The electric deflection of mass spectrometrically detected molecular beams has been used to study the molecular geometry of high temperature species by determining whether they possess permanent dipole moments or not, By this means it has been shown that (1) the lithium halide dimers are planar; ( 2 ) lithium oxide, LinO, is linear;( 3 ) the beryllium and magnesium dihalides are linear: the barium dihalides are bent; (4) the group IIB dihalides are linear; ( 5 ) the dihalides of the transition metals from manganese through copper are linear; ( 6 ) the lead dihalides are bent.Many of the structural results are in disagreement with the prediction of simple theories of molecular geometry.Both PbI and Pb12 were found in lead iodide vapor.

The deflection of mass spectrometrically detected beams of CaF2, MnF2, MnCl2, CoF2, NiF2, CuF2, ZnF2, ZnCl2, and HgCl2 by an inhomogeneous electric field has been examined. As found previously, CaF2 deflects in the manner expected for a polar molecule. The remaining molecules listed were found to be nonpolar. These observations are interpreted to imply that while CaF2 has a nonlinear equilibrium geometry the remaining species are linear. The result for HgCl2 is in agreement with a number of previous electron diffraction and spectroscopic studies.

A conventional Inghram-type mass spectrometer has been adapted to permit the study of the polarity of high-temperature species by electric-deflection methods. The molecule Li.O has been found to be nonpolar and therefore to have an equilibrium angle close to 180°, as shown by the absence of deflection of a molecular beam by an inhomogeneous electric field. The species LiO, which was found by Berkowitz, Chupka, Blue, and Margrave, has been confirmed to form a small percentage of the vapor in equilibrium with solid Li.O. Gaseous lithium molybdate, Li.MoO" has been observed. It is readily formed by the reaction of lithium oxide with molybdenum above 1150°C.

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Notes 4139 to BTMA, has a higher moment although deviation from a smooth curve in its susceptibility-temperature characteristic may reflect relatively large changes in the effective ligand field with temperature. Indeed, the increasing divergence of the susceptibilities of all the compounds studied with increasing temperature suggest that the ligand field strength and/or symmetry is markedly temperature dependent. In view of the complexity of the crystal structure, this behavior is not surprising.