Underlining the Non-Covalent Interactions and Spectral Properties of a New Trimeric Perfluoro-Ortho-Phenylenemercury Supramolecular Complex: Synthesis, Structure and Spectroscopy of [(o-C6F4Hg)3·μ3-TCNB

Abstract

With its close proximity of Hg(II) atoms, elevated electron-withdrawing properties and accessibility to electrophilic sites on its molecular surface, cyclic trimeric perfluoro-ortho-phenylenemercury (o-(C6F4Hg)3) has been identified as one of the simplest Lewis acids. Given the marrying of these effects within the molecule, it has consistently demonstrated facility in forming supramolecular complexes with both neutral and anionic substrates. In an effort to expand the library of neutral substrates complexed by (o-C6F4Hg)3, in this communication we highlight the structural and spectroscopic properties of the complex between (o-C6F4Hg)3 and the organic acceptor TCNB (TCNB = 1,2,4,5-tetracyanobenzene). The supramolecular complex crystallized in the centrosymmetric triclinic space group $$ P\bar{1} $$ and exhibited unit cell dimensions of a = 10.9026(8) A, b = 11.1731(8) A, c = 14.0657(10) A, α = 89.839(6)°, β = 77.893(7)° and γ = 69.328(8)° for the title complex. Close inspection of the solid state structure revealed one-dimensional chains of non-covalent Hg···N interactions between the mercury atoms of (o-C6F4Hg)3 and the nitrogen atoms from nitrile groups lying trans to one another within the organic acceptor. A network of hydrogen bonding interactions between (o-C6F4Hg)3 and TCNB as well as among dimers of TCNB was also observed. Infrared spectroscopic measurements were also completed and revealed a shifting of the nitrile vibrational frequency for TCNB relative to that for the free molecule. Herein we present the structure and infrared spectroscopic properties of the supramolecular complex [(o-C6F4)3·μ3-TCNB], which couples the Lewis Acid trimeric perfluoro-ortho-phenylenemercury ((o-C6F4Hg)3) with the organocyanide acceptor TCNB (TCNB = 1,2,4,5-tetracyanobenzene). .