CdOH42

CdOH42 is a chemical formula encountered in inorganic chemistry, typically interpreted as a tetrahydroxo cadmium species. In most discussions, it corresponds to the dianionic complex [Cd(OH)4]2− that can form salts with counterions in solution or the solid state. The unit is mainly studied within coordination chemistry and hydrolysis chemistry of cadmium(II).

The [Cd(OH)4]2− anion is described as a tetrahedral coordination around the Cd(II) center, with four hydroxide ligands arranged around the metal. The exact geometry can be influenced by hydrogen bonding and the identity of the counterions, leading to distorted arrangements in crystals or in solution.

In aqueous solution, treating a soluble cadmium(II) salt with excess hydroxide can lead to deprotonation and formation of [Cd(OH)4]2−. Crystallization of solid salts often requires appropriate counterions, giving compounds such as Na2[Cd(OH)4] or K2[Cd(OH)4], depending on the chosen base and crystallization conditions.

The dianionic complex is typically highly soluble in water as a basic solution; it is sensitive to pH and can convert to Cd(OH)2 or other hydroxo species upon dilution or warming. Like all cadmium compounds, CdOH42 is toxic and should be handled with appropriate safety precautions.

Cd hydroxide/hydroxo complexes are mainly of interest for fundamental coordination chemistry and studies of metal-hydroxide bonding. Cadmium compounds pose health risks, including carcinogenicity; use of proper PPE, a fume hood, and waste disposal per hazardous-material guidelines is required.