Terminally bifurcated tetraaurio-α,ω-bis(sulfonium) salts as building blocks for auriophilicity-determined coordination polymers

Alexander Sladek, Hubert Schmidbaur

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Treatment of α,ω-dithiols HS(CH2)nSH, n = 4 or 5, with tris[(triphenylphosphine)aurio]oxonium tetrafluoroborate affords the corresponding S,S,S′,S′-tetrakis[(triphenylphosphine)aurio]-α,ω- alkanediylbis(sulfonium) bis(tetrafluoroborates) of the type {[(Ph3P)Au]2S(CH2)nS[Au(PPh 3)]2}2+2BF4-. The crystal structure of the species with n = 5 has been determined by single crystal X-ray diffraction studies. In the lattice the unfolded dications are linked into chains through short double Au-Au contacts between the terminal bifurcated diauriosulfonium centers. The analogous reactions with (racemic) 1,2-dithioglycerol and 1,2,3-trithioglycerol also give tri- and tetranuclear complexes with a varying distribution of the metal atoms over the chalcogen(ium) centers. As again demonstrated in a single crystal X-ray diffraction study, the dications {HOCH2HCS[(Ph3P)Au]2CH2S[Au(PPh 3)]2}2+ of the dithioglycerol compound form only dimers through auriophilicity-determined pairing of the bifurcated ends, while the open ends are shielded by the dangling hydroxyl group. The trinuclear complex of 1,2-dithioglycerol is fluxional in solution; the crystal structure has not been determined but is expected to be similar to that derived for the analogous dithioglycol complex. The tetranuclear, trithioglycerol-based dications of {[(Ph3P)-Au]SCH2CHS[Au(PPh3)]CH 2S[Au(PPh3)]2}+BF4 - are isolated in the lattice and feature an unsymmetrical complexation, which is an extension of the structure of the trinuclear dithioglycol analogue {(CH2S)2[Au{PPh3)]3}+ with its strong intramolecular Au-Au contacts. A similar structure is proposed for the monocation {CH2(CH2S)2- [Au(PPh3)]3}+ obtained from propane- 1,3-dithiol. The structures of these cations are also fluxional in solution, however, as shown by variable-temperature NMR studies.

Original languageEnglish
Pages (from-to)3268-3272
Number of pages5
JournalInorganic Chemistry
Issue number11
StatePublished - 1996
Externally publishedYes


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