- Stability of the cyclobutenyl group in Fe(C=CFCF2CF2)(CO)2(η-C5H5) towards isomerisation by ring-opening. X-ray crystal structures of Fe(C=CFCF2CF2)(CO)(L)(η-C5H5) (L=CO and PPh3)
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The perfluorocyclobutenyl-iron complex Fe(c-C4F5)(CO)2(η-C5H5) does not undergo ring-opening isomerisation to a buta-1,3-dien-2-yl derivative either on pyrolysis or on UV irradiation.This difference from related cyano-cyclobutenyl complexes, and from cyclobutenes in general, has been traced, by a structural study of the complexes Fe(C=CFCF2CF2)(CO)(L)(η-C5H5) (L=CO (1a), PPh3 (1c)), to a shorter (and therefore stronger) C-C bond opposite the C=C double bond, i.e. the bond that would be broken in the isomerisation reaction.Crystals of 1a are monoclinic, space group P21/n, with unit cell dimensions a 6.437(1), b 15.864(4), c 11.585(3) Angstroem and β 96.54(2) deg, with Z=4.Crystals of 1c are triclinic, space group P, with cell parameters a 9.358(8), b 14.890(5), c 17.865(4) Angstroem, α 103.37(3), β 95.06(4), γ 91.13(5) deg, Z=4.Both structures was refined by full-matrix least-squares methods to final R of 0.041 and 0.072, for 766 and 2472 reflections with I>2.5?(I), for 1a and 1c, respectively.
- Bruce, Michael I.,Liddell, Michael J.,Snow, Michael R.,Tiekink, Edward R. T.
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- "Through-space" spin-spin coupling between thallium and hydrogen in o-alkylphenylthallium compounds
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In this study a comparison was made of the Tl...H sidechain coupling constants for mono- and di-arylthallium derivatives in which a series of alkyl groups (CH3, C2H5, i-C3H7, t-C4H9) are 0- and p- to the thallium atom.The results provide evidence of "through-space" coupling between thallium and hydrogen in some of the o-alkylphenylthallium compounds, with the"through-space" contribution to 5J(Tl...C(CH3)3 in the o-tert-butylphenylthallium derivatives being considerable.
- Cheesman, Bruce Victor,White, Raymond Frederick Martin
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p. 521 - 525
(2007/10/02)
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