Hydrated and Solvated Tin(II) Ions in Solution and the Solid State, and a Coordination Chemistry Overview of the d10s2 Metal Ions.

The coordination chemistry of d¹⁰s² metal ions is strongly affected by an (at least partially) occupied d¹⁰s² metal ion-ligand atom antibonding orbital, which may cause a void in the coordination sphere due to repulsion between the electrons in the antibonding orbital on the metal ion and those on the ligands. The character of the formed d¹⁰s² metal ion-ligand atom bond plays an important role in the electron density in the antibonding orbital and thereby also in the coordination chemistry. The hydrated tin(II) ion, [Sn(H₂O)₃]²⁺, and the trihydroxidostannate ion, [Sn(OH)₃]⁻, have very different mean Sn−O bond lengths (2.21 and 2.08 Å, respectively) and O-Sn-O angles (ca. 78 and 90°, respectively) both in the solid state and in solution. On increasing the covalency of the tin(II)-ligand bonds, the repulsion decreases and higher coordination numbers are obtained, as seen in the dimethylsulfoxide- and N,N-dimethylthioformamide-solvated tin(II) ions, both of which are five-coordinate with square-pyramidal structures. [ABSTRACT FROM AUTHOR]