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Nitrile ylides also known as ''nitrilium ylides'', or ''nitrilium methylides'' are generally reactive intermediates. With a few exceptions, they cannot be isolated. However, a structure has been determined on a (particularly stable nitrile ylide ) by X-ray crystallography. Another nitrile ylide has been captured under cryogenic conditions. As ylides, they possess a negative charge and a positive charge on adjacent atoms. As a 1,3-dipole, several resonance structures can be drawn (1a-d). The most appropriate resonance structure is dependent upon the substituent pattern (the identity of the R and R' groups in 1 and 2). The 3-dimensional structure of the nitrilium ylide itself may also provide a clue as to the most appropriate resonance structure, with a linear R-C≡N-C unit supportive of the charge distribution indicated for resonance structures 1a & 1b and also consistent with the nomenclature ''nitrilium ylide''. As resonance structures 1c & 1d become more important the nitrilium ylide distorts its geometry in favor of a different valence tautomer, 2. 1024px Nitrile ylides are isoelectronic with nitrile oxides. 124px == Generation == Nitrile ylides can be obtained by the addition of electrophilic carbenes to nitriles, by the photochemical ring opening of azirines or isoxazoles and by dehydrochlorination of imidoyl chlorides. The latter is the most reliable method. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Nitrile ylide」の詳細全文を読む スポンサード リンク
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