Analysis of charge density in nonaaquagadolinium(III) trifluoromethanesulfonate – insight into GdIII—OH2 bonding

The experimental charge-density distribution in [Gd(H 2 O) 9 ](CF 3 SO 3 ) 3 has been analysed and compared with the theoretical density functional theory calculations. Although the Gd—OH 2 bonds are mainly ionic, a covalent contribution is detectable when inspecting both the topological parameters of these bonds and the natural bond orbital results. This contribution originates from small electron transfer from the lone pairs of oxygen atoms to empty 5 d and 6 s spin orbitals of Gd 3+ .