The Reality of Neandertal Symbolic Behavior at the Grotte du Renne, Arcy-sur-Cure, France

The question of whether symbolically mediated behavior is exclusive to modern humans or shared with anatomically archaic populations such as the Neandertals is hotly debated. At the Grotte du Renne, Arcy-sur-Cure, France, the Châtelperronian levels contain Neandertal remains and large numbers of personal ornaments, decorated bone tools and colorants, but it has been suggested that this association reflects intrusion of the symbolic artifacts from the overlying Protoaurignacian and/or of the Neandertal remains from the underlying Mousterian

Mechanochemical Influence on the Stereoselectivity of Halide Metathesis: Synthesis of Group 15 Tris(allyl) Complexes

The stereochemical outcomes of reactions conducted in solution and those under mechanochemical conditions need not be the same; this is a well-established observation in organic synthesis, but few examples are known in organometallic systems. Halide metathesis is now shown to be a type of mechanochemical reaction that can produce different ratios of stereoisomers depending on whether the reagents are dissolved or ball-milled. Trihalides of As (X = I), Sb (X = Cl), and Bi (X = Cl) react with K­[A′] (A′ = 1,3-(SiMe₃)₂C₃H₃) (As, Sb) or [AlA′₃] (Bi) to generate the tris­(allyl) complexes [EA′₃]. All three complexes are found in two diastereomeric forms of <i>C</i>₁ (<i>R</i>,<i>S</i>,<i>S</i>) and <i>C</i>₃ (<i>R</i>,<i>R</i>,<i>R</i>) symmetry, and mechanochemical synthesis increases the <i>C</i>₁:<i>C</i>₃ ratio relative to that produced in hexanes solution (up to 3.3× in the case of [AsA′₃]). The stereoselectivity of the metathesis in the solid state can be correlated with the asymmetric environment found in the group 15 trihalides; mechanochemical induction provides a new tool for influencing this important class of synthetic reactions