Calculated lanthanide contractions for molecular trihalides and fully hydrated ions: The contributions from relativity and 4f-shell hybridization

The calculated lanthanide contraction in the title systems is typically 18–21 pm of which about 9–23% comes from relativistic effects. A pronounced 4f hybridization is found for LuF3 using three different relativistic methods of calculation. Large lanthanide nuclear quadrupole coupling constants are predicted for the molecular trihalides.