856438-74-9Relevant academic research and scientific papers
Sequential protonation and methylation of a hydride-osmium complex containing a cyclopentadienyl ligand with a pendant amine group
Esteruelas, Miguel A.,Lopez, Ana M.,Onate, Enrique,Royo, Eva
, p. 4094 - 4103 (2005)
Complex OsH{η5-C5H4(CH 2)2NMe2}(PiPr3) 2 (1) reacts with 1 equiv of trifluoromethanesulfonic acid (HOTf) and trifluoromethanesulfonic acid-d1 (DOTf) to produce the dihydride and hydride-deuteride complexes, [OsHE{η5-C5H 4(CH2)2NMe2}(PiPr 3)2]OTf (E = H (2), D (2-d1)), respectively. Treatment of 2 and 2-d1 with a second equivalent of HOTf gives [OsHE[η5-C5H4(CH2) 2NHMe2}(PiPr3)2][OTf] 2 (E = H (3), D (3-d1)) as a result of the protonation of the nitrogen atom. While the hydride and deutende ligands of 2, 2-d1, 3, and 3-d1 do not undergo any H/D exchange process with the solvent, in acetone-d6 the NH proton of 3 and 3-d1 changes places with a deuterium atom of the solvent to yield [OsHE{η5- C5H4(CH2)2NDMe2}(P iPr3)2][OTf]2 (E = H (3-Nd 1), D (3-d2)). Complex 3-Nd1 can also be obtained from the treatment of complex 2 with DOTf in dichloromethane. No exchange process between the hydride and the ND positions in 3-Nd1 or between the deuteride and NH positions in 3-d1 has been observed. Treatment of 3-Nd1 and 3-d1 with sodium methoxide results in a selective reaction of the base with the ammonium group to regenerate 2 and 2-d1, respectively. Complex 1 also reacts with methyl and methyl-d3 trifluoromethanesulfonate (CH3OTf and CD 3OTf, respectively) to give [OsH{η5-C 5H4(CH2)2NMe2CE 3}(PiPr3)2]OTf (E = H (4), D (4-d3)) as a result of the addition of the CE3 (E = H, D) group to the nitrogen atom. Complex 4 has been characterized by an X-ray diffraction analysis. It reacts with a second molecule of CH3OTf or CD3OTf to produce [OsH{η5-C5H 4(CH2)2-NMe3}{CH 2CH(CH3)PiPr2}(PiPr 3)][OTf]2 (5). Similarly, complex 4-d3 reacts with a second molecule of CH3OTf or CD3OTf to yield [OsH{η5-C5H4(CH2) 2NMe2CD3}{CH2CH(CH 3)PiPr2}(PiPr3)][OTf] 2 (5-d3). In acetonitrile, complex 5 evolves to an equilibrium mixture of the acetonitrile adducts [Os{η5-C 5H4(CH2)2NMe3}(NCCH 3)(PiPr3)2][OTf]2 (7) and [Os{η5-C5H4(CH2) 2NMe3}(NCCH3)2(PiPr 3)][OTf]2 (8). In methanol or methanol-d4, complex 4 is not stable and loses trimethylamine to give the vinylcyclopentadienyl derivatives [OsHE(η5-C5H 4CH=CH2)(PiPr3)2]OTf (E = H (9), D (9-d1)) as a result of the protonation or deuteration of the metallic center and a subsequent Hofmann elimination. Protonation of 4 with HOTf gives the dihydride-trimethylammonium derivative [OsH2{η 5-C5H4(CH2)2NMe 3}(PiPr3)2]-[OTf]2 (10). Treatment of 9 with sodium methoxide produces OsH(η5-C 5H4CH=CH2)(PiPr3) 2 (11).
