Disulfur dinitride is the chemical compound with the formula .
Passing gaseous over silver metal wool at 250âÂÂ300 ðC 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 30ðC, 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. , , , .
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 âÂÂ1. The molecule is almost square and planar. The SâÂÂN bond lengths are 165.1 pm and 165.7 pm and the bond angles are very close to 90ð. The molecule is isoelectronic with the cyclic dication and has 6àelectrons. 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 àelectrons from the sulfur atoms are coupled across the ring making the molecule overall a singlet diradical.