Aurophilicity-Based One-Dimensional Arrays of Gold(I) Phenylene-1,3- and -1,4-dithiolates

Phenylene-1,3-dithiol is converted into a trinuclear gold complex by treatment with 1 equiv of {[(Ph3P)Au]3O}+BF4-.
In the product, the phenylene unit bears one gold thiolate and one di(gold)sulfonium function. These components
aggregate into one-dimensional arrays through head-to-tail aurophilic contacts between the two functions. In the
association process, the Au−S−Au angle of the sulfonium group is opened up to accommodate the incoming gold
atom between its metal centers. A similar mode of aggregation is found for the triply aurated biphenylene-4,4‘-dithiol obtained using the tri(gold)oxonium salt with tri(p-tolyl)phosphine ligands. Probably for steric reasons, in this
oligomerization process, the gold(I) thiolate unit is attached side-on to the digold sulfonium unit with retention of
the small Au−S−Au angle. Under similar reaction conditions, and with the same molar ratio of the components,
phenylene-1,4-dithiol is converted into the bis-sulfonium salt:  1,4-{[(p-Tol)3PAu]2S}2C6H4(BF4)2, the dications of
which also associate into chains. Along the chains, the phenylene spacers alternate with tetranuclear gold clusters
which arise from intimate aggregation of pairs of gold atoms. Together with previous findings, the present results
show that gold thiolate (−SAuL) and digold sulfonium functions [−S(AuL)2+] in proper orientation at an arene unit
(α−ω) can be considered as “soldering” points which can be used for joining up the molecular units into one-dimensional arrays solely through metal−metal contacts, which appear to be operative even against Coulomb
repulsion between cations. The reaction of biphenylene-4,4‘-dithiol with 2 equiv of sodium methoxide and [tri(c-hexyl)phosphine]gold chloride gives only neutral digold dithiolate complex 4 which is not associated owing to the
steric bulk of the tri(c-hexyl)phosphine ligands.