文摘
The hexahydride complex OsH6(PiPr3)2 (1) reacts with 8-methylquinoline and 2-(dimethylamino)pyridineto give OsH3(CH2C9H6N)(PiPr3)2 (2) and OsH3{CH2N(CH3)-o-C5H4N}(PiPr3)2 (3), respectively, as a resultof the release of two hydrogen molecules of 1 and the C(sp3)-H bond activation of a methyl group ofthe organic substrates. In solution the hydride ligands and the hydrogen atoms of the methylene groupof 2 exchange their positions. The activation parameters for the process are H = 18.9 ± 0.1 kcal·mol-1and S = 3 ± 2 eu. Treatment of 2 with HBF4 affords the hydride-elongated dihydrogen derivative[OsH(2-H2)(CH3C9H6N)(PiPr3)2]BF4 (6), with the methyl group of the quinoline ligand coordinated ina 3-H2C fashion. The X-ray structure of 6 and the DFT optimization of the structure of the model cation[OsH(2-H2)(CH4)(NH3)(PMe3)2]+ prove that the methyl coordination in the agostic complex is similarto the methane coordination in the model compound. The reaction of 3 with HBF4 leads to the cycliccarbene derivative [OsH3{=CHN(CH3)-o-C5H4N}(PiPr3)2]BF4 (7), as a result of the release of a hydrogenmolecule and a C(sp3)-H bond activation on the methylene group of 3. The formation of 2, 3, 6, and 7has been analyzed by DFT calculations.
