Reactivity of a Thiolate‐Bridged Dinuclear Ruthenium Complex with Nitrogenous Molecules: Spectroscopic Identification of a Labile Dinitrogen Complex

Abstract
Reactions of the thiolate‐bridged diruthenium complex [Ru(pybuS4)]2 (1) {pybuS42− = 2,6‐bis[(3,5‐di‐tert‐butyl‐2‐sulfanylphenyl)thiomethyl]pyridine(2−)} with small‐molecule ligands L afforded the corresponding mononuclear complexes [Ru(L)(pybuS4)] [L = H (2); CH3CN (3); NH3 (4); CO (5); N2H4 (6); PMe3 (7); N3 (8)]. The molecular structures of 3, 4, and 5 exhibit pseudooctahedral geometry with two thiolate and two thioether donor atoms in a trans configuration. Complexes 2−8 exhibit a quasi‐reversible, one‐electron redox wave of the RuII/RuIII couple in the region between E1/2 = +0.214 and +0.460 V vs. NHE. Complex 1 reacts reversibly with N2 (60 bar) at 40 °C to give the labile dinitrogen complex [Ru(N2)(pybuS4)] (9). Complex 9 can also be obtained from the reaction between 3 and N2 (20 bar) at room temperature. Treatment of 4 with NO afforded the labile 19‐valence‐electron species [Ru(NO)(pybuS4)] (10) in solution, which could subsequently be converted to 9 upon highpressure reaction with N2 (20 bar). In contrast, the analogous reaction of 4 with NOBF4 results in the formation of the oxidized complex [Ru(NH3)(pybuS4)]BF4 (11), the structure of which was confirmed by X‐ray structure analysis. The carbonyl complex [Ru(CO)(pybuS4)] (5) could be reversibly protonated at the thiolate sulfur atom to give [Ru(CO)(pybuS4H)]BF4 (12). UV irradiation of 5 and 12 under N2 at −80 °C produced the short‐lived species 9 and 13, respectively, which were identified spectroscopically. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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