Chirotopic and Stereogenic Metal Centers in [M(L)(L')(‘RS 4 ’)] Complexes with Chiral Thioether‐Thiolate Ligands ‘RS 4 ’‐H 2 [‘MeS 4 ’ 2− = 1,2‐bis(2‐mercaptophenylthio)propanato(2‐), ‘CH 3 (CH 2 ) 2 S 4 ’ 2− = 1,2‐bis(2‐mercaptophenylthio)pentanato(2‐), ‘HO(CH 2 ) 9 S 4 ’ 2− 10

In order to investigate the stereochemistry of substitution reactions of chiral pseudo‐octahedral complexes the chiral thioether‐thiolate ligands ‘RS 4 ’‐H 2 (= HSC 6 H 4 SCHRCH 2 ‐SC 6 H 4 SH) with R = CH 3 ‐ ( 5 ), CH 3 (CH 2 ) 2 ‐ ( 6 ), HO(CH 2 ) 9‐ ( 7 ), and PhCH 2 ‐ ( 8 ) were synthesized by template alkylation of Na 2 [Ni(‘S 2 ’) 2 ] [‘S 2 ’ 2− = 1,2‐benzenedithiolate(2‐)] with 1,2‐dibromoalkanes BrCHRCH 2 Br (R = CH 3 ‐, 1 ; R = CH 3 (CH 2 ) 2 ‐, 2 ; R = HO(CH 2 ) 9 ‐, 3 ; R = PhCH 2 ‐, 4 ) and isolated after hydrolyses. Reactions of ‘RS 4 ’‐H 2 with [RuCl 2 (PPh 3 ) 3 ] or [Mo(O) 2 (acac) 2 ] yielded [Ru(PPh 3 ) 2 (‘RS 4 ’)] (R = CH 3 ‐, 9 ; R = HO(CH 2 ) 9 ‐, 10 ; R = PhCH 2 ‐, 11 ) and [Mo(O) 2 (‘MeS 4 ’)] ( 12 ). [Ru(PPh 3 ) 2 (‘MeS 4 ’)] · 2 CH 2 Cl 2 ( 9 · 2 CH 2 Cl 2 ) and [Mo(O) 2 (‘MeS 4 ’)] ( 12 ) were characterized by X‐ray structure determination. In both complexes, the metal centers are surrounded pseudo‐octahedrally by four sulfur donors of the ‘MeS 4 ’ ligand and two cis coligands. The methyl substituent at the stereogenic C* atom of the C 2 bridge of the ‘MeS 4 ’ ligands assumes an equatorial position. In addition, the metal centers of these complexes are chirotopic and prostereogenic. Crystal data of 9 · 2 CH 2 Cl 2 in comparison with [Ru(PBu 3 ) 2 (‘S 4 ’) 11‐bis(2‐mercaptophenylthio)‐1‐undecanolato(2‐), ‘PhCH 2 S 4 ’ 2− 1,2‐bis(2‐mercaptophenylthio)‐3‐phenylpropanato(2‐)] ] and those of 12 in comparison with [Mo(O) 2 (‘S 4 ’)] show that distances and angles of the coordination cores are not influenced by the substituents on the C 2 bridge. Reactions of the [Ru(PPh 3 ) 2 (‘RS 4 ’)] complexes ( 9–11 ) with the achiral substrates CO and PMe 3 , however, yielded diastereomers of [Ru(PPh 3 )(L)(‘RS 4 ’)] (L = CO, R = CH 3 ‐, 13 ; L = CO, R = HO(CH 2 ) 9 ‐, 14 ; L = CO, R = PhCH 2 ‐, 15 ; L = PMe 3 , R = CH 3 ‐, 16 ; L = PM R = HO(CH 2 ) 9 ‐, 17 ; L = PMe 3 , R = PhCH 2 ‐, 18 ) in diastereomeric excesses between 60 and 82%. The diastereomer of [Ru(PPh 3 )CO)(‘MeS 4 ’)] ( 13 ) which could be characterized by X‐ray structure determination exhibits the CO ligand in trans position to the thioether donor which is bound to the stereogenic C* atom of the C 2 bridge. Reaction of 9 · 2 CH 2 Cl 2 with the optically pure bidentate diphosphine (+)‐(S,S)‐DIOP [= (+)‐2,3‐O‐isopropylidene‐2,3‐dihydroxy‐1,4‐bis(diphenylphosphino)butane] yielded 1:1 mixtures of two diastereomers of [Ru(DIOP)(‘MeS 4 ’)] ( 19 ) one of which was separated in pure form by HPLC.