Synthesis and Structural Study of Organoantimony(III) and Organobismuth(III) Triflates and Cations Containing O,C,O-Pincer Type Ligands

Utilizing bis(imino)dihydroacridanide pincer ligands in p-block chemistry: synthesis and catalysis of an antimony monocation salt

We present the synthesis and characterization of an Sb(III) monocation salt stabilized by a bulky bis(imino)dihydroacridanide pincer ligand. The Lewis acidity of the Sb cation is quantified using the Guttmann-Beckett method and confirmed by its reaction with 4-dimethylaminopyridine, which forms a Lewis acid-base adduct. This Sb cation exhibits catalytic activity in the cyanosilylation of arylketones. The electronic structure of the Sb cation as well as the mechanism of the catalytic transformation are explored by density functional theory computations.

Catalytic Mechanisms of Transfer Hydrogenation of Azobenzene with Ammonia Borane by Pincer Bismuth Complex: Crucial Role of C=N Functional Group on the Pincer Ligand

Transfer hydrogenation of azobenzene with ammonia borane mediated by pincer bismuth complex 1 was systematically investigated through density functional theory calculations. An unusual metal-ligand cooperation mechanism was disclosed, in which the saturation/regeneration of the C=N functional group on the pincer ligand plays an essential role. The reaction is initiated by the hydrogenation of the C=N bond (saturation) with ammonia borane to afford 3^CN , which is the rate-determining step with Gibbs energy barrier (ΔG^≠ ) and Gibbs reaction energy (ΔG) of 25.6 and -7.3 kcal/mol, respectively. 3^CN is then converted to a Bi-H intermediate through a water-bridged pathway, which is followed up with the transfer hydrogenation of azobenzene to produce the final product N,N'-diphenylhydrazine and regenerate the catalyst. Finally, the catalyst could be improved by substituting the phenyl group for the tert-butyl group on the pincer ligand, where the ΔG^≠ value (rate-determining step) decreases to 24.0 kcal/mol.

Chelating Phosphorus-An O, C, O-Coordinating Pincer-Type Ligand Coordinating PIII and PV Centres

The sequence of reactions of the phosphorus-containing aryllithium compound 5-t-Bu-1,3-[(P(O)(O-i-Pr)₂ ]₂ C₆ H₂ Li (ArLi) with Ph₂ PCl, KMnO₄ , elemental sulfur and elemental selenium, respectively, gave the aryldiphenylphosphane chalcogenides 5-t-Bu-1,3-[(P(O)(O-i-Pr)₂ ]₂ C₆ H₂ P(E)Ph₂ (1, E=O; 2, E=S; 3, E=Se). Compound 1 partially hydrolysed giving [5-t-Bu-1-{(P(O)(O-i-Pr)₂ }-3-{(P(O)(OH)₂ }C₆ H₂ ]P(O)Ph₂ (4). The reaction of ArLi with PhPCl₂ provided the benzoxaphosphaphosphole [1(P), 3(P)-P(O)(O-i-Pr)OPPh-6-t-Bu-4-P(O)(O-i-Pr)₂ ]C₆ H₂ P (5i) as a mixture of the two diastereomers. The oxidation of 5i with elemental sulfur gave the benzoxaphosphaphosphole sulfide [1(P), 3(P)-P(O)(O-i-Pr)OP(S)Ph-6-t-Bu-4-P(O)(O-i-Pr)₂ ]C₆ H₂ (5) as pair of enantiomers P1(R), P3(S)/P1(S), P3(R) of the diastereomer (RS/SR)-5 (5b). The aryldiphenylphosphane 5-t-Bu-1,3-[(P(O)(O-i-Pr)₂ ]₂ C₆ H₂ PPh₂ (6) was obtained from the reaction of the corresponding aryldiphenylphosphane sulfide 2 with either sodium hydride, NaH, or disodium iron tetracarbonyl, Na₂ Fe(CO)₄ . The oxidation of the aryldiphenylphosphane 6 with elemental iodine and subsequent hydrolysis yielded the aryldiphenyldioxaphosphorane 9-t-Bu-2,6-(OH)-4,4-Ph₂ -3,5-O₂ -2,6-P₂ -4λ⁵ -P-[5.3.1.0]-undeca-1(10),7(11),8-triene (7). Both of its diastereomers, (RR/SS)-7 (7a) and (RS/SR)-7 (7b), were separated as their chloroform and i-propanol solvates, 7a⋅2CHCl₃ and 7b⋅i-PrOH, respectively. DFT calculations accompanied the experimental work.

A new C-anionic tripodal ligand 2-{bis(benzothiazolyl)(methoxy)methyl}phenyl and its bismuth complexes

A new tripodal C-anionic ligand, 2-{bis(benzothiazolyl)(methoxy)methyl}phenyl (L), was stably generated by the reaction of the ligand precursor (L'), the corresponding bromide (2-BrC6H4)(MeO)C(C7H4NS)2 (C7H4NS = 2-benzothiazolyl), with nBuLi at -104 °C in the presence of TMEDA (N,N,N',N'-tetramethylethylenediamine). The ligand lithium salt reacted with BiCl3 to give a 2 : 1 complex L2BiCl. A 1 : 1 complex LBiCl2 was obtained in good yield by the redistribution reaction between L2BiCl and BiCl3. X-ray diffraction analysis revealed that the ligand L coordinated in an expected κ3-C,N,N' coordination mode in LBiCl2, while it coordinated in κ3-C,N,O and κ2-C,O coordination modes in L2BiCl. The ligand precursor reacted with BiX3 (X = Cl, Br) to give 1 : 1 complexes L'BiX3 and was found to act as a neutral tripodal C(π),N,N-ligand.

Squeezing Bi: PNP and P2N3 pincer complexes of bismuth

We report the first application of a rigid P2N3 pincer ligand in p-block chemistry by preparing its bismuth complex. We also report the first example of bismuth complexes featuring a flexible PNP pincer ligand, which shows phase-dependent structural dynamics. Highly electrophilic, albeit thermally unstable, Bi(iii) complexes of the PNP ligand were also prepared.

Diverse structure and reactivity of pentamethylcyclopentadienyl antimony(iii) cations

Rare examples of Sb(iii) cations which are not supported by coordinative bonds demonstrate Lewis acidic reactivity.

Neutral and cationic bismuth compounds supported by bis(amidodimethyl)disiloxane ligands

Bis(amidodimethyl)disiloxane ligands derived from O{SiMe₂N(H)R}₂ (abbreviated as (NON^R)H₂) are a stable support for neutral and cationic bismuth compounds. Attempts to extend the series Bi(NON^R)Cl (R = Ar = 2,6-iPr₂C₆H₃; R = tBu) to include compounds where R = Ar' = 2,6-Me₂C₆H₃ were complicated by concomitant formation of the bimetallic compound {Bi(NON^Ar')}₂(μ-NON^Ar'). Compounds containing [Bi(NON^R)]⁺ cations were obtained from reactions with group 13 chlorides MCl₃ (M = Al, Ga). X-ray crystallographic analysis showed intermolecular interactions with the [M_nCl_(3n+1)] anion.

Synthesis and crystal structure of three new bismuth(III) arylsulfonatocarboxylates

Three new bismuth arylsulfonatocarboxylates [Bi(OH)(SB)] (1), [Bi4(ST)2(HST)O2(H2O)2]·H2O (2) and [Bi4(ST)2O3(H2O)2] (3) were synthesized under solvothermal reaction conditions at 180°C using the potassium or sodium salt of 4-sulfobenzoic acid (H2SB) and 2-sulfoterephthalic acid (H3ST), respectively. The compounds were characterized in detail and the crystal structures were determined from single crystal X-ray diffraction data. Phase purity was confirmed by powder X-ray diffraction and elemental analysis. Structural comparisons to the only three other known bismuth sulfonatocarboxylates are presented. Due to the higher reaction temperatures employed for the synthesis of the title compounds a higher degree of condensation of the BiOx polyhedra (X=7 or 8) to tetrameric units, 1D chains or a 2D layer is observed. Connection through the organic linker molecules leads to the formation of 3D coordination polymers in all three title compounds.

Oxine based unsymmetrical (O−, N, S/Se) pincer ligands and their palladium(ii) complexes: synthesis, structural aspects and applications as a catalyst in amine and copper-free Sonogashira coupling

Newly synthesized and characterized (single crystal structure) complexes, [Pd(O⁻, N, S/Se)Cl], efficiently catalyse Sonogashira coupling of ArX at 0.5–1 mol%.

Palladacycles having normal and spiro chelate rings designed from bi- and tridentate ligands with an indole core: structure, synthesis and applications as catalysts

Palladacycles with normal and spiro rings catalyze Suzuki–Miyaura coupling of ArBr/ArCl/allylation of aldehydes at 0.001/1 mol% loading.

Palladacycles of unsymmetrical (N,C−,E) (E = S/Se) pincers based on indole: their synthesis, structure and application in the catalysis of Heck coupling and allylation of aldehydes

Palladacycles of Schiff bases of 1-(2-phenylsulfanyl/selenylethyl)-1H-indole-3-carbaldehyde with benzyl amine catalyze Heck coupling and allylation at 0.1–0.3 and 1.0 mol% respectively.

Antimony(III) and bismuth(III) amides containing pendant N-donor groups--a combined experimental and theoretical study

N,N- and N,N,N-chelated antimony(III) and bismuth(III) chlorides L(1-3)MCl2 1-4 [for L(1): M = Sb (1), for L(2): M = Sb (2) and for L(3): M = Sb (3) and Bi (4)], containing ligands L(1-3) derived from the pyrrole ring (where L(1) = C4H3N-2-(CH[double bond, length as m-dash]N-2',6'-iPr2C6H3), L(2) = C4H2N-2,5-(CH2NMe2)2, L(3) = C4H2N-2,5-(CH2NC4H8)2), were prepared by the treatment of lithium precursors with SbCl3 or BiCl3. Molecular structures 1-4 of were described both in solution (NMR spectroscopy) and in the solid state (single-crystal X-ray diffraction analysis). Structures of 1-4 were also subjected to a density functional theory study.

Synthesis and structure of N,C-chelated organoantimony(v) and organobismuth(v) compounds

The reaction of N,C-intramolecularly coordinated organoantimony(iii) and organobismuth(iii) compounds LMCl2 (M = Sb () or Bi () and L = [o-(CH[double bond, length as m-dash]N-2,6-iPr2C6H3)C6H4]) with phenyllithium in a 1 : 1 or 1 : 2 molar ratio gave compounds LM(Ph)Cl (M = Sb () or Bi ()) and LMPh2 (M = Sb () or Bi ()) in moderate to good yields. Compound could also be prepared by the treatment of the lithium compound LLi with in situ prepared PhSbCl2. Oxidation of the antimony(iii) compounds , and with one equivalent of SO2Cl2 proceeded smoothly with formation of organoantimony(v) compounds LSbCl4 (), LSb(Ph)Cl3 () and LSbPh2Cl2 () in nearly quantitative yields. Compounds are yellowish solids that are stable for a long time even in the presence of air. In contrast, only organobismuth(iii) compounds and could be successfully oxidized using SO2Cl2 to give compounds LBi(Ph)Cl3 () and LBiPh2Cl2 (). Compound is stable, but compound readily decomposed in solution and could not be isolated and stored for a longer period. All attempts to prepare compound LBiCl4 by the oxidation of with SO2Cl2 failed and resulted only in a mixture of products. All studied compounds were characterized by electrospray ionization (ESI) mass spectrometry, and (1)H and (13)C NMR spectroscopy. The molecular structures of , and were unambiguously established using single-crystal X-ray diffraction analysis.

Structural analysis of organometallic compounds with soft ionization mass spectrometry

The analysis of organometallic compounds with mass spectrometry has some special features in comparison with organic and bioorganic compounds. The first step is the choice of a suitable ionization technique, where the electrospray ionization is certainly the best possibility for most classes of organometallic compounds and metal complexes. Some ionization mechanisms of organometallic compounds are comparable to organic molecules, such as protonation/deprotonation, and adduct formation with sodium or potassium ions; however, in many cases, different mechanisms and their combinations complicate the spectra interpretation. Organometallics frequently undergo various types of adduct and polymerization reactions that result in significantly higher masses observed in the spectra in comparison to molecular weights of studied compounds. Metal elements typically have more natural isotopes than common organic elements, which cause characteristic wide distributions of isotopic peaks; for example, tin has ten natural isotopes. The isotopic pattern can be used for the identification of the type and number of metal elements in particular ions. The ionization and fragmentation behavior also depend on the type of metal atom; therefore, our discussion of mass spectra interpretation is divided according to the different type of organometallic compounds. Among various types of mass spectrometers available on the market, trap-based analyzers (linear or spherical ion-traps, Orbitrap) are suitable to study complex fragmentation pathways of organometallic ions and their adducts, whereas high-resolution and high-mass accuracy analyzers (time-of-flight-based analyzers, or Fourier transform-based analyzers-Orbitrap or ion cyclotron resonance mass spectrometers) provide accurate masses applicable for the determination of the elemental composition of individual ions.

Synthesis, Properties Characterization and Applications of Various Organobismuth Compounds

Organobismuth chemistry was emphasized in this review article due to the low price, low toxicity and low radioactivity characteristics of bismuth. As an environmentally-friendly class of organometallic compounds, different types of organobismuth compounds have been used in organic synthesis, catalysis, materials, etc. The synthesis and property characterization of many organobismuth compounds had been summarized. This review article also presented a survey of various applications of organobismuth compounds in organic transformations, as reagents or catalysts. The reactivity, reaction pathways and mechanisms of reactions with organobismuths were discussed. Less common and limiting aspects of organobismuth compounds were also briefly mentioned.

Bismuth(III) 5-sulfosalicylate complexes: structure, solubility and activity against Helicobacter pylori

Treatment of 5-sulfosalicylic acid (H(3)Ssal) with BiPh(3) results in the formation of the first dianionic carboxylate-sulfonate bismuth complex, [PhBi(HSsal)H(2)O](infinity) 1a, and its ethanol analogue [PhBi(HSsal)EtOH](infinity) 1b (space group P2(1)/c), while Bi(OAc)(3) gives the mixed monoanionic and dianionic complex, {[Bi(HSsal)(H(2)Ssal)(H(2)O)(3)](2) x 2 H(2)O}(infinity) 2 (space group P1). The three complexes are all polymeric in the solid state as determined by single crystal X-ray diffraction, with extended frameworks constructed from dimeric [Bi(HSsal)](2), 1a and 1b, or from [Bi(HSsal)(H(2)Ssal)](2) units, 2. The heteroleptic bismuth complexes 1a and 2 display remarkable aqueous solubility, 10 and 2.5 mg ml(-1) respectively, resulting in a clear solution of pH 1.5. In contrast, 1b is essentially insoluble in aqueous environments. All three complexes show significant activity against the bacterium Helicobacter pylori of <6.25 microg ml(-1).