Titanium complexes of dialkanolamine ligands: Synthesis and structure

Synthesis of the title compounds, viz. [RN(CH2CH2O)(CHR1CR2R3O)]Ti(OiPr)2 (13–15) and [RN(CH2CH2O)(CHR1CR2R3O)]2Ti (18–28), by the reaction of one ortwo equivalents of the corresponding dialkanolamines RN(CH2CH2OH)(CHR1CR2R3OH) (1–12) with Ti(OiPr)4 is reported. Other routes to [RN(CH2CH2O)(CHR1CR2R3O)]2Ti, such as the reaction of Ti(CH2Ph)4 with dialkanolamine and the reaction of TiCl4(THF)2 with dialkanolamine/Et3N were also tested. Dimeric titanocane 16, [PhCH2N(CH2CH2O)2Ti(OMe)2]2, was obtained from the reaction of one equivalentof dialkanolamine 3 with CpTi(OMe)3. PhCH2N(CH2CH2O)2Ti(OMenth)2 (17) was prepared from the transalkoxylation reaction of 15 with two equivalents of menthol. The composition and structures of all novel compounds were established by 1H and 13C NMR spectroscopy as well as elemental analysis data. The possible solution structure features of 13–28 are discussed. The single-crystal X-ray diffraction study oftitanocane 16 clearly indicates a dimeric structure for this compound in the solid state. According to X-ray data, compounds [PhCH2N(CH2CH2O)2]2Ti (19), [MeN(CH2CH2O)(CH2CHPhO)]2Ti (20), [MeN(CH2CH2O)(CH2CPh2O)]2Ti (23), erythro-[MeN(CH2CH2O)(CHPhCHPhO)]2Ti (24), threo-[MeN(CH2CH2O)(CHPhCHPhO)]2Ti (25), and {MeN(CH2CH2O)[CH(CH2)4CHO]}2Ti (27) possess a monomeric structure with a hexacoordinate titanium atom in the solid state. Among them complexes 19, 20, 23, 25, and 27 are characterized by a cis disposition of the nitrogen atoms in the coordination environment of the Ti atom, while nitrogen atoms in 24 occupy trans positions

The transannular interaction germanium-nitrogen in germocanes : the influence of substituents.

The reaction of RN(CH2CH2OH)CHR1CR2R3OH (1–8) with a stoichiometric amount of tetrachloro(bromo)germane leads to the corresponding RN(CH2CH2O)(CHR1CR2R3O)GeHal2 (9–21). Difluorenylgermocane 22 was prepared by treatment of diethoxydifluorenylgermane with N-methyldiethanolamine. Different dialkanolamines were found to be successive precursors of dimethylgermocanes, RN(CH2CH2O)(CHR1CR2R3O)GeMe2 (23–26). The chemical properties of simple and easy to access germocanes RN(CH2CH2O)2GeX2 [X = OH, Br (28), Cl (29)] were studied and the difluoro (27), haloalkoxy (30–32), and dialkoxy (33, 34) derivatives were prepared. The structures of the compounds 16, 20–22, and 26 were confirmed by X-ray diffraction and the structural features in solution of 23 and 26 were studied by NMR spectroscopy (NOEs). The relationship between the nature of substituents at different positions of the germocane skeleton and the strength of the intramolecular Ge ← N bond is discussed

Accessing the strong interaction between Λ baryons and charged kaons with the femtoscopy technique at the LHC

The interaction between Λ baryons and kaons/antikaons is a crucial ingredient for the strangeness S=0 and S=−2 sector of the meson–baryon interaction at low energies. In particular, the ΛK‾ might help in understanding the origin of states such as the Ξ(1620), whose nature and properties are still under debate. Experimental data on Λ–K and Λ–K‾ systems are scarce, leading to large uncertainties and tension between the available theoretical predictions constrained by such data. In this Letter we present the measurements of Λ–K⊕+Λ‾–K− and Λ–K⊕−Λ‾–K+ correlations obtained in the high-multiplicity triggered data sample in pp collisions at s=13 TeV recorded by ALICE at the LHC. The correlation function for both pairs is modeled using the Lednický–Lyuboshits analytical formula and the corresponding scattering parameters are extracted. The Λ–K⊕−Λ‾–K+ correlations show the presence of several structures at relative momenta k⁎ above 200 MeV/c, compatible with the Ω baryon, the Ξ(1690), and Ξ(1820) resonances decaying into Λ–K− pairs. The low k⁎ region in the Λ–K⊕−Λ‾–K+ also exhibits the presence of the Ξ(1620) state, expected to strongly couple to the measured pair. The presented data allow to access the ΛK+ and ΛK− strong interaction with an unprecedented precision and deliver the first experimental observation of the Ξ(1620) decaying into ΛK−

System-size dependence of the hadronic rescattering effect at energies available at the CERN Large Hadron Collider

International audienceThe first measurements of K*(892)0 resonance production as a function of charged-particle multiplicity in Xe-Xe collisions at sNN=5.44 TeV and pp collisions ats=5.02 TeV using the ALICE detector are presented. The resonance is reconstructed at midrapidity (|y| < 0.5) using the hadronic decay channel K*0 →K±π∓. Measurements of transverse-momentum integrated yield, mean transverse-momentum, nuclear modification factor of K*0, and yield ratios of resonance to stable hadron (K*0/K) are compared across different collision systems (pp, p-Pb, Xe-Xe, and Pb-Pb) at similar collision energies to investigate how the production of K*0 resonances depends on the size of the system formed in these collisions. The hadronic rescattering effect is found to be independent of the size of colliding systems and mainly driven by the produced charged-particle multiplicity, which is a proxy of the volume of produced matter at the chemical freeze-out. In addition, the production yields of K*0 in Xe-Xe collisions are utilized to constrain the dependence of the kinetic freeze-out temperature on the system size using the hadron resonance gas–partial chemical equilibrium model