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CS2 promises easy access to degradable sulfur-rich polymers and insights into how main-group derivatisation affects polymer formation and properties, though its ring-opening copolymerisation is plagued by low linkage selectivity and small-molecule by-products. We demonstrate that a cooperative Cr(III)/K catalyst selectively delivers poly(dithiocarbonates) from CS2 and oxetanes while state-of-the-art strategies produce linkage scrambled polymers and heterocyclic by-products. The formal introduction of sulfur centres into the parent polycarbonates results in a net shift of the polymerisation equilibrium towards, and therefore facilitating, depolymerisation. During copolymerisation however the catalyst enables near quantitative generation of the metastable polymers in high sequence selectivity by limiting the lifetime of alkoxide intermediates. Furthermore, linkage selectivity is key to obtain semi-crystalline materials that can be moulded into self-standing objects. Our report demonstrates the potential of cooperative catalysis to produce previously inaccessible main-group rich materials with beneficial chemical and physical properties

We present the first solid-state structural evidence of mono- and bis(pyridine)chloronium cations. The latter was synthesized from a mixture of pyridine, elemental chlorine and sodium tetrafluoroborate in propionitrile at low temperatures. The mono(pyridine) chloronium cation was realized with the less reactive pentafluoropyridine, using ClF, AsF5, and C5F5N in anhydrous HF. During the course of this study, we also investigated pyridine dichlorine adducts and found a surprising disproportionation reaction of chlorine that depended on the substitutional pattern of the pyridine. Electron richer dimethylpyridine (lutidine) derivatives favor full disproportionation into a positively and a negatively charged chlorine atom which forms a trichloride monoanion, while unsubstituted pyridine forms a 1 : 1 py·Cl2 adduct.

A systematic study of halogenate(I/III) anions with polyatomic ligands is presented. The bis(perfluoro-tert-butoxy) halogenates(I) [X(OC4 F9 )2 ]- , X=Cl, Br, I, of chlorine, bromine, and iodine are prepared as their tetraethylammonium salts and characterized with IR, Raman, and NMR spectroscopic methods, as well as single-crystal X-ray diffraction analyses. Spectroscopical data are supported by quantum-chemical calculations. Additionally, the bonding situation of the species in question are analyzed and discussed. Furthermore, the oxidation to the corresponding halogenate(III) derivatives was studied. For [Br(OC4 F9 )2 ]- , oxidation with elemental fluorine gave [BrF2 (OC4 F9 )2 ]- . Iodide was directly oxidized by ClOC4 F9 to the IIII species [I(OC4 F9 )4 ]- , which is a surprisingly inert anion that might be used as a weakly coordinating anion (WCA) in the future. For [Cl(OC4 F9 )2 ]- , the decomposition products of the synthetic approaches towards a chlorine(III) system were analyzed.

Heteroatom-containing degradable polymers have strong potential as sustainable replacements for petrochemically derived materials. However, to accelerate and broaden their uptake greater structural diversity and new synthetic methodologies are required. Here we report a sequence selective ring-opening terpolymerisation (ROTERP), in which three monomers (A, B, C) are selectively enchained into an (ABA′C)n sequence by a simple lithium catalyst. Degradable poly(ester-alt-ester-alt-trithiocarbonate)s are obtained in a Mn range from 2.35 to 111.20 kDa which are not easily accessible via other polymerisation methodologies. The choice of alkali metal is key to achieve high activity and to control the terpolymer sequence. ROTERP is mechanistically compatible with ring-opening polymerisation (ROP) allowing switchable catalysis for blockpolymer synthesis. The ROTERP demonstrated in this study could be the first example of an entirely new family of sequence selective terpolymerisations.

Instead of monomeric cyclopentadienyl cations, the low-temperature reaction of hexachloro- and hexabromocyclo-pentadiene (C5Cl6 and C5Br6) with powerful Lewis acids SbF5 and AsF5 in SO2ClF yields salts of perhalogenated dications [C10Cl10][Sb3F16]2 and [C10Br10][As2F11]2 which are characterized via single crystal X-ray diffraction and NMR spectroscopy. Additionally, this reactivity is rationalized by quantum-chemical calculations.

Anion binding by receptor molecules is a central field of modern chemistry which impacts areas of catalysis as well as biological and materials chemistry. As binding often requires high chemical stability under aerobic and aqueous conditions for practical applications, carbon-based anion receptors have dominated this field, with main group element analogues receiving far less attention. The recent observation that the air- and moisture-stable amino-cyclophosph(V)azanes of the type [RN(E)P(μ-NR)]2 (E = O, S, Se) can exhibit halide binding that is competitive with topologically related organic receptors (such as squaramides and thioureas) has motivated us here to explore how the binding properties of phosphazane receptors can be enhanced further. Coordination of transition metals by the two P,N metal coordination sites of the phosph(III)azane dimer [(2-py)NHP(μ-NtBu)]2 not only activates the receptor for anion binding (by fixing the optimum exo-exo conformation and polarizing the endocyclic N-H substituents) but also stabilizes the P2N2 ring to hydrolysis and oxidation. We show how the binding properties of these receptors can be modulated by the coordinated metal fragments and that they can bind chloride 1 to 2 orders of magnitude stronger than the related squaramides and thioureas. These features can be utilized in anion transport through phospholipid bilayers under aqueous conditions for which transport can be improved by 1 order of magnitude compared to the previous best phosphazane and thiourea transporters. This study demonstrates how careful design of inorganic systems can result in potent supramolecular functionality, beyond that observed for organic counterparts.

We present the synthesis and characterization of the first non-classical Cl(i) polyinterhalide [NMe4][F(ClF)3] as well as the homologous polychloride [NPr3Me][Cl7]. Both salts were obtained from the reaction of the corresponding ammonium chlorides with ClF or Cl2, respectively. Quantum-chemical investigations predict an unexpected planar structure for the [F(ClF)3]− anion., The [F(ClF)3]− anion was synthesized from an organic chloride salt and chlorine monofluoride. Comparison between the [F(ClF)3]− anion and other permutated chlorine fluorine heptahalides reveals the unique effect of a central fluoride ion.

Instead of monomeric cyclopentadienyl cations, the low-temperature reaction of hexachloro- and hexabromocyclo-pentadiene (C5Cl6 and C5Br6) with powerful Lewis acids SbF5 and AsF5 in SO2ClF yields salts of perhalogenated dications [C10Cl10][Sb3F16]2 and [C10Br10][As2F11]2 which are characterized via single crystal X-ray diffraction and NMR spectroscopy. Additionally, this reactivity is rationalized by quantum-chemical calculations.

A facile one‐pot gram‐scale synthesis of tetraalkylammonium tetrafluoridochlorate(III) [cat][ClF4] ([cat]=[NEt3Me]+, [NEt4]+) is described. An acetonitrile solution of the corresponding alkylammonium chloride salt is fluorinated with diluted fluorine at low temperatures. The reaction proceeds via the [ClF2]− anion which is structurally characterized for the first time. The potential application of [ClF4]− salts as fluorinating agents is evaluated by the reaction with diphenyl disulfide, Ph2S2, to pentafluorosulfanyl benzene, PhSF5. The CN moieties in acetonitrile and [B(CN)4]− are transferred in CF3 groups. Exposure of carbon monoxide, CO, leads to the formation of carbonyl fluoride, COF2, and elemental gold is dissolved under the formation of tetrafluoridoaurate [AuF4]−., The synthesis of tetraalkylammonium tetrafluoridochlorate(III) is described. An acetonitrile solution of the alkylammonium chloride salt is reacted with diluted fluorine at low temperature. The application as fluorinating agent is evaluated by the reaction with Ph2S2 to PhSF5, the transformation of the CN moieties in acetonitrile and [B(CN)4]− into CF3, reaction with CO to COF2 and the formation of tetrafluoridoaurate [AuF4]− with elemental gold.

For decades the chemistry of polyhalides was dominated by polyiodides and more recently also by an increasing number of polybromides. However, apart from a few structures containing trichloride anions and a single report on an octachloride dianion, [Cl8 ]2- , polychlorine compounds such as polychloride anions are unknown. Herein, we report on the synthesis and investigation of large polychloride monoanions such as [Cl11 ]- found in [AsPh4 ][Cl11 ], [PPh4 ][Cl11 ], and [PNP][Cl11 ]⋅Cl2 , and [Cl13 ]- obtained in [PNP][Cl13 ]. The polychloride dianion [Cl12 ]2- has been obtained in [NMe3 Ph]2 [Cl12 ]. The novel compounds have been thoroughly characterized by NMR spectroscopy, single-crystal Raman spectroscopy, and single-crystal X-ray diffraction. The assignment of their spectra is supported by molecular and periodic solid-state quantum-chemical calculations.

The formation and experimental characterization of the first hexabromide dianion is presented. This dianion fills the last remaining gap in the series of polybromides from the tribromide [Br3 ]- to the undecabromide [Br11 ]- . The experimental results are compared to quantum-chemical calculations. These calculations predict-based on electrostatic interactions-a T-structure for the hexabromide dianion, while halogen-halogen bonding favors the hockey-stick-like structure experimentally found in the crystal structure. The hexabromide is built of two tribromide moieties, one of which is highly asymmetric. The classification of this unique anion as hexabromide dianion is discussed. The counter ion [C5 H10 N2 Br]+ stabilizes the hexabromide dianion by additional σ-hole interactions. The compound is fully characterized by mass spectrometry, NMR-, IR and single crystal Raman spectroscopies as well as single-crystal X-ray diffraction.

The polybromide salts [BrC(NMe2)2]2[Br8] and [BrC(NMe2)2][Br3] were synthesized in the ionic liquid [BMP][OTf] (1-butyl-1-methyl-pyrrolidinium triflate). The compounds were characterized by Raman, NMR, and X-ray single crystal structure determination as well as quantum-chemical calculations. The polybromide dianion [Br8]2– structure shows similarities to the very recently reported structure of the first octachloride [Cl8]2–.

For decades the chemistry of polyhalides was dominated by polyiodides and more recently also by an increasing number of polybromides. However, apart from a few structures containing trichloride anions and a single report on an octachloride dianion, [Cl

Producción Científica, Although a multitude of studies have explored the coordination chemistry of classical tripodal ligands containing a range of main‐group bridgehead atoms or groups, it is not clear how periodic trends affect ligand character and reactivity within a single ligand family. A case in point is the extensive family of neutral tris‐2‐pyridyl ligands E(2‐py)3 (E=C−R, N, P), which are closely related to archetypal tris‐pyrazolyl borates. With the 6‐methyl substituted ligands E(6‐Me‐2‐py)3 (E=As, Sb, Bi) in hand, the effects of bridgehead modification alone on descending a single group in the periodic table were assessed. The primary influence on coordination behaviour is the increasing Lewis acidity (electropositivity) of the bridgehead atom as Group 15 is descended, which not only modulates the electron density on the pyridyl donor groups but also introduces the potential for anion selective coordination behaviour., 2019-04-04, Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación (AEI), European Social Fund (ESF), Ramón y Cajal contract (RG-R, RYC-2015–19035), The Leverhulme Trust (Grant for DSW and RG-R, postdoctoral fundng for ALC), The Cambridge Trust (Vice Chancellor Scholarship for AJP, Cambridge Australia Scholarship for FJR) , ZEDAT and FU Berlin (PP)

The formation and experimental characterization of the first hexabromide dianion is presented. This dianion fills the last remaining gap in the series of polybromides from the tribromide [Br

The polychloride salt [CCl(NMe2 )2 ](+) 2 [Cl8 ](2-) was synthesized and crystallized in the ionic liquid [BMP]OTf. The compound was fully characterized by Raman spectroscopy as well as X-ray single-crystal structure determination, and represents the first example of a polychloride dianion to be described. Detailed gas-phase and solid-state calculations concerning the nature of the bonding situation were also performed.

Herein we elucidate the interplay of chiral, chelate, solvent, and hydrogen–bonding information in the self-assembly of a series of new three-dimensional metal–organic architectures. Enantiopure ligands, each containing H-bond donors and acceptors, form different structures, depending on the ratio in which they are combined: enantiopure components form M4L4 assemblies, whereas racemic mixtures form M3L3 stacks. Chiral amplification within M3L3 enantiomers was observed when a 2:1 ratio of R and S subcomponent enantiomers was employed. Simply switching the solvent (from MeCN to MeOH) or chelating unit (from bidentate to tridentate) increased the diversity of structures that can be generated from these building blocks, leading to the selective formation of novel M2L2 and M3L2 assemblies. The addition of achiral ligand building blocks resulted in the formation of further structures: When an achiral subcomponent was combined with its R and S chiral congeners, a three-layer heteroleptic architecture was generat...