Synthesis, Reactivity, and Characterization of the First Donor-Stabilized Silylene Complexes of Osmium meso-Tetra-p-tolylporphyrin (TTP)Os=SiR2, THF (R = Me, Et, iPr) and the Molecular Structure of (TTP)Os=SiEt2, 2THF

L. Keith Woo, Daniel A. Smith, Victor G. Young

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Abstract

The preparation and characterization of the first donor-stabilized silylene complexes of osmium meso-tetra-p-tolylporphyrin are described. The silylene complex (TTP)Os==SiMe2-THF (1-THF) is prepared by the reaction of [Os(TTP)]2 with hexamethylsilacyclopropane. Treating K2[Os(TTP)] with Cl2SiItj also generates the silylene complexes (TTP)Os=SiR2-THF [R = Me (1-THF), Et (2-THF), Pr (3-THF)]. XH NMR spectroscopy indicates that, in solution, one molecule of THF is coordinated to the silicon in all of these complexes. This has been verified by 2D-NOESY experiments. In 2-THF, the methylene protons are diastereotopic, indicating that the silicon is pyramidalized. Addition of 1 equiv of pyridine to 1-THF or 2-THF replaces the THF on silicon with pyridine. Coordination of pyridine to silicon was also confirmed by a 2D-NOESY experiment. The structure of 2-THF was determined by a single-crystal X-ray diffraction experiment. The diethyl complex 2–2THF crystallizes with two additional THF molecules as solvates in the monoclinic space group P2t/c with a = 21.649 (5) A, b - 13.829 (3) A, c = 19.526 (3) A, j3 = 98.08 (2)°, V = 5788 (4) A3, Z = 4, R = 5.0%, and Rw = 5.7 %. The Os-Si distance (2.325 (8) A) is the shortest observed to date. Other metrical parameters of this complex are discussed.

Original languageEnglish (US)
Pages (from-to)3977-3982
Number of pages6
JournalOrganometallics
Volume10
Issue number12
DOIs
StatePublished - Dec 1 1991

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