Phosphane effects on formation and reactivity of [Ru(L)(PR3)(`N2Me2S2')] complexes with L=N2, N2H4, NH3, and CO |
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Authors: | D Sellmann A Rösler FW Heinemann M Moll |
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Institution: | Institute of Inorganic Chemistry II, University of Erlangen-Nuremberg, Egerlandstrasse 1, D-91058 Erlangen, Germany |
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Abstract: | Metal-sulfur complex fragments, to which small molecules like N2, N2H2, N2H4, NH3, or CO can bind, are desirable model compounds concerning enzymatic N2 fixation.This paper reports on the effects of the phosphane co-ligand on formation and reactivity of Ru(L)(PR3)(`N2Me2S2')] `N2Me2S2'2−=1,2-ethanediamine-N,N′-dimethyl-N,N′-bis(2-benzenethiolate)(2−)] complexes with nitrogenase relevant ligands, especially N2, N2H4, NH3, and CO.Treatment of Ru(NCCH3)4Cl2] with Li2`N2Me2S2', excessive LiOMe, bulky PPh3 or PCy3, respectively, led to the formation of two series of Ru(L)(PR3)(`N2Me2S2')] complexes for R=Ph: 1b, 1c (L=NCCH3), 6b (L=N2H4), 7b (L=N2), 8b1-3 (L=CO), 9b (L=NH3); for R=Cy: 1a (L=NCCH3), 6a (L=N2H4), 7a (L=N2), 8a (L=CO), 9a (L=NH3)]. While the use of PPh3 (θ=145°) yielded cis,trans and cis,cis isomers of Ru(NCCH3)(PPh3)(`N2Me2S2')] (1b, 1c), no isomer formation was observed with the bulkier phosphane PCy3 (θ=170°). Sterically less demanding phosphanes (θ=118-132°) afforded bisphosphane complexes Ru(PR3)2(`N2Me2S2')] 2d (R=Me), 2e (R=Et), 2f (R=nPr), and 2g (R=nBu)], which were practically inert and could only be converted in two cases and under drastic reaction conditions into the CO complexes Ru(CO)(PR3)(`N2Me2S2')] 4e (R=Et), 4f (R=nPr)]. The chelating bidentate phosphane dppe (bisdiphenylphosphanoethane) yielded exclusively the mononuclear complex Ru(dppe)(`N2Me2S2')] (3). |
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Keywords: | Enzyme models Ligand effects Nitrogenases Phosphanes S ligands |
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