The X‐ray Crystal Structures of Hg(C6F4X‐p)2 (X = NH2, OMe,or Me) – Two Examples of Supramolecular Lewis Acid/Base Complexes

The X‐ray crystal structures of Hg(C₆F₄X‐p)₂ (X = NH₂, OMe, or Me) show the compounds to have almost linear C–Hg–C stereochemistry (X = NH₂, 176.3(4)°; X = OMe, 179.5(2)°; X = Me, 176.3(2)°), and the two tetrafluoroaryl rings rotated ca. 52–62° with respect to each other. Substantial conjugation of NH₂ and OMe groups with the aromatic rings is evident from N–C and O–C(Ar) distances. For X = NH₂ or OMe, two weak N(O)–Hg coordination interactions per mercury lead to a two dimensional supramolecular chain structure containing pairs of π‐stacked aromatic rings at near van der Waals contact distances rotated at 62.2° (X = NH₂) or 52.9° (X = OMe) to each other. In Hg(C₆F₄Me‐p)₂, which does not have potential donor atoms, no supramolecular structure is obtained, the molecules being laterally displaced from one another.     

Supramolecular Architecture and a New Mode of Pyrazolate Coordination (η3) in the First Homoleptic Lanthanide Pyrazolate Complexes

A linear supramoleculecular array of anions and cations is present in the solvent-free potassium salt of the homoleptic erbium pyrazolate complex [K{Er(η²-tBu₂pz)₄}_n] ( 1 ). Treatment of 1 with [18]crown-6 in toluene/dimethoxyethane leads to formation of a charge-separated salt [Eq. (a)] in which the methyl group of a toluene molecule interacts with the potassium ion. tBu₂pz=3,5-di-tert-butylpyrazolate.