Synthesis of electron donor–acceptor polyunsaturated methylenepyran Fischer type carbene complexes: dynamic 1H-NMR study and solvatochromic properties

• Published in: Journal of organometallic chemistry Vol. 626; no. 1; pp. 37 - 42
• Main Authors: Robin-Le Guen, F, Le Poul, P, Caro, B, Pichon, R, Kervarec, N
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-04-2001
• Subjects: Methylenepyran carbene complexes; Tungsten and chromium Fischer type carbenes; ‘Push pull’ molecules; Methylenepyran carbene complexes; ‘Push pull’ molecules; Tungsten and chromium Fischer type carbenes
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/S0022-328X(00)00940-2

Condensation of α and γ methylenepyran aldehydes with the Fischer carbene complexes (CO)
5MC(OCH
3)Me (M=Cr, W) or (CO)
5WC(OCH
3)CHCH–CH
3 in the presence of ClSiMe
3/NEt
3 yield donor acceptor complexes, in which the electron donating group is connected to the organometallic accepting group by a conjugated ethylenic spacer.
1H- and
13C-NMR studies, suggest that the carbene fragment and the unsaturated chain lie in the same plan, allowing a mesomeric interaction between the oxygen atom of the heterocycle and the metal via the spacer. The positive solvatochromism of the molecules obtained is reported.