Nucleophilic Aromatic Substitution of Bis(pentafluorophenyl)mercury with Various Bulky Nucleophiles and the Structures of [Hg(C6F4X-4)2] (X=cyclo-C5H10N, OCH(CH3)2, OC(CH3)3)

Reactions of bis(pentafluorophenyl)mercury with piperidine, sodium iso-propoxide or sodium tert-butoxide have yielded the corresponding 4-substituted tetrafluorophenylmercurials, [Hg(C₆F₄X-4)₂] (X = cyclo-C₅H₁₀N (1), OCH(CH₃)₂ (2), OC(CH₃)₃)(3) in reasonable yields but the bulkier nucleophiles, cis-2,6-dimethylpiperidine and 2,6-di-iso-propylphenolate (from sodium 2,6-di-iso-propylphenolate) decomposed the mercurial into pentafluorobenzene. Treatment of bis(pentafluorophenyl) mercury with another bulky nucleophile, 2,6-diphenylphenolate (from sodium 2,6-diphenylphenolate), in methanol, resulted in the unexpected formation of [Hg(C₆F₄(OMe)-4)₂] (4). The structures of all the mercurials have linear C-Hg-C stereochemistry with two coplanar aryl rings. Amongst a complex series of supramolecular interactions, Hg center dot center dot center dot O bonding is observed for the alkoxy substituted mercurials but there are no Hg center dot center dot center dot N interactions in the structure of bis(2,3,5,6-tetrafluoro-4-piperidinophenyl) mercury.