TRANSITION-METAL COMPLEXES WITH SULFUR LIGANDS .95. N2H2, N2H4, NH3, AND N-3- COMPLEXES WITH SULFUR DOMINATED [RU(PPH3)(BUS4)] FRAGMENTS (BUS4(2-) = 1,2-BIS((2-MERCAPTO-3,5-DI-TERT-BUTYLPHENYL)THIO)ETHANATO(2-))

[Ru(ClH)(PPh3) (('bu)S4')] (1) (('bu)S-4('2-) = 1,2-bis((2-mercapto-3,5-di-tert-butylphenyl)thio)ethane(2-)) was obtained by one-pot synthesis from [RuCl2(PPh3)3], ('bu)S4'-Li2, and HCI gas. Elimination of HCI from 1 by reaction with bases gave [Ru(PPh3)(('bu)S4')] (2). 2 formally contains a coordinatively unsaturated Ru center and reacted with Lewis bases such as N3-, NH3, and N2H4, yielding very soluble [Ru(L)(PPh3)(('bu)S4')] complexes (L - N3- (3), NH3 (4), N2H4 (5)). Oxidation of the hydrazine complex 5 led to the dinuclear diazene complex [mu-N2H2{Ru(PPh3)(('bu)S4'] (6), which was characterized by an X-ray structure analysis. Crystals of 6.4CH2Cl2 are monoclinic, space group C2/c, with a = 2870.0(16) pm, b = 1380.4(4) pm, c - 2849.2(13) pm, beta - 93.65(4)-degrees, V = 11 265(9) X 10(6) pM3, Z = 4, and R (R(w)) = 0.075 (0.072) for 5801 reflections. The diazene (HN=NH) ligand of 6 is stabilized by intramolecular N-H...(S)2 hydrogen bonds, steric protection, and a Ru-N-N-Ru 4c-6e-pi bond, but according to NMR experiments, 6 is still highly reactive in solution. 4-6 can be regarded as model compounds for the active centers of nitrogenases, because they contain intermediates of N2 fixation bound to transition metal centers in a coordination sphere dominated by sulfur donors.