Changes in the inner coordination sphere as the primary chemical act of excited Gd3+aq

Abstract

Photoexcited Gd(OH2)3+8 frees two water molecules to give *Gd(OH2)3+6 in an entropy-controlled process (ΔSO ∼ 9.5 cal/mol deg, ΔHO ∼ 0.32 kcal/mol, ΔGO ∼ -2.5 kcal/mol) and secondary excited-state processes. This inner-sphere change may be rationalised by different 4f-shell contraction and 5p-shell expansion in the lowest and excited levels of the 4f7 configuration. © 1982.