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

A simultaneous electron diffraction and mass spectrometric experiment was performed to investigate erbium trichloride vapor at 1134(20) K. The vapor contains 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) å, r_g(Cl-Cl) 4.036(19) å, effective angle CIErCl 112.3(1.2)?; with vibrational corrections included, these values correspond to the pyramidal equilibrium configuration of the molecule. For the dimer, a stmcture of D_2h, symmetry with four bridging bonds was adopted and the following parameters were found: r_g(Er-Cl₁) 2.444(5) å, r_g(Er-Cl_h) 2.65(4) å, ∠Cl₁-Er-Cl₁ 117(5)°, ∠Cl_b-Er-Cl_b 84(10)°.