title: Hydrazine N-N Bond Cleavage over Silica-Supported Tantalum-Hydrides.
abstract: Hydrazine reacts with silica-supported tantalum-hydrides [(≡SiO)2TaHx] (x = 1, 3), 1, under mild conditions (100 °C). The IR in situ monitoring of the reaction with N2H4 or (15)N2H4, and the solid-state MAS NMR spectra of the fully (15)N labeled compounds (CP (15)N, (1)H-(15)N HETCOR, (1)H-(1)H double-quantum, and (1)H-(1)H triple-quantum spectra) were used to identify stable intermediates and products. DFT calculations were used for determining the reaction pathway and calculating the (15)N and (1)H NMR chemical shifts. Combining the experimental and computational studies led to the following results. At room temperature, only hydrazine adducts, 1-N2H4, are formed. Upon heating at 100 °C, the hydrazine adducts are converted to several species among which [(≡SiO)2Ta(═NH)(NH2)], 2, [(≡SiO)2TaH(NH2)2], 3, and [(≡SiO)2TaH2(NH-NH2)], 4, were identified. The final product 2 is also formed in the reaction of N2 with the same silica-supported tantalum-hydride complexes, and the species identified as 3 and 4 had been previously suggested by DFT studies as intermediates on the reaction pathway for N-N cleavage in N2. The present computational studies (cluster models with M06 functional complemented by selected calculations with periodic calculations) show that 2 is formed via 3 and 4, with either N2 or N2H4. This strengthens the previous proposal of the existence of 3 and 4 as intermediates in the reaction of N2 with the tantalum-hydrides. However, the reaction of N2 does not imply the formation of N2H4 or its hydrazido monoanionic or dianionic ligand as an intermediate. For this reason, this study informs both on the similarities and differences of the reaction pathways involving N2 and N2H4 with tantalum-hydrides.
authors.affiliation: Laboratoire C2P2 (équipe COMS), UMR 5265 CNRS-Université de Lyon 1-CPE Lyon , 43, Bvd du 11 Novembre 1918, 69616 Villeurbanne, France.
authors.forename: Hong-Peng
authors.initials: HP
authors.lastname: Jia
authors.affiliation: Laboratoire C2P2 (équipe COMS), UMR 5265 CNRS-Université de Lyon 1-CPE Lyon , 43, Bvd du 11 Novembre 1918, 69616 Villeurbanne, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Gouré
authors.affiliation: Departament de Química, Universitat Autònoma de Barcelona , 08193 Bellaterra, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Solans-Monfort
authors.affiliation: Laboratoire C2P2 (équipe COMS), UMR 5265 CNRS-Université de Lyon 1-CPE Lyon , 43, Bvd du 11 Novembre 1918, 69616 Villeurbanne, France.
authors.forename: Jessica
authors.initials: J
authors.lastname: Llop Castelbou
authors.affiliation: Laboratoire C2P2 (équipe COMS), UMR 5265 CNRS-Université de Lyon 1-CPE Lyon , 43, Bvd du 11 Novembre 1918, 69616 Villeurbanne, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Chow
authors.affiliation: Laboratoire C2P2 (équipe COMS), UMR 5265 CNRS-Université de Lyon 1-CPE Lyon , 43, Bvd du 11 Novembre 1918, 69616 Villeurbanne, France.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Taoufik
authors.affiliation: Institut Charles Gerhardt, UMR 5253 CNRS Université de Montpellier , cc 1501, Place E. Bataillon, 34095 Montpellier, France.
authors.forename: Odile
authors.initials: O
authors.lastname: Eisenstein
authors.affiliation: Laboratoire C2P2 (équipe COMS), UMR 5265 CNRS-Université de Lyon 1-CPE Lyon , 43, Bvd du 11 Novembre 1918, 69616 Villeurbanne, France.
authors.forename: Elsje Alessandra
authors.initials: EA
authors.lastname: Quadrelli