Synthesis and X-ray structures of triphenylphosphine–mercury(II) thiosalicylate complexes: novel aggregation processes

Reaction of [HgCl2(PPh3)2] with one equivalent of thiosalicylic acid (tsalH2, HSC6H4CO2H) and excess triethylamine, followed by recrystallisation from dichloromethane–diethyl ether gives the compound [Hg2(tsal)2(PPh3)2] (2). This has a bis(S,O)-chelated mercury centre with a nido-trigonal bipyramidal coodination, with the four oxygens of the two carboxylates also coordinated to a Hg(PPh3)2 moiety. When a reduced quantity of pyridine was used as the base a different crystalline product was isolated. This was characterised as [Hg2(tsal)2(PPh3)2][Hg(tsalH)2] (3), which contains the same [Hg2(tsal)2(PPh3)2] moiety found for 2, co-crystallised with a [Hg(tsalH)2]. The two mercury–thiosalicylate species are connected by means of O–H⋯O hydrogen bonding.