Nickel complexes / Platinum complexes / S ligands / C-S cleavage / Hydride complexes Nickel and platinum complexes with tridentate ligands, having derivatives (R = Me, Et, Cy) and by replacing a mercaptophenyl unit by an amine in 'Et 2 NS 2 '-H ['Et 2 NS 2 '-H = N,N-diethyl-2-(2-[S 3 ] or [NS 2 ] donor sets were investigated in order to model active sites of enzymes such as hydrogenases or CO mercaptothiophenyl)ethylamine]. Reactions of Ni II or Ni 0 compounds with these ligands in a 1:1 ratio yielded the 1:2 dehydrogenases. Starting from diphenyl sulfide, a preparative synthesis was developed for 'S 3 '-H 2 ['S 3 '-H 2 = bis(2-complexes [Ni('MeS 3 ') 2 ] (7), [Ni('EtS 3 ') 2 ] (9) and [Ni('CyS 3 ') 2 ] (10), with 'RS 3 ' -acting as bidentate ligands only. Complex 7 mercaptophenyl) sulfide]. Reactions of 'S 3 '-H 2 or anionic 'S 3 ' 2- with nickel and platinum precursors resulted in the formation reversibly reacted with PMe 3 to form cis-[Ni(PMe 3 ) 2 ('MeS 3 ') 2 ] (8), exhibiting monodentate 'MeS 3 ' ligands. [Ni('Et 2 HNS 2 ') 2 ]Br 2 of binuclear [Ni('S 3 ')] 2 (1) and trinuclear [Pt('S 3 ')] 3 (5). Complex 1 was cleaved by PMe 3 or CN -to give the mononuclear (11) reacted reversibly with bases to presumably give octahedral [Ni('Et 2 NS 2 ') 2 ]. Complexes 7, 9 and 10 also did not complexes [Ni('S 3 ')(PMe 3 )] (2) and NMe 4 [Ni('S 3 ')(CN)]
(3). Attempts to coordinate hydride to the [Ni('S 3 ')] fragment led to yield any [Ni('RS 3 ')(H)] hydride complex when treated with hydride sources. Oxidative addition of 'CyS 3 '-H to [Pt(PPh 3 ) 4 ] C-S bond cleavage of the ligand and formation of (NMe 4 ) 2 [{Ni(µ-SC 6 H 5 )(S 2 C 6 H 4 )} 2 ] (4). Oxidative addition of yielded the hydride complexes [Pt(H)('CyS 3 ')] and [Pt(H)(PPh 3 )('CyS 3 ')] which, however, formed an inseparable Li['S 3 '-H] to [Pt(PPh 3 ) 4 ] afforded the platinum hydride complexes Li[Pt(H)('S 3 ')] and Li[Pt(H)(PPh 3 )('S 3 ')] which, mixture and underwent C-S bond cleavage when heated, affording [Pt(o-S 2 C 6 H 4 )(PPh 3 ) 2 ]. The molecular structures of 1, however, could not be separated from each other and yielded [Pt('S 3 ')(PPh 3 )] (6) when treated with MeOH. In order to 2, 3, 5, 6, 7, and 11 were determined by X-ray crystallography, revealing butterfly-like shapes for the [MS 3 L] cores of the investigate electronic effects of the donor set, the 'S 3 ' ligand was modified by alkylation of one thiol group to give 'RS 3 '-H complexes. The search for hydrogenase model compounds has reved to be extremely moisture-sensitive and could not yet be Egerlandstr. 1, D-91058 Erlangen, Germany