T. Iijima, T. Kondou, T. Takenaka
Apr 6, 1998
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Journal
Journal of Molecular Structure
Abstract
Abstract The structural parameters of the title compounds have been determined by gas-phase electron diffraction at room temperature. Distances in rg and angles in θα with limits of error in parentheses are for isopropylamine CC 1.529(5) A, CN 1.469(13)A, CCC 114.4(16)°, CCN 108.9(9)° and CCH (methyl) 111.1(32)° for cyclopropylamine C1C2,3 1.514(3) A, CN 1.429(8) A and CCN 117.2(6)°. The parameters have been further refined by combined use of the moments of inertia from microwave literature. It has been shown that the cyclopropyl CN distance is shorter than the methylamine CN distance, but that the isopropyl CN distance is almost equal to the methylamine distance. The latter is in contradiction to the trend found in the similar series of chlorides and bromides, that is, longer CX distances as compared with the methyl CX distances. It has also been noted that there is apparent discrepancy between the r0α-structure determined by the present study and the reported rs-structure of cyclopropylamine in the CN, NH distances and the CNH angle. This is an indication that bending motions in the amino group are rather anharmonic.