Structure of [(1,2-η2)-1,3,5,7-cycloheptatetraene]bis(triphenylphosphine)platinum(0)

The Antiaromatic Nucleophilic Substitution Reaction (SNAAr) in Cycloheptatrienyl-Anion Containing Zwitterions with a Möbius-Aromatic Intermediate

Antiaromatic nucleophilic substitution reactions in cycloheptatrienide pyridinium and phosphonium zwitterions with initial formation of a cycloheptatetraene intermediate are explored. The mechanism was supported by quantum chemical calculations, first-order reaction kinetics, and high-resolution mass spectrometry. The pyridinium zwitterion exhibited weak antiaromaticity, whereas the intermediate displayed Möbius aromaticity, as evidenced by nuclear independent chemical shift values and the shape of its HOMO. This study represents the eighth confirmed instance of a Möbius-aromatic organic species in its ground state.

Oxidation, Coordination, and Nickel-Mediated Deconstruction of a Highly Electron-Rich Diboron Analogue of 1,3,5-Hexatriene

The reductive coupling of an N-heterocyclic carbene (NHC) stabilized (dibromo)vinylborane yields a 1,2-divinyldiborene, which, although isoelectronic to a 1,3,5-triene, displays no extended π conjugation because of twisting of the C2 B2 C2 chain. While this divinyldiborene coordinates to copper(I) and platinum(0) in an η2 -B2 and η4 -C2 B2 fashion, respectively, it undergoes a complex rearrangement to an η4 -1,3-diborete upon complexation with nickel(0).