TRANSITION-METAL COMPLEXES WITH SULFUR LIGANDS .45. MODEL REACTIONS FOR OXIDOREDUCTASES WITH METAL SULFUR CENTERS - PROTON-INDUCED PPH3/HCL EXCHANGE IN [RU(PPH3)2(L)] AND PROPERTIES OF THE RESULTING HCL COMPLEXES [RU(CLH)(PPH3)(L)] (L = 1,2-BIS((2-MERCAPTOPHENYL)THIO)ETHANATO(2-) - 1,2-BIS((3,5-DI-TERT-BUTYL-2-MERCAPTOPHENYL)THIO)ETHANATO(2-))

The ruthenium(II) complexes [Ru(PPh3)2(buS4)] (1) and [Ru(PPh3)2(S4)] (3) (buS42−= l,2-bis((3,5-di-tert-butyl-2-mercaptophenyl)thio)ethanato(2−); S42−= l,2-bis((2-mercaptophenyl)thio)ethanato(2−)) react with gaseous HC1 yielding the HC1 complexes [Ru(ClH)(PPh3)(buS4)] (2) and [Ru(ClH)(PPh3)(S4)] (4), respectively. Monitoring the reactions by1H and31P NMR spectroscopy yields evidence that the first step is a protonation of thiolato S atoms and the second step loss of one PPh3ligand. The protons in 2 and 4 exchange for deuterium when 2 or 4 are treated with CD3OD/DCl. Reacting 4 with CH3I leads to [Ru(Cl)−(PPh3)(S4−Me2)]I (5). The HC1 unit in 2 or 4 is extremely labile toward substitution. When reacted with CO, 4 forms [Ru(CO)(PPh3)(S4)] (7); with N2as well as N20, however, paramagnetic [Ru(Cl)(PPh3)(S4)] (6) is obtained. 4 reacts also with NEt4N3in CH2C12, yielding a mixture of the cyano and azido complexes [Ru(CN)(PPh3)(S4-CH2Cl)] (8) and [Ru(N3)-;(PPh3)(S4−CH2Cl)] (9) which contain the chloromethylated S42−ligand. Upon treatment with bases, 4 forms the coordinatively unsaturated [Ru(PPh3)(S4)] (10), having a five-coordinate, 16e configurated Ru center. 10 rapidly reacts with CO, PMe3, SMe2, SPhMe, and SPh2, yielding the 18e complexes 7, [Ru(PMe3)(PPh3)(S4)] (11), [Ru(SMe2)(PPh3)(S4)] (12), (Ru(SPhMe)-(PPh3)(S4)] (13), and [Ru(SPh2)(PPh3)(S4)] (14). Mechanisms for these reactions are suggested showing that protonation of thiolato atoms and deprotonation of thiol functions, respectively, allow the Ru centers to differentiate between hard and soft substrates as Cl−or, e.g., CO or SMe2. The relevance of these reactions for H+-coupled substrate conversions catalyzed by oxidoreductases will be discussed. © 1990, American Chemical Society. All rights reserved.