THE BINDING-ENERGIES OF ONE AND 2 WATER-MOLECULES TO THE 1ST TRANSITION-ROW METAL POSITIVE-IONS .2.

The binding energy of H2O to transition-metal ions is determined not only by the electrostatic interaction, but by 4s4p and 3d 4s hybridization and by 4s to 3d promotion on the metal. All of the M(H2O) 2+ systems are linear except for Mn(H2O) 2+ and Zn(H2O)2+, which we show to be bent with 7A1 and 2A1 ground states, respectively. The O-Mn-O bond angle is 94° and the O-Zn-O bond angle is 99°. These systems bend to allow 4s4p hybridization, which reduces the repulsion. For Mn+, the 3d n4s1-3d n+1 separation is too large to allow 3d 4s hybridization or 4s to 3d promotion. For Zn+ the ground-state 3d 104s1 occupation precludes 4s to 3d promotion or 3d 4s hybridization. © 1990 American Institute of Physics.