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Strikingly Different Reactivity Patterns of Fischer Alkoxycarbene and Thiocarbene Complexes in Experimental and Theoretical Studies    
Yazarlar
Prof. Dr. Betül KARATAŞ Prof. Dr. Betül KARATAŞ
Türkiye
Isabella Hyla Kryspın
Rudolf Aumann
Özet
Striking differences in the reactions of alkoxycarbene and thiocarbene complexes of chromium and tungsten are observed. Thus, (β-imino) ethoxycarbene complexes 10a-e, generated in situ from [(OC)5W= C(OEt)CH2R] (7a-c; R = n-Pr, Me, c-C7H7) and imidoyl chlorides R1ClC=NCHR2R3 (9a-f; R 1 = t-Bu, Ph, 2-furyl; R2 = H, Me; R3 = Me, Et, Ph), undergo a metalla(di-π-methane) rearrangement to (N-enamino)ethoxycarbene complexes 12a-e, while the corresponding (β--imino)thiocarbene complexes 11a-1, derived from [(OC)5M=C(SEt)CH2R] (8a-e; M = W, Cr; R = n-Pr, Me, c-C7H7, c-C6H7Fe-(CO) 3) and imidoyl chlorides under similar conditions, form pyrroles 16a-h and 17k,l by α-cyclization. On the basis of the calculated DFT/BP86 potential energy surfaces of the particular reaction channels it is shown that (β-imino)alkoxycarbene compounds 10 prefer a metalla(di-α-methane) rearrangement due to the kinetic stability of the (N-enamino)ethoxycarbene products, while formation of pyrroles is not favored due to the presence of high energetic stationary structures in the α-cyclization pathway. For (β-imino)thiocarbene compounds 11, on the other hand, rearranged products are kinetically unstable, and α-cyclization reactions are strongly favored on thermodynamic grounds. © 2007 American Chemical Society.
Anahtar Kelimeler
Makale Türü Özgün Makale
Makale Alt Türü SSCI, AHCI, SCI, SCI-Exp dergilerinde yayımlanan tam makale
Dergi Adı Organometallics
Dergi ISSN 0276-7333
Dergi Tarandığı Indeksler SSCI
Makale Dili İngilizce
Basım Tarihi 09-2007
Cilt No 26
Sayı 20
Sayfalar 4983 / 4996
Doi Numarası 10.1021/om700391t
Makale Linki http://pubs.acs.org/doi/abs/10.1021/om700391t