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Gas-phase reactions of the group 10 organometallic cations, [(phen)M(CH3)](+) with acetone: only platinum promotes a catalytic cycle via the enolate [(phen)Pt(OC(CH2)CH3)](+)

Citation

Greis, K and Canty, AJ and O'Hair, RAJ, Gas-phase reactions of the group 10 organometallic cations, [(phen)M(CH3)](+) with acetone: only platinum promotes a catalytic cycle via the enolate [(phen)Pt(OC(CH2)CH3)](+), Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics, 233, (6) pp. 845-864. ISSN 0942-9352 (2019) [Refereed Article]

Copyright Statement

2019 Walter de Gruyter GmbH, Berlin/Boston.

DOI: doi:10.1515/zpch-2018-1355

Abstract

Electrospray ionisation of the ligated group 10 metal complexes [(phen)M(O2CCH3)2] (M = Ni, Pd, Pt) generates the cations [(phen)M(O2CCH3)]+, whose gas-phase chemistry was studied using multistage mass spectrometry experiments in an ion trap mass spectrometer with the combination of collision-induced dissociation (CID) and ion-molecule reactions (IMR). A new catalytic cycle has been discovered. In step 1, decarboxylation of [(phen)M(O2CCH3)]+ under CID conditions generates the organometallic cations [(phen)M(CH3)]+, which react with acetone to generate the [(phen)M(CH3)(OC(CH3)2)]+ adducts in competition with formation of the coordinated enolate for M = Pt (step 2). For M = Ni and Pd, the adducts regenerate [(phen)M(CH3)]+ upon CID. In the case of M = Pt, loss of methane is favored over loss of acetone and results in the formation of the enolate complex, [(phen)Pt(OC(CH2)CH3)]+. Upon further CID, both methane and CO loss can be observed resulting in the formation of the ketenyl and ethyl complexes [(phen)Pt(OCCH)]+ and [(phen)Pt(CH2CH3)]+ (step 3), respectively. In step 4, CID of [(phen)Pt(CH2CH3)]+ results in a beta-hydride elimination reaction to yield the hydride complex, [(phen)Pt(H)]+, which reacts with acetic acid to regenerate the acetate complex [(phen)Pt(O2CCH3)]+ and H2 in step 5. Thus, the catalytic cycle is formally closed, which corresponds to the decomposition of acetone and acetic acid into methane, CO, CO2, ethene and H2. All except the last step of the catalytic cycle are modelled using DFT calculations with optimizations of structures at the M06/SDD 6-31G(d) level of theory.

Item Details

Item Type:Refereed Article
Keywords:organopalladium, platinum, and nickel chemistry related to catalysis, DFT, mass spectrometry
Research Division:Chemical Sciences
Research Group:Inorganic Chemistry
Research Field:Transition Metal Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
UTAS Author:Canty, AJ (Professor Allan Canty)
ID Code:134555
Year Published:2019
Web of Science® Times Cited:2
Deposited By:Chemistry
Deposited On:2019-08-19
Last Modified:2019-12-10
Downloads:0

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