Carotenoids are reported to have immunological effects independent of vitamin A activity. Although antioxidant activity has been suggested as a basis of action, the ability of carotenoids to autoxidize to numerous non-vitamin A products with immunological activity is an alternative yet to be fully explored. We have undertaken a systematic study of β-carotene autoxidation and tested the product mixture for immunological activity. Autoxidation proceeds predominantly by oxygen copolymerization, leading to a defined, reproducible product corresponding to net uptake of almost 8 molar equivalents of oxygen. The product, termed OxC-beta, empirical formula C40H60O15 versus C40H56 for β-carotene, contains more than 30% oxygen (w/w) and 85% β-carotene oxygen copolymers (w/w) as well as minor amounts of many C8−C18 norisoprenoid compounds. No vitamin A or higher molecular weight norisoprenoids are present. The predominance of polymeric products has not been reported previously. The polymer appears to be a less polymerized form of sporopollenin, a biopolymer found in exines of spores and pollen. Autoxidations of lycopene and canthaxanthin show a similar predominance of polymeric products. OxC-beta exhibits immunological activity in a PCR gene expression array, indicating that carotenoid oxidation produces non-vitamin A products with immunomodulatory potential.

Self‐help groups: The aluminatopyrrolyl complexes [{η5‐2,3,4,5‐Me4C4N(AlClMe2)}2Cr] and [{η5‐2,3,4,5‐Me4C4N(AlClMe2)CrMe(μ‐NPh)2AlMe2}{Me3Al(thf)}] self‐activate to give single‐site ethylene polymerization catalysts. The closely related dinuclear chromium(II) complex [{η5‐2,3,4,5‐Me4C4N(AlClMe2)Cr}2(μ‐Me)2] (see picture) is a highly active self‐activating ethylene trimerization catalyst.

Pushing the limits of coordination chemistry: The most weakly coordinated silver complexes of the very weakly coordinating solvents dichloromethane and liquid sulfur dioxide were prepared. Special techniques at low temperatures and the use of weakly coordinating anions allowed structural characterization of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(Cl(2)CH(2))(2)][SbF(6)] (see figure). An investigation of the bonding shows that these complexes are mainly stabilized by electrostatic monopole-dipole interactions.The synthetically useful solvent-free silver(I) salt Ag[Al(pftb)(4)] (pftb=--OC(CF(3))(3)) was prepared by metathesis reaction of Li[Al(pftb)(4)] with Ag[SbF(6)] in liquid SO(2). The solvated complexes [Ag(OSO)][Al(pftb)(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)] were prepared and isolated by special techniques at low temperatures and structurally characterized by single-crystal X-ray diffraction. The SO(2) complexes provide the first examples of coordination of the very weak Lewis base SO(2) to silver(I). The SO(2) molecule in [Ag(OSO)][Al(pftb)(4)] is eta(1)-O coordinated to Ag(+), while the SO(2) ligands in [Ag(OSO)(2/2)][SbF(6)] bridge two Ag(+) ions in an eta(2)-O,O' (trans,trans) manner. [Ag(CH(2)Cl(2))(2)][SbF(6)] contains [Ag(CH(2)Cl(2))(2)](+) ions linked through [SbF(6)](-) ions to give a polymeric structure. The solid-state silver(I) ion affinities (SIA) of SO(2) and CH(2)Cl(2), based on bond lengths and corresponding valence units in the corresponding complexes and tensimetric titrations of Ag[Al(pftb)(4)] and Ag[SbF(6)] with SO(2) vapor, show that SO(2) is a weaker ligand to Ag(+) than the commonly used weakly coordinating solvent CH(2)Cl(2) and indicated that binding strength of SO(2) to silver(I) in the silver(I) salts increases with increasing size of the corresponding counteranion ([Al(pftb)(4)](-)>[SbF(6)](-)). The experimental findings are in good agreement with theoretical gas-phase ligand-binding energies of [Ag(L)(n)](+) (L=SO(2), CH(2)Cl(2); n=1, 2) and solid-state enthalpies obtained from Born-Fajans-Haber cycles by using the volume-based thermodynamics (VBT) approach. Bonding analysis (VB, NBO, MO) of [Ag(L)(n)](+) suggests that these complexes are almost completely stabilized by electrostatic interaction, that is, monopole-dipole interaction, with almost no covalent contribution by electron donation from the ligand orbitals into the vacant 5s orbital of Ag(+). All experimental findings and theoretical considerations demonstrate that SO(2) is less covalently bound to Ag(+) than CH(2)Cl(2) and support the thesis that SO(2) is a polar but non-coordinating solvent towards Ag(+).

It's the crown that does it: The auto‐ionization of [TiF4] has been promoted by complexation with [15]crown‐5 to produce [TiF2([15]crown‐5)][Ti4F18], which contains the new tetrahedral ion [Ti4F18]2− (see picture). The thermodynamics of the [Ti4F18]2− ion relative to the [Ti2F9]− ion in the gas, solution, and solid states were calculated by density functional methods.

We reported previously that the spontaneous oxidation of β-carotene and other carotenoids proceeds predominantly by formation of carotenoid-oxygen copolymers and that β-carotene copolymers exhibit immunological activity, including priming innate immune function and limiting inflammatory processes. Oxidative loss of carotenoids in fruits and vegetables occurs during processing. Here we report evidence for the occurrence of associated analogous copolymer compounds. Geronic acid, an indirect, low molecular weight marker of β-carotene oxidation at ∼2% of β-carotene copolymers, is found to occur in common fresh or dried foods, including carrots, tomatoes, sweet potatoes, paprika, rosehips, seaweeds, and alfalfa, at levels encompassing an approximately thousand-fold range, from low ng/g in fresh foods to μg/g in dried foods. Copolymers isolated from several dried foods reach mg/g levels: comparable to initial carotenoid levels. In vivo biological activity of supplemental β-carotene copolymers has been previously documented at μg/g levels, suggesting that some foods could have related activity.

Breaking up: Reduction of a trivalent titanium complex afforded NN cleavage with formation of TiIV nitride complexes (see structure), which can be converted into silylated derivatives.

The formally Ti(I)/Ti(II) mixed-valence toluene complex {2,5- 1) with an inverse sandwich type of structure has been obtained from the reduction of {2,5-[(C 4 H 3 N)CPh 2 ] 2 [C 4 H 2 N(Me)]}TiCl with potassium in toluene. The bridging molecule of toluene in the paramagnetic 1 shows a visible distortion due to a substantial amount of metal-to-ring back-bonding. Complex 1 was always the only detectable product, even in cases when lower than stoichiometric amounts of reductant were employed. DFT calculations have been carried out to elucidate the electronic structure of the mixed-valence 1 in order to clarify the reason for its apparent thermodynamic stability. The most energetically favorable model comprises two divalent Ti centers connected to an organic radical anion. The olefin adducts {2,5- 3) were obtained from identical reactions carried out in the presence of trans-stilbene. Complexes 2 and 3 may be regarded as the result of the oxidative addition of a transient divalent species to the trans-stilbene molecule. In the case of 2 however, the reaction is accompanied by the cleavage of the C-N bond of the π-bound alkylated pyrrole ring.

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