Reaction pathways of Rh+ (3F and 1D) with CH3OCH3 in the gas phase.
BACKGROUND
The mass spectrometric studies of transition metal ion-ether reactions are informative in elucidating the principles of metal ion mediated demethanation and dehydrogenation. In order to obtain a deeper understanding of the role of metal ions, it is essential to explore the detailed reaction mechanisms of these reactions, here studied using Rh(+) and dimethyl ether as a model system.


METHODS
The gas-phase demethanation and dehydrogenation pathways of dimethyl ether mediated by Rh(+) ((3)F and (1)D) were investigated by density functional theory in conjunction with the Stuttgart RSC + 6-311 + G(d) basis set. Both singlet and triplet states of reactivity were explored.


RESULTS
The results indicate that both C-O and C-H bond activation of dimethyl ether mediated by Rh(+) could induce the demethanation reaction. The triplet state demethanation reaction prefers to proceed through C-O bond activation, while the singlet state demethanation channel via C-H bond activation is energetically more favorable. The singlet state dehydrogenation of the ionic product (formaldehyde/Rh(+)) occurs by decomposition of rhodium carbonyl dihydride, while the triplet state dehydrogenation is induced by dissociation of the carbonyl(η(2)-dihydrogen) rhodium species.


CONCLUSIONS
Based on the results, it is believed that the demethanation reaction of dimethyl ether mediated by transition metal monocation would preferably occur through the C-O bond activation pathway. Combined with previous studies, a general reaction mechanism of the transition metal monocation with dimethyl ether is proposed.
Key Laboratory for Applied Technology of Sophisticated Analytical Instruments, Academy of Sciences, Shandong, Jinan, PR China. xiangfchen@yahoo.com.cn
Xiangfeng
X
Chen
Hoi-sze
HS
Yeung
Ning
N
Ding
D005557:Formaldehyde; D005740:Gases / Q000737:chemistry*; D013058:Mass Spectrometry; D008738:Methyl Ethers / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D012238:Rhodium / Q000737:chemistry*
D005740:Gases; D008738:Methyl Ethers; D005557:Formaldehyde; C033413:dimethyl ether; D012238:Rhodium