C–H bond activation of benzene and thiophene by photochemically generated rhenocene cation
A cationic rhenocene-acetonitrile adduct [Cp2Re(NCMe)](BF4)(1) reacted with an excess of benzene, thiophene, 2-methylthiophene, and pyrrole under UV irradiation to afford the C–H bond activation products [Cp2Re(H)R]BF4 (R = phenyl, 2-thienyl, 2-(5-methylthienyl), 2-pyrrolyl) in high yields. In cases...
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| Format: | Article |
| Language: | English |
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Wiley
1999-01-01
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| Series: | International Journal of Photoenergy |
| Online Access: | http://dx.doi.org/10.1155/S1110662X99000276 |
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| author | Hiroshi Ogino Hiromi Tobita Kouji Endo Kiyonari Hashidzume |
| author_facet | Hiroshi Ogino Hiromi Tobita Kouji Endo Kiyonari Hashidzume |
| author_sort | Hiroshi Ogino |
| collection | DOAJ |
| description | A cationic rhenocene-acetonitrile adduct [Cp2Re(NCMe)](BF4)(1) reacted with an excess of benzene,
thiophene, 2-methylthiophene, and pyrrole under UV irradiation to afford the C–H bond activation
products [Cp2Re(H)R]BF4 (R = phenyl, 2-thienyl, 2-(5-methylthienyl), 2-pyrrolyl) in high yields. In cases
of thiophene derivatives and pyrrole, α-C–H bonds are selectively activated. A plausible mechanism involves
the photodissociation of acetonitrile from 1 to generate a coordinatively unsaturated rhenocene cation
[Cp2Re]+. When 2,5-dimethylthiophene and dibenzothiophene, having no α-C–H bonds, were used as substrates,
products of the activation of other C–H bonds were formed first, but they isomerized to thermodynamically
more stable η11-S-coordinated complexes in refluxing acetone. On the other hand, irradiation
of the η1-S-coordinated complexes reproduced the original C–H bond activation products. Because of the
cationic character, [Cp2Re(H)R]BF4 were readily deprotonated by triethylamine to give neutral rhenocene
derivatives Cp2ReR. When R is thienyl or 2-(5-methylthienyl), treatment of Cp2ReR with HBF4⋅Et2O and MeI resulted in protonation and methylation to give [Cp2Re(H)R]BF4 (R = and [Cp2Re(Me)R]I. Thermolysis of
[Cp2Re(Me)R]I
in the presence of PPh3 unexpectedly resulted in migration of R to the Cp ring to give [(2 thienyl C5H4)CpRe(PPh3)]I. |
| format | Article |
| id | doaj-art-85198869a8ff462d8cdbdf32ac7c670c |
| institution | Kabale University |
| issn | 1110-662X |
| language | English |
| publishDate | 1999-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | International Journal of Photoenergy |
| spelling | doaj-art-85198869a8ff462d8cdbdf32ac7c670c2025-02-03T01:30:41ZengWileyInternational Journal of Photoenergy1110-662X1999-01-011315716010.1155/S1110662X99000276C–H bond activation of benzene and thiophene by photochemically generated rhenocene cationHiroshi Ogino0Hiromi Tobita1Kouji Endo2Kiyonari Hashidzume3Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, JapanDepartment of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, JapanDepartment of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, JapanDepartment of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, JapanA cationic rhenocene-acetonitrile adduct [Cp2Re(NCMe)](BF4)(1) reacted with an excess of benzene, thiophene, 2-methylthiophene, and pyrrole under UV irradiation to afford the C–H bond activation products [Cp2Re(H)R]BF4 (R = phenyl, 2-thienyl, 2-(5-methylthienyl), 2-pyrrolyl) in high yields. In cases of thiophene derivatives and pyrrole, α-C–H bonds are selectively activated. A plausible mechanism involves the photodissociation of acetonitrile from 1 to generate a coordinatively unsaturated rhenocene cation [Cp2Re]+. When 2,5-dimethylthiophene and dibenzothiophene, having no α-C–H bonds, were used as substrates, products of the activation of other C–H bonds were formed first, but they isomerized to thermodynamically more stable η11-S-coordinated complexes in refluxing acetone. On the other hand, irradiation of the η1-S-coordinated complexes reproduced the original C–H bond activation products. Because of the cationic character, [Cp2Re(H)R]BF4 were readily deprotonated by triethylamine to give neutral rhenocene derivatives Cp2ReR. When R is thienyl or 2-(5-methylthienyl), treatment of Cp2ReR with HBF4⋅Et2O and MeI resulted in protonation and methylation to give [Cp2Re(H)R]BF4 (R = and [Cp2Re(Me)R]I. Thermolysis of [Cp2Re(Me)R]I in the presence of PPh3 unexpectedly resulted in migration of R to the Cp ring to give [(2 thienyl C5H4)CpRe(PPh3)]I.http://dx.doi.org/10.1155/S1110662X99000276 |
| spellingShingle | Hiroshi Ogino Hiromi Tobita Kouji Endo Kiyonari Hashidzume C–H bond activation of benzene and thiophene by photochemically generated rhenocene cation International Journal of Photoenergy |
| title | C–H bond activation of benzene and thiophene by photochemically generated rhenocene cation |
| title_full | C–H bond activation of benzene and thiophene by photochemically generated rhenocene cation |
| title_fullStr | C–H bond activation of benzene and thiophene by photochemically generated rhenocene cation |
| title_full_unstemmed | C–H bond activation of benzene and thiophene by photochemically generated rhenocene cation |
| title_short | C–H bond activation of benzene and thiophene by photochemically generated rhenocene cation |
| title_sort | c h bond activation of benzene and thiophene by photochemically generated rhenocene cation |
| url | http://dx.doi.org/10.1155/S1110662X99000276 |
| work_keys_str_mv | AT hiroshiogino chbondactivationofbenzeneandthiophenebyphotochemicallygeneratedrhenocenecation AT hiromitobita chbondactivationofbenzeneandthiophenebyphotochemicallygeneratedrhenocenecation AT koujiendo chbondactivationofbenzeneandthiophenebyphotochemicallygeneratedrhenocenecation AT kiyonarihashidzume chbondactivationofbenzeneandthiophenebyphotochemicallygeneratedrhenocenecation |