Protonenresonanz-Spektroskopie ungesättigter Ringsysteme V

Abstract

The nmr-spectrum of cycloheptatriene- (1.3.5) -molybdenumtricarbonyl (II) has been analyzed in terms of chemical shifts and coupling constants using sub-spectral and computer analysis. The results of a refined analysis for cycloheptatriene-(1.3.5) (I) are given. Coupling parameters for both systems are discussed with respect to structural data obtained earlier by x-ray-analysis, electrondiffraction measurements and microwave spectroscopy. The dependence of J 23 on the planarity of the triene system is confirmed. Evidence is cited, that in solution the angle α for I is greater than 47°. The relative chemical shifts found for the methylene protons in II are in accord with the anisotropic shielding effect of the double bond.