Solving the Hydrogen and Lithium Substructure of Poly(triazine imide)/LiCl Using NMR Crystallography

Poly(triazine imide) with incorporated lithium chloride has recently attracted substantial attention due to its photocatalytic activity for water splitting. However, an apparent H/Li disorder prevents the delineation of structure–property relationships, for example, with respect to band‐gap tuning. Herein, we show that through a combination of one‐ and two‐dimensional, multinuclear solid‐state NMR spectroscopy, chemical modelling, automated electron diffraction tomography, and an analysis based on X‐ray pair distribution functions, it is finally possible to resolve the H/Li substructure. In each cavity, one hydrogen atom is bound to a bridging nitrogen atom, while a second one protonates a triazine ring. The two lithium ions within each cavity are positioned between two nitrogen atoms of neighbouring triazine rings. The thereby induced local dipole moments cause slight buckling of the framework and lateral displacements of the Cl^? ions at a coherence length below 2 nm. Nevertheless, the average structure conforms to space group P2₁2₁2₁. In this way, we demonstrate that, in particular, the above‐mentioned techniques allow for smart interplay in delineating the real structure of PTI/LiCl.     

Iodine(III)-Promoted Intermolecular Diamination of Alkenes

A rapid and productive vicinal diamination of alkenes takes place in the presence of a hypervalent iodine(III) reagent and bissulfonimides as nitrogen sources. A total of more than 60 examples are presented. The reaction is characterized by its robustness and its wide substrate scope: it proceeds selectively with both terminal and internal alkenes and tolerates a range of functional groups.     

Defined Palladium–Phthalimidato Catalysts for Improved Oxidative Amination

New palladium(II)–phthalimidato complexes have been synthesized, isolated, and structurally characterized. As demonstrated from over 30 examples, they constitute superior catalysts for oxidative amination reactions of alkenes with phthalimide as the nitrogen source. This work streamlines vicinal difunctionalization of alkenes and provides access to significantly improved and experimentally simplified synthetic protocols.     

Intramolecular Tetrylene Lewis Adducts: Synthesis and Reactivity

A series of benzyl(diphenylphosphino) and o‐phenyl(diphenlyphosphino) substituted germylenes and plumbylenes were synthesized by nucleophilic substitution between the respective lithium reagent and tetrylene halide. The Lewis pairs were characterized by X‐ray crystallography and NMR spectroscopy. The reactivity of the tetrylenes was investigated with respect to azide addition. In the germylene case, the germaniumimide was formed as the kinetically controlled product, which rearranges upon heating to give the phosphinimide. The stannylene and plumbylene derivatives react with adamantylazide to give the azide adducts. 1‐Pentene reacts diastereoselectively with the phosphagermirane to give a cyclic addition product. Trimethysilylacetylene shows an addition with the benzylphosphino‐substituted germylene and plumbylene to give the cycloheteropentene molecules. The addition product between phenylacetylene and the four membered Ge‐P adduct shows after addition at room temperature a 1,4‐phenylmigration to give a cyclic phosphine. Alkylnitrene insertion into a Ge?C bond of the alkyne addition product of the phosphagermirane was found in reaction with adamantylazide.     

DFT Rationalization of the Diverse Outcomes of the Iodine(III)‐Mediated Oxidative Amination of Alkenes

A computational study of the mechanism for the iodine(III)‐mediated oxidative amination of alkenes explains the experimentally observed substrate dependence on product distribution. Calculations with the M06 functional have been carried out on the reaction between PhI(N(SO₂Me)₂)₂ and three different representative substrates: styrene, α‐methylstyrene, and (E)‐methylstilbene. All reactions start with electrophilic attack by a cationic PhI(N(SO₂Me)₂)⁺ unit on the double bond, and formation of an intermediate with a single C?I bond and a planar sp² carbocationic center. The major path, leading to 1,2‐diamination, proceeds through a mechanism in which the bissulfonimide initially adds to the alkene through an oxygen atom of one sulfonyl group. This behavior is now corroborated by experimental evidence. An alternative path, leading to an allylic amination product, takes place through deprotonation at an allylic C?H position in the common intermediate. The regioselectivity of this amination depends on the availability of the resonant structures of an alternate carbocationic intermediate. Only in cases where a high electronic delocalization is possible, as in (E)‐methylstilbene, does the allylic amination occur without migration of the double bond.