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1. Structural Evidence for Pnictogen-Centered Lewis Acidity in Cationic Platinum-Stibine Complexes Featuring Pendent Amino or Ammonium Groups

   https://doi.org/10.3390/molecules26071985  

   Rodrigues, Roberta R. ; Gabbaï, François P. ( April 2021 , Molecules)

   null (Ed.)

   As part of our continuing interest in the chemistry of cationic antimony Lewis acids as ligands for late transition metals, we have now investigated the synthesis of platinum complexes featuring a triarylstibine ligand substituted by an o-[(dimethylamino)methyl]phenyl group referred to as ArN. More specifically, we describe the synthesis of the amino stibine ligand Ph2SbArN (L) and its platinum dichloride complex [LPtCl]Cl which exists as a chloride salt and which shows weak coordination of the amino group to the antimony center. We also report the conversion of [LPtCl]Cl into a tricationic complex [LHPt(SMe2)]3+ which has been isolated as a tris-triflate salt after reaction of [LPtCl]Cl with SMe2, HOTf and AgOTf. Finally, we show that [LHPt(SMe2)][OTf]3 acts as a catalyst for the cyclization of 2-allyl-2-(2-propynyl)malonate. 

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2. Synthesis of diphenyl-(2-thienyl)phosphine, its chalcogenide derivatives and a series of novel complexes of lanthanide nitrates and triflates

   https://doi.org/10.1039/d2dt01570f  

   Luster, Troy ; Van de Roovaart, Hannah J. ; Korman, Kyle J. ; Sands, Georgia G. ; Dunn, Kylie M. ; Spyker, Anthony ; Staples, Richard J. ; Biros, Shannon M. ; Bender, John E. ( June 2022 , Dalton Transactions)

   A novel synthesis of diphenyl(2-thienyl)phosphine, along with its’ oxide, sulfide and selenide derivatives, is reported here. These phosphines have been characterized by NMR, IR, MS and X-Ray crystallography. The phosphine oxide derivative was reacted with a selection of lanthanide( iii ) nitrates and triflates, LnX 3 , to give the resultant metal–ligand complexes. These complexes have also been characterized by NMR, IR, MS and X-Ray crystallography. Single crystal X-Ray diffraction data shows a difference in metal–ligand complex stoichiometry and stereochemistry depending on the counteranion (nitrate vs. triflate). The [Ln(Ar 3 PO) 3 (NO 3 ) 3 ] ligand–nitrate complexes are nine-coordinate to the metal in the solid state (bidentate nitrate), featuring a 1 : 3 lanthanide–ligand ratio and bear an overall octahedral arrangement of the six, coordinated ligands. Our [Ln(Ar 3 PO) 3 (NO 3 ) 3 ] ligand–nitrate complexes gave three examples of fac -stereochemistry, where mer -stereochemistry is almost universally observed in the literature of highly related [Ln(Ar 3 PO) 3 (NO 3 ) 3 ] complexes. For the Tb complexes, two different arrangements of the ligands around the metal were observed in the solid state for [Tb(Ar 3 PO) 3 (NO 3 ) 3 ] and [Tb(Ar 3 PO) 4 (OTf) 2 ] [OTf]. [Tb(Ar 3 PO) 3 (NO 3 ) 3 ] is strictly nine-coordinate, ligand mer -stereochemistry in the solid state, and [Tb(Ar 3 PO) 4 (OTf) 2 ] [OTf] is strictly octahedral, six-coordinate, with a square-planar stereochemical arrangement of the phosphine oxide ligands around the metal. 

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3. Selective Separation of Hexachloroplatinate(IV) Dianions Based on Exo‐Binding with Cucurbit[6]uril

   https://doi.org/10.1002/ange.202104646  

   Wu, Huang ; Wang, Yu ; Jones, Leighton O. ; Liu, Wenqi ; Zhang, Long ; Song, Bo ; Chen, Xiao‐Yang ; Stern, Charlotte L. ; Schatz, George C. ; Stoddart, J. Fraser ( June 2021 , Angewandte Chemie)

   The recognition and separation of anions attracts attention from chemists, materials scientists, and engineers. Employing exo‐binding of artificial macrocycles to selectively recognize anions remains a challenge in supramolecular chemistry. We report the instantaneous co‐crystallization and concomitant co‐precipitation between [PtCl₆]²⁻dianions and cucurbit[6]uril, which relies on the selective recognition of these dianions through noncovalent bonding interactions on the outer surface of cucurbit[6]uril. The selective [PtCl₆]²⁻dianion recognition is driven by weak [Pt−Cl⋅⋅⋅H−C] hydrogen bonding and [Pt−Cl⋅⋅⋅C=O] ion–dipole interactions. The synthetic protocol is highly selective. Recognition is not observed in combinations between cucurbit[6]uril and six other Pt‐ and Pd‐ or Rh‐based chloride anions. We also demonstrated that cucurbit[6]uril is able to separate selectively [PtCl₆]²⁻dianions from a mixture of [PtCl₆]²⁻, [PdCl₄]²⁻, and [RhCl₆]³⁻anions. This protocol could be exploited to recover platinum from spent vehicular three‐way catalytic converters and other platinum‐bearing metal waste.

    

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4. Selective Separation of Hexachloroplatinate(IV) Dianions Based on Exo‐Binding with Cucurbit[6]uril

   https://doi.org/10.1002/anie.202104646  

   Wu, Huang ; Wang, Yu ; Jones, Leighton O. ; Liu, Wenqi ; Zhang, Long ; Song, Bo ; Chen, Xiao‐Yang ; Stern, Charlotte L. ; Schatz, George C. ; Stoddart, J. Fraser ( June 2021 , Angewandte Chemie International Edition)

   The recognition and separation of anions attracts attention from chemists, materials scientists, and engineers. Employing exo‐binding of artificial macrocycles to selectively recognize anions remains a challenge in supramolecular chemistry. We report the instantaneous co‐crystallization and concomitant co‐precipitation between [PtCl₆]²⁻dianions and cucurbit[6]uril, which relies on the selective recognition of these dianions through noncovalent bonding interactions on the outer surface of cucurbit[6]uril. The selective [PtCl₆]²⁻dianion recognition is driven by weak [Pt−Cl⋅⋅⋅H−C] hydrogen bonding and [Pt−Cl⋅⋅⋅C=O] ion–dipole interactions. The synthetic protocol is highly selective. Recognition is not observed in combinations between cucurbit[6]uril and six other Pt‐ and Pd‐ or Rh‐based chloride anions. We also demonstrated that cucurbit[6]uril is able to separate selectively [PtCl₆]²⁻dianions from a mixture of [PtCl₆]²⁻, [PdCl₄]²⁻, and [RhCl₆]³⁻anions. This protocol could be exploited to recover platinum from spent vehicular three‐way catalytic converters and other platinum‐bearing metal waste.

    

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5. Benziodoxole-Derived Organosulfonates: The Strongest Hypervalent Iodine Electrophiles and Oxidants

   https://doi.org/10.1055/s-0039-1690761  

   Yusubov, Mekhman S. ; Postnikov, Pavel ; Yoshimura, Akira ; Zhdankin, Viktor V. ( February 2020 , Synlett)

   This account describes the development of organosulfonyloxy-substituted iodine(III) and iodine(V) benziodoxole derived reagents, which are thermally stable compounds with useful reactivity patterns. Iodine(III) benziodoxoles and pseudobenziodoxoles are powerful electrophiles and mild oxidants toward various unsaturated compounds. In particular, pseudocyclic benziodoxole-derived triflate (IBA-OTf) is an efficient reagent for oxidative heteroannulation reactions. Aldoximes react with nitriles in the presence of IBA-OTf at room temperature to give 1,2,4-oxadiazoles in high yields. Moreover, IBA-triflate is used as a catalyst in oxidative heteroannulations with m-chloroperoxybenzoic acid as the terminal oxidant. The iodine(V) benziodoxole derived tosylates, DMP-tosylate and IBX-tosylate, are superior oxidants for the oxidation of structurally diverse, synthetically useful alcohols, utilized as key precursors in the total syntheses of polyketide antibiotics and terpenes. And finally, the most powerful hypervalent iodine(V) oxidant, 2-iodoxybenzoic acid ditriflate (IBX·2HOTf), is prepared by treatment of IBX with trifluoromethanesulfonic acid. According to the X-ray data, the I–OTf bonds in IBX-ditriflate have ionic character, leading to the high reactivity of this reagent in various oxidations. In particular, IBX-ditriflate can oxidize polyfluorinated primary alcohols, which are generally extremely resistant to oxidation. 1 Introduction 2 Iodine(III) Benziodoxole Based Organosulfonates 3 Pseudocyclic Iodine(III) Benziodoxole Triflate (IBA-triflate) 4 Pseudocyclic Iodine(III) Benziodoxole Tosylates 5 Iodine(V) Benziodoxole Derived Tosylates 6 Iodine(V) Benziodoxole Derived Triflate (IBX-ditriflate) 7 Conclusions 

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