PentacyanonitrosylferratII

Pentacyanonitrosylferrate(II), also known as sodium nitroprusside, is a coordination complex with the chemical formula Na2[Fe(CN)5NO]. It is a dark red crystalline solid that is soluble in water and ethanol. The compound features an iron(II) ion coordinated to five cyanide ligands and one nitroso ligand. The nitroso ligand is bonded through the nitrogen atom. The complex is considered an inorganic compound.

Historically, sodium nitroprusside was first synthesized by Leopold Gmelin in 1847. It gained significant recognition for its use as a potent and rapid-acting antihypertensive agent. In medicine, it is administered intravenously to manage severe hypertension crises and to induce controlled hypotension during surgery. Its mechanism of action involves the release of nitric oxide (NO) in the bloodstream, which causes vasodilation and a subsequent decrease in blood pressure.

Beyond its pharmaceutical applications, pentacyanonitrosylferrate(II) also finds use as a reagent in analytical chemistry for the detection of sulfhydryl groups, such as those in thiols and cysteine. It reacts with these groups to form a characteristic purple color, allowing for their quantitative determination. The compound is sensitive to light and should be stored accordingly. It is important to note that while beneficial therapeutically, sodium nitroprusside can be toxic if administered improperly due to the potential release of cyanide ions.