Pentasulfur dinitride, a fascinating inorganic compound, has captivated the interest of chemists due to its unique properties. This article delves into the chemical formula of pentasulfur dinitride, exploring its composition, structure, and significance.

Pentasulfur dinitride, represented by the chemical formula S5N2, is a polyatomic molecule composed of five sulfur atoms and two nitrogen atoms. The sulfur atoms are arranged in a trigonal bipyramidal structure, with the two nitrogen atoms occupying two of the equatorial positions. The S-S bond lengths vary slightly, ranging from 2.05 to 2.12 Å, indicating some degree of bond localization. The S-N bond lengths, on the other hand, are uniform at 1.72 Å, suggesting double-bond character.

The chemical formula for pentasulfur dinitride highlights the unique stoichiometry of this compound. The presence of five sulfur atoms and two nitrogen atoms gives it an empirical formula of S2.5N. However, this formula does not accurately represent the actual molecular structure. The polyatomic molecule consists of discrete S5N2 units, indicating that the molecular formula is more appropriate than the empirical formula.

Structure of Pentasulfur Dinitride

Trigonal Bipyramidal Geometry

Pentasulfur dinitride adopts a trigonal bipyramidal molecular geometry. The sulfur atoms occupy the vertices of a trigonal bipyramid, with the two nitrogen atoms positioned in two of the equatorial positions. This geometry arises from the hybridization of the sulfur atoms, which adopt sp3d hybridization. The two unhybridized p orbitals of each sulfur atom overlap laterally to form the S-S bonds, resulting in the trigonal bipyramidal structure.

Bonding Interactions

The bonding within pentasulfur dinitride is complex and involves several types of interactions. The S-S bonds are predominantly covalent, with some degree of bond localization. The S-N bonds, however, exhibit double-bond character, indicating a significant contribution from π-bonding. Additionally, there are weak intermolecular interactions between the S5N2 molecules, which contribute to the overall stability of the compound.

Properties of Pentasulfur Dinitride

Physical Appearance

Pentasulfur dinitride is a bright yellow solid at room temperature. It is insoluble in water but soluble in nonpolar organic solvents such as benzene and carbon tetrachloride. The compound exhibits a pungent odor and is highly reactive, readily reacting with water and other protic solvents.

Chemical Reactivity

Pentasulfur dinitride is a highly reactive compound due to the presence of multiple sulfur-nitrogen bonds. It reacts readily with water, releasing hydrogen sulfide and sulfur dioxide gases. The compound also reacts with alcohols and amines, forming the corresponding thioamides and iminothioamides. Additionally, pentasulfur dinitride is a potent oxidizing agent and can react with reducing agents to form sulfur compounds.

Applications of Pentasulfur Dinitride

Adhesive and Sealant Industry

Pentasulfur dinitride finds applications in the adhesive and sealant industry as a curing agent for polysulfide polymers. The reaction between pentasulfur dinitride and polysulfide polymers results in the formation of strong and durable cross-links, enhancing the adhesive and sealing properties of the final product.

Polymer Synthesis

Pentasulfur dinitride is used as a reagent in the synthesis of various polymers, including poly(thioamides) and poly(iminothioamides). These polymers exhibit unique properties such as high thermal stability, chemical resistance, and electrical conductivity, making them useful in a variety of applications, including aerospace, electronics, and biomedical devices.


The chemical formula for pentasulfur dinitride, S5N2, accurately represents the composition of this fascinating inorganic compound. The unique trigonal bipyramidal geometry, complex bonding interactions, and high reactivity of pentasulfur dinitride make it a valuable material in various applications, including the adhesive and sealant industry and polymer synthesis. Understanding the chemical formula and properties of pentasulfur dinitride is essential for harnessing its potential and unlocking new frontiers in materials science and technology.



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