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The metallo-formate anions, M(CO 2 ) − , M = Ni, Pd, and Pt, were formed by electron-induced CO 2 activation. They were generated by laser vaporization and characterized by a combination of mass spectrometry, anion photoelectron spectroscopy, and theoretical calculations. While neutral transition metal atoms are normally unable to activate CO 2 , the addition of an excess electron to these systems led to the formation of chemisorbed anionic complexes. These are covalently bound, formate-like anions, in which their CO 2 moieties are significantly reduced. In addition, we also found evidence for an unexpectedly attractive interaction between neutral Pd atoms and CO 2 . 

Small roundworms such as Caenorhabditis elegans release chemical signals called ascarosides in order to communicate with other worms of the same species. Using the ascarosides, the worm can tell its friends, for example, how crowded the neighborhood is and whether there is enough food. The ascarosides thus help the worms in the population decide whether the neighborhood is good – meaning they should hang around, eat, and make babies – or whether the neighborhood is bad. If so, the worms should develop into a larval stage specialized for dispersal that will allow them to find a better neighborhood. Roundworms make the ascarosides by attaching a long chemical ‘side chain’ to an ascarylose sugar. Further chemical modifications allow the worms to produce different signals. In general, to signal a good neighborhood, worms attach a structure called an indole group to the ascarosides. To signal a bad neighborhood, worms make the side chain very short. But how does a worm control which ascarosides it makes? Zhou, Wang et al. now show that C. elegans can change the meaning of its chemical message by modifying the ascarosides that it has already produced instead of making new ones from scratch. Specifically, as their neighborhood runs out of food, C. elegans can use an enzyme called ACS-7 to initiate the shortening of the side chains of indole-ascarosides. The worm can thus change a favorable ascaroside signal that causes the worms to group together into an unfavorable ascaroside signal that causes the worms to enter their dispersal stage. Although Zhou, Wang et al. have focused on chemical communication in C. elegans, the findings could easily apply to the many other species of roundworm that produce ascarosides. Knowing how worms communicate will help us to understand how worms respond to their environment. This knowledge could potentially be used to interfere with the lifecycles and survival of parasitic worm species that harm health and crops. 

Abstract We reply to the comment by S. Pan and G. Frenking who challenged our interpretation of the Na⁻:→BH₃dative bond in the recently synthesized NaBH₃⁻cluster. Our conclusion remains the same as that in our original paper (https://doi.org/10.1002/anie.201907089andhttps://doi.org/10.1002/ange.201907089). This conclusion is additionally supported by the energetic pathways and NBO charges calculated at UCCSD and CASMP2(4,4) levels of theory. We also discussed the suitability of the Laplacian of electron density (QTAIM) and Adaptive Natural Density Partitioning (AdNDP) method for bond type assignment. It seems that AdNDP yields more sensible results. This discussion reveals that the complex realm of bonding is full of semantic inconsistencies, and we invite experimentalists and theoreticians to elaborate this topic and find solutions incorporating different views on the dative bond.