Transition Metal Complexes with Sulfur Ligands, 143 Coordination of CO, NO, N_2H_2, and Other Nitrogenase Relevant Small Molecules to Sulfur-Rich Ruthenium Complexes with the New Ligand 'tpS_4'~(2-) = 1,2-Bis(2-mercaptophenylthio) phenylene(2-)

摘要

In the search for ruthenium complexes with sulfur-dominated coordination spheres that bind, activate, or stabilize nitrogenase relevant molecules, complexes containing the new and robust tetradentate ligand 'tpS_4'-H_2 were synthesized. Treatment of [RuCl_2(pph_3)_3] with 'tpS_4'`(2-) gives [Ru(PPh_3)_2('tpS_4')] (1), which contains two labile PPm_3 ligands. The reaction of 1 with PEt_3 or DMSO led to substitution of both PPh_3 ligands, yielding [Ru(PEt_3)_2('tpS_4')] (2) and [Ru(DMSO)_2('tpS_4')] (3), respectively. When treated with nitrogenous ligands, complex 1 lost only one PPh_3 ligand to yield [Ru(L)(PPh_3)('tpS_4')] complexes where L = py (7), NH_3 (8), N_2H_4 (9), NH_2NHMe (10), and CH_3CN (12), all of which are labile. The labile acetonitrile complex [Ru(CH_3CN)(PPh_3)('tpS_4')] (12) proved to be particularly suited as a precursor for the syntheses of other [Ru(L)(PPh_3)('tpS_4')] complexes. The 18 and 19 valence electron NO complexes [Ru(NO)(PPh_3)('tpS_4')]BF_4 (13) and [Ru(NO)(PPh_3)('tpS_4')] (14), (NEt_4)[Ru(N_3)(PPh_3)('tpS_4')] (15), [Ru(I)(PPh_3)('tpS_4')] (16), and [Ru(N_3)(PPh_3)('tpS_4')] (17) were obtained starting from complex 12. The labile mononuclear hydrazine complex [Ru(N_2H_4)(PPh_3)('tpS_4')] (9) gave the dinuclear complex [μ-N_2H_4{Ru(PPh_3)('tpS_4')}_2] (18) by dissociation of hydrazine. The dinuclear diazene complex [μ-N_2H_2{Ru(PPh_3)('tpS_4')}_2] (19) was obtained by oxidation of 9 and more readily from [Ru(CH_3CN)(PPh_3)('tpS_4')] (12) and N_2H_2, which was generated in situ from K_2N_2(CO_2)_2 and acetic acid. The molecular structures of 7, 13, 16, 18, and 19 were determined by X-ray structure analyses. The complexes 18 and 19 represent the first complexes containing the hydrazine/diazene couple, which enables us to compare both the bonding features and the formation of N-H…S bridges when hydrazine and diazene bind to transition metal sulfur sites.