title: Ammonia Borane Dehydrogenation Catalyzed by (κ4-EP3)Co(H) [EP3= E(CH2CH2PPh2)3; E = N, P] and H2Evolution from Their Interaction with NH Acids.
abstract: Two Co(I) hydrides containing the tripodal polyphosphine ligand EP3, (κ4-EP3)Co(H) [E(CH2CH2PPh2)3; E = N (1), P (2)], have been exploited as ammonia borane (NH3BH3, AB) dehydrogenation catalysts in THF solution at T = 55 °C. The reaction has been analyzed experimentally through multinuclear (11B,31P{1H},1H) NMR and IR spectroscopy, kinetic rate measurements, and kinetic isotope effect (KIE) determination with deuterated AB isotopologues. Both complexes are active in AB dehydrogenation, albeit with different rates and efficiency. While 1 releases 2 equiv of H2per equivalent of AB in ca. 48 h, with concomitant borazine formation as the final "spent fuel", 2 produces 1 equiv of H2only per equivalent of AB in the same reaction time, along with long-chain poly(aminoboranes) as insoluble byproducts. A DFT modeling of the first AB dehydrogenation step has been performed, at the M06//6-311++G** level of theory. The combination of the kinetic and computational data reveals that a simultaneous B-H/N-H activation occurs in the presence of 1, after a preliminary AB coordination to the metal center. In 2, no substrate coordination takes place, and the process is better defined as a sequential BH3/NH3insertion process on the initially formed [Co]-NH2BH3amidoborane complex. Finally, the reaction of 1 and 2 with NH-acids [AB and Me2NHBH3(DMAB)] has been followed via VT-FTIR spectroscopy (in the -80 to +50 °C temperature range), with the aim of gaining a deeper experimental understanding of the dihydrogen bonding interactions that are at the origin of the observed H2evolution.
authors.affiliation: Istituto di Chimica dei Composti Organometallici-Consiglio Nazionale delle Ricerche (ICCOM - CNR) , Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Todisco
authors.affiliation: Istituto di Chimica dei Composti Organometallici-Consiglio Nazionale delle Ricerche (ICCOM - CNR) , Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.
authors.forename: Lapo
authors.initials: L
authors.lastname: Luconi
authors.affiliation: Istituto di Chimica dei Composti Organometallici-Consiglio Nazionale delle Ricerche (ICCOM - CNR) , Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.|Kazan Federal University , Kremlyovskaya Street 18, 420008 Kazan, Russia.
authors.forename: Giuliano
authors.identifier: http://orcid.org/0000-0002-0315-3286
authors.initials: G
authors.lastname: Giambastiani
authors.affiliation: Istituto di Chimica dei Composti Organometallici-Consiglio Nazionale delle Ricerche (ICCOM - CNR) , Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.
authors.forename: Andrea
authors.identifier: http://orcid.org/0000-0002-1283-2803
authors.initials: A
authors.lastname: Rossin
authors.affiliation: Istituto di Chimica dei Composti Organometallici-Consiglio Nazionale delle Ricerche (ICCOM - CNR) , Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Peruzzini
authors.affiliation: A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS) , Vavilova Street 28, 119991 Moscow, Russia.|People's Friendship University of Russia (RUDN University), 6 Miklukho-Maklay St., 117198 Moscow, Russia.
authors.forename: Igor E
authors.identifier: http://orcid.org/0000-0003-4142-454X
authors.initials: IE
authors.lastname: Golub
authors.affiliation: A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS) , Vavilova Street 28, 119991 Moscow, Russia.
authors.forename: Oleg A
authors.identifier: http://orcid.org/0000-0002-7963-2806
authors.initials: OA
authors.lastname: Filippov
authors.affiliation: A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS) , Vavilova Street 28, 119991 Moscow, Russia.
authors.forename: Natalia V
authors.identifier: http://orcid.org/0000-0001-9346-8208
authors.initials: NV
authors.lastname: Belkova
authors.affiliation: A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS) , Vavilova Street 28, 119991 Moscow, Russia.
authors.forename: Elena S
authors.initials: ES
authors.lastname: Shubina