Studies of cyclization reactions of linear cumulenes and heterocumulenes using the neutralization–reionization procedure and/or ab initio calculations
✍ Scribed by Tianfang Wang; John H. Bowie
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 421 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0277-7037
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✦ Synopsis
Abstract
A number of linear cumulenes and heterocumulenes have been made by charge stripping of anions of known bond connectivity in the source of a mass spectrometer. Some of these reactive molecules have been identified in interstellar molecular clouds. The structures of these neutrals may be investigated by reionization to a decomposing positive ion [the neutralization–reionization technique (^−^NR^+^)], and/or by ab initio calculations. Energized linear cumulenes and heterocumulenes may undergo cyclization to form stable cyclic isomers. To cite a selection of the examples described in this review: (i) four‐atom systems CCCC and some heterocumulenes CCCX (X = B, N, Al, Si, P) involve the formation of stable four‐membered ring rhombic (also called kite and fan) structures. One of the cyclic molecules, cyclo‐C~3~Si, has been detected in interstellar molecular clouds, (ii) five‐atom cumulene and heterocumulene systems are more complex. Linear CCCCC rearranges the carbon skeleton by forming a C substituted rhomboid system, CCCCO forms a three‐membered cyclic isomer, while nitrogen containing five‐atom cumulenes effect nitrile to isonitrile interconversion via three‐centered cyclized intermediates, and (iii) CCCCCC and CCCCBO cyclize to give unique six‐membered ring systems. © 2010 Wiley Periodicals, Inc., Mass Spec Rev 30:1225–1241, 2011