Activation of C-H Bonds in Thiophenes by Rh(PMe3)2(CO)Cl: A Low-Temperature NMR Study
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- 作者：Martin G. Partridge ; Leslie D. Field ; and Barbara A. Messerle
- 刊名：Organometallics
- 出版年：1996
- 出版时间：January 23, 1996
- 年：1996
- 卷：15
- 期：2
- 页码：872 - 877
- 全文大小：148K
- 年卷期：v.15,no.2(January 23, 1996)
- ISSN：1520-6041
文摘
Irradiation oftrans-Rh(PMe3)2(CO)Cl(1) at 230 K in the presence of2,5-dimethylthiopheneor thiophene affords products arising from C-H insertion.Irradiation of 1 in 2,5-dimethylthiophene affords three products: two conformers of thesix-coordinate complextrans-Rh(PMe3)2(CO)(Cl)(2,5-dimethyl-3-thienyl)H,related by rotation about the Rh-C bond,andtrans-Rh(PMe3)2(CO)(2,5-dimethyl-3-thienyl).The major conformer oftrans-Rh(PMe3)2(CO)(Cl)(2,5-dimethyl-3-thienyl)H decays back to 1at a rate of (2.9 ± 0.2) × 10-4s-1 at 273K, whereas the minor conformer andtrans-Rh(PMe3)2(CO)(2,5-dimethyl-3-thienyl)arerelatively stable. Irradiation of (1) in thepresence of thiophene affords products arisingfrom addition at both the 2- and 3-positions in the thiophene ring:trans-Rh(PMe3)2(CO)(Cl)(2-thienyl)H,Rh(PMe3)2(CO)(Cl)(3-thienyl)Handtrans-Rh(PMe3)2(CO)(2-thienyl).Thesix-coordinate Rh(III) species each exist as two rotamers at 230 Krelated by rotation aboutthe Rh-Caryl bond. Irradiation of 1 inthiophene or 2,5-dimethylthiophene under nitrogenwith UV light at low temperatures also gives rise to products arisingfrom thiophenecarbonylation.