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Issue 21, 2003
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Redistribution at silicon by ruthenium complexes. Bonding mode of the bridging silanes in Ru2H4(μ-η2222-SiH4)(PCy3)4 and Ru2H2(μ-η22-H2Si(OMe)2)3(PCy3)2

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Abstract

The bis(dihydrogen) complex RuH22-H2)2(PCy3)2 (1) reacts with 2 equiv. of H2SiMePh to produce a mixture of Ru2H4(μ-η2222-SiH4)(PCy3)4 (2) and RuH22-H2)(η2-HSiPh3)(PCy3)2 (4) together with HSiMePh2, HSiMe2Ph and traces of HMe2SiSiMe2H as a result of redistribution at silicon. The bridging SiH4 ligand in 2 is coordinated to the two ruthenium via four σ-Si–H bonds in agreement with NMR, X-ray data (on 2, and 2′ the analogous PiPr3 complex) and DFT calculations. Each interaction involves σ-donation to a ruthenium and back-bonding from the other ruthenium. Elimination of SiH4 and formation of RuH2(CO)2(PCy3)2 (5), RuH2(tBuNC)2(PCy3)2 (6) or RuH(η2-H2)Cl(PCy3)2 (7) were observed upon the reaction of 2 with CO, tBuNC, CH2Cl2, respectively. No reaction occurred in the presence of H2, but H/D exchange was observed under D2 atmosphere. Another redistribution reaction at silicon can be obtained by adding 4 equiv. of HSi(OMe)3 to 2 to produce Si(OMe)4 and Ru2H2(μ-η22-H2Si(OMe)2)3(PCy3)2 (3) displaying three bridging (μ-η22 alkoxysilane) ligands. Complex 3 is characterized by multinuclear NMR spectroscopies and by a crystal structure. DFT calculations show that the model complex Ru2H2(μ-η22-H2Si(OR)2)3(PR3)2 (R = H, Me) is a minimum on the potential energy surface, and support the dihydride formulation with three bridging H2Si(OMe)2 ligands coordinated to the two ruthenium through σ-Si–H bonds.

Graphical abstract: Redistribution at silicon by ruthenium complexes. Bonding mode of the bridging silanes in Ru2H4(μ-η2:η2:η2:η2-SiH4)(PCy3)4 and Ru2H2(μ-η2:η2-H2Si(OMe)2)3(PCy3)2

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Publication details

The article was received on 14 Apr 2003, accepted on 15 Jul 2003 and first published on 22 Sep 2003


Article type: Paper
DOI: 10.1039/B304122K
Citation: Dalton Trans., 2003,0, 4139-4146
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    Redistribution at silicon by ruthenium complexes. Bonding mode of the bridging silanes in Ru2H4(μ-η2222-SiH4)(PCy3)4 and Ru2H2(μ-η22-H2Si(OMe)2)3(PCy3)2

    R. B. Said, K. Hussein, J. Barthelat, I. Atheaux, S. Sabo-Etienne, M. Grellier, B. Donnadieu and B. Chaudret, Dalton Trans., 2003, 0, 4139
    DOI: 10.1039/B304122K

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