Co3+ and Ir3+ in pure liquid ammonia: Structure and dynamics from ab initio quantum mechanical charge field molecular dynamics

The solvation properties of Co3+ and Ir3+ in pure liquid ammonia have been investigated via ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulations. During the simulation time of 20 ps, octahedral [Co(NH3)6]3+ and [Ir(NH3)6]3+ complexes were formed in the first solvation shell without the occurance of ligand exchange. The respective average first shell ion distance of Co3+ and Ir3+ were found to be 2.07 and 2.18 Å, respectively. The solvation properties in the first shells of each system are found in excellent agreement with experimental data. A number of ligands were exchanged between the second solvation shell and the bulk phase in both systems along the simulation. The associated mean residence times of NH3 ligands in the second shell are 3.06 and 2.47 ps for Co3+ and Ir3+, respectively.