Abstract
The energy difference (Δ__E__) between the two types of rotamers of β‐methoxyethylmercuric chloride has been satisfactorily determined by only assuming the ratio of vicinal trans and gauche HH coupling constants. The validity of the result was confirmed by the large temperature dependence of the vicinal HgH couplings in various solvents. Moreover, it has become possible to determine small values of Δ__E__ in nonpolar solvents. Two Δ__E__ values of β‐methoxypropylmercuric chloride in various solvents were determined on the basis of the substituent electronegativity effect on the HH couplings and their validity was supported by the large temperature dependence of the vicinal HgH couplings. With regard to erythro‐ and threo‐(α‐methyl‐β‐methoxy)propylmercuric chlorides, both the HH and HgH couplings were used to estimate the values of Δ__E__ among the rotamers. Throughout the mercury compounds, it was ascertained that the more polar the solvent, the greater the preference for the conformation with the trans disposed HgCl and OCH~3~ groups. Excellent agreement between the observed facts and the calculations by extended Hückel theory were shown with regard to the relative magnitude of the rotamer polarity and the conformational energy difference of these mercury compounds.