Molecular structure of erbium trichloride monomer and dimer by electron diffraction and mass spectrometric data

A simultaneous electron diffraction and mass spectrometric experiment was p erformed to investigate erbium trichloride vapor at 1134(20) K. The vapor c ontains 97(2) mol. % monomer and 3(2) mol. % dimer. For the ErCl3 molecule, the following parameters were found: r(g)(Er-Cl) 2.430(5) Angstrom, r(g)(C l-Cl) 4.036(19) Angstrom, effective angle ClErCl 112.3(1.2)degrees; with vi brational corrections included, these values correspond to the pyramidal eq uilibrium configuration of the molecule. For the dimer, a structure of D-2h symmetry with four bridging bonds was adopted and the following parameters were found: r(g)(Er-Cl-t) 2.444(5) Angstrom, r(g)(Er-Cl-b) 2.65(4) Angstro m, angle Cl-t-Er-Cl-b 117(5)degrees, angle Cl-b-Er-Cl-b 84(10)degrees.