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1. Isolation and reactivity of a gold( i ) hydroxytrifluoroborate complex stabilized by anion-π ⁺ interactions

   https://doi.org/10.1039/D1CC04105C  

   Zhou, Jiliang; Litle, Elishua D.; Gabbaï, François P. (October 2021, Chemical Communications)

   A 9,9-dimethylxanthene-based ligand substituted at the 4- and 5-positions by a phosphine and a xanthylium unit, respectively, has been prepared and converted into an AuCl complex, the structure of which reveals an intramolecular Au–Cl⋯π + interaction. This new ligand platform was also found to support the formation of an unprecedented hydroxytrifluoroborate derivative featuring a “hard/soft” mismatched Au– μ (OH)–BF 3 motif. Despite its surprising stability, this gold hydroxytrifluoroborate complex is a remarkably potent carbophilic catalyst which readily activates alkynes, without activator. 

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2. A cationic gold-fluorenyl complex with a dative Au → C ⁺ bond: synthesis, structure, and carbophilic reactivity

   https://doi.org/10.1039/D2CC05436A  

   Litle, Elishua D.; Gabbaï, François P. (January 2023, Chemical Communications)

   Aiming to study the interaction of gold with the highly Lewis acidic fluorenyl cation, we synthesised ( o -[Ph 2 P(C 6 H 4 )Flu)AuCl(tht)][BF 4 ] ([2][BF 4 ]) and ( o -Ph 2 P(C 6 H 4 )Flu)AuCl 2 (3) (Flu = 9-fluorenyl) and found that the latter could be converted into [( o -Ph 2 P(C 6 H 4 )Flu)AuCl] + ([4] + ) upon treatment with NaBArF 24 (BArF 24 = B(3,5-C 6 H 3 (CF 3 ) 2 ) 4 ). [4] + , which has been isolated as a chloride-bridged dimer, readily catalyses the cycloisomerisation of 2-allyl-2-(2-propynyl)malonate. Computational results show that [4] + possesses a strong Au → C + bond and readily activates enynes. 

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3. Crystal structure of cis -[1,2-bis(diphenylphosphanyl)ethene-κ ² P , P ′]dichloridoplatinum(II) chloroform disolvate: a new polymorph

   https://doi.org/10.1107/S2056989018008836  

   Mugemana, Jimmy; Bender, John; Staples, Richard J.; Biros, Shannon M. (July 2018, Acta Crystallographica Section E Crystallographic Communications)

   The title compound, [PtCl 2 (C 26 H 22 P 2 )]·2CHCl 3 (I), is the third monoclinic polymorph of this platinum(II) complex involving the bidentate ligand cis -1,2-bis(diphenylphosphanyl)ethylene ( cis -dppe) [for the others, see: Oberhauser et al. (1998 a ). Inorg. Chim. Acta , 274 , 143–154, and Oberhauser et al. (1995). Inorg. Chim. Acta , 238 , 35–43]. The structure of compound (I) was solved in the space group P 2 1 / c , with one complex molecule in the asymmetric unit along with two solvate chloroform molecules. The Pt II atom is ligated by two P and two Cl atoms in the equatorial plane and has a perfect square-planar coordination sphere. In the crystal, the complex molecule is linked to the chloroform solvate molecules by C—H...Cl hydrogen bonds and face-on C—Cl...π interactions. There are also weak offset π–π interactions present [intercentroid distances are 3.770 (6) and 4.096 (6) Å], linking the molecules to form supramolecular sheets that lie in the bc plane. 

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4. First detection and analysis of an electronic spectrum of vanadium hydride: The D ⁵ Π –X ⁵ Δ (0,0) band

   https://doi.org/10.1063/5.0105844  

   Varberg, Thomas D. (August 2022, The Journal of Chemical Physics)

   The D 5 Π–X 5 Δ (0,0) band of vanadium hydride at 654 nm has been recorded by laser excitation spectroscopy and represents the first analyzed spectrum of VH in the gas phase. The molecules were generated using a hollow cathode discharge source, with laser-induced fluorescence detected via the D 5 Π–A 5 Π (0,0) transition. All five main (ΔΩ = ΔΛ) subbands were observed as well as several satellite ones, which together create a rather complex and overlapped spectrum covering the region 15 180–15 500 cm −1 . The D 5 Π state displays the effects of three strong local perturbations, which are likely caused by interactions with high vibrational levels of the B 5 Σ − and c 3 Σ − states, identified in a previous multiconfigurational self-consistent field study by Koseki et al. [J. Phys. Chem. A 108, 4707 (2004)]. Molecular constants describing the X 5 Δ, A 5 Π, and D 5 Π states were determined in three separate least-squares fits using effective Hamiltonians written in a Hund’s case (a) basis. The fine structure of the ground state is found to be consistent with its assignment as a σπ 2 δ, 5 Δ electronic state. The fitted values of its first-order spin–orbit and rotational constants in the ground state are [Formula: see text] and B = 5.7579(13) cm −1 , the latter of which yields a bond length of [Formula: see text] Å. This experimental value is in good agreement with previous computational studies of the molecule and fits well within the overall trend of decreasing bond length across the series of 3d transition metal monohydrides. 

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5. Green‐Light‐Driven Reductive Elimination of Chlorine from a Carbene‐Xanthylium Gold(III) Complex

   https://doi.org/10.1002/anie.202206265  

   Park, Gyeongjin; Karimi, Mohammadjavad; Liu, Wei‐Chun; Gabbaï, François P. (June 2022, Angewandte Chemie International Edition)

   Abstract With the discovery of late transition metal platforms that support clean photoreductive halogen eliminations, we now describe an indazol‐3‐ylidene gold trichloride complex ([7]⁺) decorated at the 4‐position by a xanthylium unit. This orange complex features a low energy band in the visible part of the spectrum, assigned to the charge transfer excitation of the indazol‐3‐ylidene/xanthylium donor/acceptor dyad. Green‐light irradiation of this complex in the presence of a chlorine trap elicits the clean photoelimination of chlorine radicals, producing the corresponding gold(I) complex. This visible‐light‐induced photoreduction is very efficient, reaching quantum yields close to 10 %. A neutral analog of [7]⁺featuring an anthryl group rather than a xanthylium unit proved to be perfectly photostable, supporting the importance of the xanthylium‐based photoredox unit present in [7]⁺. 

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