl 2 at ambient temperature lead to formation of the oxidative addition products Rh(SbPh 3) 2(CO)X(Y)(η 1-CH 2CCPh) (X=Cl, Y=OTs ( 3), Cl ( 4), Br ( 5); X=Br, Y=OTs ( 6), Br ( 7)). Complexes 3 and 6 each react with pyridine at room temperature to afford the rhodiacyclopent-3-ene-2-ones Rh(SbPh 3) 2(py)X(η 2-C(O)C(Ph)C(OTs)CH 2) (X=Cl ( 8), Br ( 9)). Treatment with AgOTs converts 8 to Rh(SbPh 3) 2(py)(OTs)(η 2-C(O)C(Ph)C(OTs)CH 2) ( 10). Addition of AgOTf (or AgBF 4) and then immediately an excess of PhCCCH 2Br to a CH 2Cl 2 solution of 1 at ambient temperature affords an orange solid that is formulated tentatively as [Rh(SbPh 3) 2(CO)Cl(η 3-CH 2CCPh)]OTf (or BF 4) ( 11a and 11b). All new complexes were characterized by a combination of elemental analysis, FAB mass spectrometry, IR and NMR ( 1H and 13C{ 1H}) spectroscopy and conductance measurements.

The synthesis of triangulo-trimetal complexes containing both iron(II) and vanadium(II)

Reactions between a variety of vanadium(II) and iron(II) starting materials in tetrahydrofuran (thf) solution afforded di-, tri-, and tetra-nuclear complexes containing thf or N, N, N′, N′-tetramethylethylenediamine (tmen) as ligands. Most products were ionic and contained the two metals in different structural units, cation or anion. Trinuclear clusters formulated as [V 3− x Fe x Cl 5(tmen) 3][BPh 4]( x=0–3) were obtained and characterised by C, H, N and metal analyses, 1H NMR, Mössbauer, and positive ion FAB and electrospray mass spectroscopies, and magnetic moment measurements in solution. We characterised fully by low-temperature single-crystal X-ray diffraction analysis the mixed-metal triangulo-complex salt [V 2Fe(μ-Cl) 3(μ 3-Cl) 2(tmen) 3][BPh 4].

Control of the Microarchitecture of a Double Helix − Electrochemical Synthesis and Characterisation of a Novel Dinickel(II) Helicate with Different Groove Sizes

Self-assembly of nickel ions and the N4 Schiff base H2PTs [H2PTs: N,N′-bis(2-tosylaminobenzylidene)-1,3-diaminopropane] in an electrochemical cell leads to the novel neutral double-stranded dinuclear helicate [NiPTs]2·CH3CN (1). Complex 1 was fully characterised by elemental analysis, IR and EPR spectroscopy, FAB mass spectrometry, and magnetic measurements. The single X-ray crystal structure of 1 shows that both ligands are asymmetrically positioned around the Ni−Ni axis, leading to a double-helical complex that presents a major and a minor groove.