Tieftemperatur 13C-NMR.-Spektren von 13C-und 6Li-markierten Chlor-, Brom- und Jod-Lithium-Carbenoiden. Vorläufige Mitteilung

Low Temperature ¹³C-NMR. Spectra of ¹³C- and ⁶Li-Labelled Chloro-, Bromo-, and Iodo-lithiumcarbenoids The ¹³C-NMR. spectra of tetrahydrofuran solutions of 16 chloro-, bromo-, and iodo-⁶lithio- and -⁷lithio-carbenoids with ¹³C-labelled methane, ethane, ethylene, and cyclopropane C-skeletons have been measured at temperatures around ? 100° (for examples see Fig. 1 and 2). Invariably, the exchange of hydrogen or halogen by lithium causes deshielding (Δδ, see Table 1) of the ¹³C-signal by up to 289 and 434 ppm, respectively, and decrease of ¹J (¹H, ¹³C) and ¹J(¹³C,¹³C) couplings (see Table 2) with the C-atom of up to 104 and 30 Hz, respectively. The ¹J(⁶Li, ¹³C) and ¹J(⁷Li, ¹³C) coupling of ca. 17 and 45 Hz, respectively, obtained in ten cases (Table 1) is independant of the substitution pattern of the C-skeleton and of the particular halogen atom.