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Reactivity of [(μ-H)2Os3(CO)10] with Aminotributylstannane and Aminotrimethylstannane Derivatives

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journal contribution
posted on 02.08.2004, 00:00 by José Luis Gárate-Morales, Juan M. Fernández-G
The reaction of aminotributylstannane or aminotrimethylstannane derivatives with the dihydride of decacarbonyltriosmium in ether−hexane solution (5:1) at room temperature affords the heterometallic clusters [(μ-H)Os3(CO)10(HE)(SnR3)] (18) (HE = dimethylamine (1, 5), pyrrolidine (2, 6), piperidine (3, 7), and morpholine (4, 8)) and the α-carbon−hydrogen bond activation of the secondary amine moiety of (2) (2a) in low yield. In all these heterometallic clusters the secondary amine ligand occupies a weak axial coordination site on the osmium triangle, eventually stabilized through the formation of intramolecular hydrogen-bonding interaction between the N−H and the axial carbonyl ligands. The stannyl ligand (SnBu3 or SnMe3) occupies an equatorial position on the osmium triangle, as expected for a bulky substituent. The metal carbonyl angles open out and the Os−C−O axes deviate from linearity so as to bring the carbonyl moieties closer to the tin atom in an “umbrella effect”, for 3, 5, 6, 7, 7‘, 8, and 2a. We were unable to grow single crystals for the compounds 1, 2, and 4. However, the spectroscopic information (1H, 13C, and 119Sn NMR) is similar for compounds 18 and 2a. Thus, it is assumed that they should present similar interactions in the triosmium cluster. All the compounds were characterized by IR, 1H, 13C, and 119Sn NMR, mass spectra, and elemental analysis. Solid-state structures of 3, 5, 6, 7, 7‘, 8, and 2a were established by single-crystal X-ray diffraction analyses.