Catalytic Dehydrogenation of Amine-Boranes using Geminal Phosphino-Boranes

The reaction of the intramolecular frustrated Lewis pair (FLP) tBu2PCH2BPh2 with the amine-boranes NH3·BH3 and Me2NH·BH3 leads to the formation of the corresponding FLP-H2 adducts as well as novel five-membered heterocycles that result from capturing the in situ formed amino-borane by a second equivalent of FLP. The sterically more demanding tBu2PCH2BMes2 does not form such a five-membered heterocycle when reacted with Me2NH·BH3 and its H2 adduct liberates dihydrogen at elevated temperatures, promoting the metal-free catalytic dehydrogenation of amine-boranes.Peer reviewe

New Insights in Frustrated Lewis Pair Chemistry with Azides

The geminal frustrated Lewis pair (FLP) tBu(2)PCH(2)BPh(2) (1) reacts with phenyl-, mesityl-, and tert-butyl azide affording, respectively, six, five, and four-membered rings as isolable products. DFT calculations revealed that the formation of all products proceeds via the six-membered ring structure, which is thermally stable with an N-phenyl group, but rearranges when sterically more encumbered Mes-N-3 and tBu-N-3 are used. The reaction of 1 with Me3Si-N-3 is believed to follow the same course, yet subsequent N-2 elimination occurs to afford a four-membered heterocycle (5), which can be considered as a formal FLP-trimethylsilylnitrene adduct. Compound 5 reacts with hydrochloric acid or tetramethylammonium fluoride and showed frustrated Lewis pair reactivity towards phenylisocyanate.Peer reviewe

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Gold(I) Complexes of the Geminal Phosphinoborane tBu(2)PCH(2)BPh(2)

In this work, we explored the coordination properties of the geminal phosphinoborane tBu(2)PCH(2)BPh(2) (2) toward different gold(I) precursors. The reaction of 2 with an equimolar amount of the sulfur-based complex (Me2S) AuCl resulted in displacement of the SMe2 ligand and formation of linear phosphine gold(I) chloride 3. Using an excess of ligand 2, bisligated complex 4 was formed and showed dynamic behavior at room temperature. Changing the gold(I) metal precursor to the phosphorus-based complex, (Ph3P) AuCl impacted the coordination behavior of ligand 2. Namely, the reaction of ligand 2 with (Ph3P) AuCl led to the heterolytic cleavage of the gold-chloride bond, which is favored over PPh3 ligand displacement. To the best of our knowledge, 2 is the first example of a P/Bambiphilic ligand capable of cleaving the gold-chloride bond. The coordination chemistry of 2 was further analyzed by density functional theory calculations.Peer reviewe

Gold(I) Complexes of the Geminal Phosphinoborane <i>t</i>Bu₂PCH₂BPh₂

In this work, we explored the coordination properties of the geminal phosphinoborane <i>t</i>Bu₂PCH₂BPh₂ (<b>2</b>) toward different gold­(I) precursors. The reaction of <b>2</b> with an equimolar amount of the sulfur-based complex (Me₂S)­AuCl resulted in displacement of the SMe₂ ligand and formation of linear phosphine gold­(I) chloride <b>3</b>. Using an excess of ligand <b>2</b>, bisligated complex <b>4</b> was formed and showed dynamic behavior at room temperature. Changing the gold­(I) metal precursor to the phosphorus-based complex, (Ph₃P)­AuCl impacted the coordination behavior of ligand <b>2</b>. Namely, the reaction of ligand <b>2</b> with (Ph₃P)­AuCl led to the heterolytic cleavage of the gold–chloride bond, which is favored over PPh₃ ligand displacement. To the best of our knowledge, <b>2</b> is the first example of a P/B-ambiphilic ligand capable of cleaving the gold–chloride bond. The coordination chemistry of <b>2</b> was further analyzed by density functional theory calculations

Gold(I) Complexes of the Geminal Phosphinoborane <i>t</i>Bu₂PCH₂BPh₂

In this work, we explored the coordination properties of the geminal phosphinoborane <i>t</i>Bu₂PCH₂BPh₂ (<b>2</b>) toward different gold­(I) precursors. The reaction of <b>2</b> with an equimolar amount of the sulfur-based complex (Me₂S)­AuCl resulted in displacement of the SMe₂ ligand and formation of linear phosphine gold­(I) chloride <b>3</b>. Using an excess of ligand <b>2</b>, bisligated complex <b>4</b> was formed and showed dynamic behavior at room temperature. Changing the gold­(I) metal precursor to the phosphorus-based complex, (Ph₃P)­AuCl impacted the coordination behavior of ligand <b>2</b>. Namely, the reaction of ligand <b>2</b> with (Ph₃P)­AuCl led to the heterolytic cleavage of the gold–chloride bond, which is favored over PPh₃ ligand displacement. To the best of our knowledge, <b>2</b> is the first example of a P/B-ambiphilic ligand capable of cleaving the gold–chloride bond. The coordination chemistry of <b>2</b> was further analyzed by density functional theory calculations

Multi-messenger Observations of a Binary Neutron Star Merger

International audienceOn 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of $\sim 1.7\,{\rm{s}}$ with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of ${40}_{-8}^{+8}$ Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 $\,{M}_{\odot }$. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at $\sim 40\,{\rm{Mpc}}$) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position $\sim 9$ and $\sim 16$ days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta