Über die Temperaturabhängigkeit der 13C-NMR.-Spektren von [5–6-η-(1Z, 5E)-Cyclooctadien]tetracarbonyleisen und (1Z, 5E)-Cyclooctadien

✍ Scribed by Martin Von Büren; Pius Bischofberger; Hans-Jürgen Hansen

• Publisher: John Wiley and Sons
• Year: 1978
• Tongue: German
• Weight: 386 KB
• Volume: 61
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19780610517

✦ Synopsis

On the Temperature Dependence of the ^13^C‐NMR. Spectra of [5‐6‐η‐(1Z,5E)‐Cyclooctadien] and of (lZ, 5E)‐Cyclooctadiene

The activation parameters of the conformational ring inversion process (simultaneous rotation around the C(3), C(4) and C(7), C(8) bonds; cf. Scheme 1) of the title compounds (1 and 2, respectively) have been determined between 275 L and 155 K by a complete line shape analysis of the temperature dependent proton noise‐modulated decoupled ^13^C‐NMR. spectra of 1 and 2. The temperature dependence of the rates (k(1) and k(2), respectively) of the inversion process can be described by the following equations (no influence of the solvents was observed; E~a~ in J/mol):
. Further data are given in Tables 1 and 2.

The carbonyl groups of the complex 1 show at 180 K, where the ring inversion process is frozen out, a single line at 211 ppm, i. e. the coalescence temperature of the carbonyl groups must be < 180 K.