The preparation and characterization of the first donor-stabilized silylene complexes of osmium meso-tetra-p-tolylporphyrin are described. The silylene complex (TTP)Os=SiM~·THF (l·THF) is prepared by the reaction of [Os(TTP)b with hexamethylsilacyclopropane. Treating K2[0s(TTP)] with Cl2Si~ also generates the silylene complexes (TTP)Os=SiR2·THF [R =Me (l·THF), Et (2·THF), ipr (3·THF)]. 1H 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 l·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 P2d c with a = 21.649 (5) A, b = 13.829 (3) A, c = 19.526 (3) A, 13 = 98.08 (2) 0 , 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.
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