The synthesis and coordination chemistry of sulfenic, thiosulfinic, and thiosulfonic acid anions are reviewed. Different approaches, which yield the platinum(I1) and ruthenium(I1) complexes containing the anionic sulfur(0), sulfur(II), and sulfur(1V) oxid ligands, are described. The oxidative addition of thiosulfinates or N-sulfinyl phthalimides to platinum(0) complexes L2Pt(C2H4) [L = PPh3, 112 PPh2CH2CH2PPh2, 1/2 (R,R)-( -1-DIOP, 1/2 (C5H4PPh2)Fe(C5H4PPh2) leads to sulfenato complexes; those of N-thiosulfinyl phthalimides or trisulfid 1-oxides afford the thiosulfinato complexes. Moreover, the reactions of CpRu(PPh,)(L)(SH) (L = CO, PPh3) with Nsulfinyl phthalimides forming the thiosulfinato moiety, are reported. The spectroscopic, structural and chemical properties of these complexes are discussed.

A brief overview is presented of the field of organocatalysis using chiral H‐bond donors, chiral Brønsted acids, and chiral counter‐anions (Fig. 1). The role of TADDOLs (=α,α,α′,α′‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanols) as H‐bond donors and the importance of an intramolecular H‐bond for acidity enhancement are discussed. Crystal structures of TADDOLs and of their N‐, S‐, and P‐analogs (Figs. 2 and 3) point the way to proposals of mechanistic models for the action of TADDOLs as organocatalysts (Scheme 1). Simple experimental two‐step procedures for the preparation of the hitherto strongest known TADDOL‐derived acids, the bicyclic phosphoric acids (2 in Scheme 2) and of a phosphoric‐trifluorosulfonic imide (9 in Scheme 4), are disclosed. The mechanism of sulfinamide formation in reactions of TADDAMIN with trifluoro‐sulfonylating reagents is discussed (Scheme 3). pKa Measurements of TADDOLs and analogs in DMSO (reported in the literature; Fig. 5) and in MeO(CH2)2OH/H2O (described herein; Fig. 6) provide information about further possible applications of this type of compounds as strong chiral Brønsted acids in organocatalysis.

Dedicated to Professor Dieter Seebach on the occasion of his 65th birthdayThe title compounds were prepared starting from pyrrolinone 4. Nucleophilic-displacement and ringclosure reactions yielded the dithiolopyrrole 5a, which formed salts with electrophiles (7, 8) as well as with bases. The crystal structure of 5a was determined. Oxidation of the dithioles 5a and 6a led to S(2)-oxides (10a, 11a) and the corresponding S(2)-dioxides (10b, 11b) depending on reaction conditions. The thiosulfinate 10a was converted by a ring-opening/ring-closure reaction sequence to the bicyclic sulfinamide 12. The oxidative addition reactions of [Pt(h 2 -C 2 H 4 ) (PPh 3 ) 2 ] (14) with the disulfides 5a and 13 led to the dithiolatoplatinum(II) complexes 15 and 16, respectively. Complex 16 was characterized structurally. The sulfenato-thiolato complex 17 was synthesized via reaction of 14 with the thiosulfinate 10a. The thiosulfonato Pt II complex 18 was prepared by an oxidative insertion of Pt 0 into the CÀS bond of the corresponding thiosulfonate 10b. Furthermore, complex 18 was characterized by single-crystal X-ray-diffraction studies.

Bei der Oxidation von 3,3,5,5‐Tetraphenyl‐1,2,4‐trithiolan (1) mit m‐Chlorperbenzoesäure entsteht selektiv das 3,3,5,5‐Tetraphenyl‐1,2,4‐trithiolan‐1‐oxid (2). Die Molekülstruktur von 2 wurde durch Röntgenstrukturanalyse bestimmt. Die Oxidation von Octamethyltetrathiadispiro[3.2.3.2]dodecan‐2,9‐dion (3) mit Trifluorperessigsäure bei –50 °C liefert das 5‐Oxid 4. Das Octamethylpentathiadispiro[3.3.3.2]tridecan‐2,9‐dion (5) wird mit m‐Chlorperbenzoesäure bei 0 °C zum 12‐Oxid 6 oxidiert. Das 1‐Oxid 2 reagiert mit zwei Äquivalenten (Ph3P)2Pt(η2‐C2H4) (7) zu einem 1 : 1 Gemisch von (Ph3P)2PtSCPh2S (8) und (Ph3P)2Pt(η2‐Ph2C=S=O) (9).