Disulfur dinitride

Preparation and reactions

Passing gaseous over silver metal wool at 250–300 °C at low pressure (1 mmHg) yields cyclic . The silver reacts with the sulfur produced by the thermal decomposition of the to form , and the resulting catalyzes the conversion of the remaining into the four-membered ring , : : An alternative uses the less explosive .

decomposes explosively above 30°C, and is shock sensitive. It readily sublimes, and is soluble in diethyl ether. Traces of water cause it to polymerize into . In the solid state it spontaneously polymerizes forming . It forms adducts with Lewis acids via a nitrogen atom, e.g. , , , .

Structure and bonding

The molecule is a four-membered ring, with alternating S and N atoms. The molecule is a resonance hybrid of many contributing structures. In one of those structures, one S atom has valence 4 and the other S atom has valence 2, and both N atoms have valence 3. In the other structure both S atoms have valence 2 and both N atoms have valence 3, and one of the S atoms has a charge of +1, and one of the N atoms has a charge of −1. The molecule is almost square and planar. The S–N bond lengths are 165.1 pm and 165.7 pm and the bond angles are very close to 90°. The molecule is isoelectronic with the cyclic dication and has 6π electrons. The bonding has been investigated using a spin-coupled valence bond method and is described as having four framework sigma bonds, with the N atoms bearing a high negative charge and the S atoms a corresponding positive charge. Two π electrons from the sulfur atoms are coupled across the ring making the molecule overall a singlet diradical.

References

References

1. {{Greenwood&Earnshaw
2. (2001). "Inorganic Chemistry". Elsevier.
3. (1969). "The Crystal and Molecular Structure of S₂N₂(SbCl₅)₂". Inorganic Chemistry.
4. (1996). "The Extraordinary Electronic Structure of N₂S₂". Journal of the American Chemical Society.