Activation of C–O and C–C Bonds and Formation of Novel HAlOH-Ether Complexes: An EPR Study of the Reaction of Ground-State Al Atoms with Methylethyl Ether and Diethyl Ether

Abstract

Reaction mixtures, containing Al atoms and methylethyl ether (MEE) or diethyl ether (DEE) in an adamantane matrix, were prepared with the aid of a metal-atom reactor known as a rotating cryostat. The EPR spectra of the resulting products were recorded from 77-260 K, at 10 K intervals. Al atoms were found to insert into methyl-O, ethyl-O, and C-C bonds to form CH(3)AlOCH(2)CH(3), CH(3)OAlCH(2)CH(3), and CH(3)OCH(2)AlCH(3), respectively, in the case of MEE while DEE produced CH(3)CH(2)AlOCH(2)CH(3) and CH(3)AlCH(2)OCH(2)CH(3), respectively. From the intensity of the transition lines attributed to the Al atom C-O insertion products of MEE, insertion into the methyl-O bond is preferred. The Al hyperfine interaction (hfi) extracted from the EPR spectra of the C-O insertion products was greater than that of the C-C insertion products, that is, 5.4% greater for the DEE system and 7% greater for the MEE system. The increase in Al hfi is thought to arise from the increased electron-withdrawing ability of the substituents bonded to Al. Besides HAlOH, resulting from the reaction of Al atoms with adventitious water, novel mixed HAlOH:MEE and HAlOH:DEE complexes were identified with the aid of isotopic studies involving H(2)(17)O and D(2)O. The Al and H hfi of HAlOH were found to decrease upon complex formation. These findings are consistent with the nuclear hfi calculated using a density functional theory (DFT) method with close agreement between theory and experiment occurring at the B3LYP level using a 6-311+G(2df,p) basis set.

Hydrogen migration dynamics in hydrated Al clusters: The Al17(−)·H2O system as an example

“…Al atoms have been found to react with individual water molecules [1][2][3][4][5][6][7][8][9][10] and also in conditions of microhydration. [11][12][13] Relay (Grotthuss-type) mechanisms and tunneling play a role in those reactions, which are of technological and astrophysical importance; Al oxide and hydroxide have recently been detected in the space.…”

Aluminum Atom Activation of C–S Bonds: An EPR Study of the Intermediates Formed in the Reaction Between Aluminum Atoms and Dialkyl Sulfides

“… a In MHz. b Reference . c Reference . d Reference . e This work. f See discussion section for analysis of magnetic parameters. …”

“…e Energy in hartrees. The magnetic parameters of CH 3 SAlCH 3 (DMS-1) and DMS-2 can be compared to those reported for the Al atom C− O insertion products of dimethyl 7,8 and methylethyl 34 ether, CH 3 AlOCH 3 , CH 3 AlOCH 2 CH 3 , and CH 3 OAlCH 2 CH 3 , respectively, Table 6. The values for the isotropic Al and 13 C hfi (where applicable) for these species are in line with those reported for CH 3 AlOCH 3 , CH 3 AlOCH 2 CH 3 , and CH 3 OAlCH 2 CH 3 with ρ 3s (Al) ranging from 0.22 to 0.27 and ρ 2s (C) ≈ 0.03−0.04.…”