Ferrocene-derivatized dithiophosphonate salts and their gold(I) and palladium(II) complexes

M.Sc.The dimeric structure of Lawesson’s reagent, (RPS2)2 (R = 4–MeOC6H4), or its ferrocenyl analogue (R = ferrocenyl, Fc) leads to symmetrical cleavage through nucleophillic attack by alcohols to form dithiophosphonic acids, which can be readily deprotonated by ammonia to form the corresponding ammonium salts, which can be further reacted with transition-metal halides to form new metal complexes. Among the phosphor-1,1-dithiolates as a generic class of compounds, the dithiophosphates, [S2P(OR)2]-, have been most intensely studied and the dithiophosphonates [S2PR(OR’)]-, the subject of the present study, to a far lesser extent. In this study, a large variety of new dithiophosphonate salts were synthesized from diverse alcohol functionalities derived from cholesterol, estrone, estradiol, pentaerythritol, ethandiol, hydroquinone, resorcinol, glucose and ribose. The salts were oxidized with iodine to yield various S-S oxidative products, of which two X-ray crystal structures of such compounds, the ethandiol and pentaerythritol derivatives, were obtained and they were subjected to further investigation by cyclic voltammetry due to the ferrocenyl-rich functionalities they contain. The reaction of these [S2PR(OR’)]- type salts with a number of gold(I) and palladium(II) precursors, yielded a variety of new complexes. The compounds containing multiple alcohol (hydroxy) sites have been reacted with gold(I) and palladium(II) starting materials ClAu(tht) and PdCl2(PPh3)2, respectively and also with other gold(I) variants, including the mono- and dinuclear phosphines ClAuPPh3, Au2Cl2dppe and Au2Cl2dppa. A new X-ray single crystal structure of a gold(I) complex could be obtained as a decomposition product. New products have been characterized through a combination of solution 1H and 31P NMR, EIS mass spectrometry, IR, elemental analysis, electro-chemistry and single crystal X-ray crystallographic studies