Metalformate

Metalformate refers to salts formed from the formate anion (HCOO−) and a metal cation. The general formula M(HCOO)n describes many compounds in which the metal is typically divalent or trivalent. Common examples include calcium formate Ca(HCOO)2, zinc formate Zn(HCOO)2, copper formate Cu(HCOO)2, manganese formate Mn(HCOO)2, iron(II) formate Fe(HCOO)2, nickel formate Ni(HCOO)2, cobalt formate Co(HCOO)2, and lead formate Pb(HCOO)2. Formates may exist as hydrates or anhydrous solids, and their structures often feature formate ligands bridging multiple metal centers to form one-, two-, or three-dimensional coordination networks.

Preparation of metal formates is typically achieved by reacting a formic-acid solution with a suitable metal salt or base, such as a metal carbonate, oxide, or hydroxide, followed by isolation of the solid. They can also be obtained by metathesis reactions between formate salts and metal salts. The resulting materials generally crystallize as powders or well-defined coordination polymers, with properties dependent on the metal and on hydration state.

Properties of metal formates vary widely. Solubility in water ranges from very soluble (in certain alkali or alkaline-earth cases) to sparingly soluble for many transition-metal formates. Thermal decomposition often yields the corresponding metal oxide with release of carbon dioxide and water; some formates can release carbon monoxide under stronger heating.

Uses of metal formates include serving as precursors to metal oxides and mixed-oxide materials, and as building blocks for coordination polymers and metal–organic frameworks. Calcium formate is widely used as a cement accelerator and as a formic-acid–related chemical precursor; other metal formates are studied for catalytic and material science applications.

Safety considerations follow standard chemical-handling practices. Formate compounds can release formic acid on hydrolysis or heating, and proper precautions should be observed to avoid inhalation, ingestion, or skin and eye contact.