Disulfur dinitride
Encyclopedia
Disulfur dinitride is the chemical compound S2N2 with a cyclic square planar structure.
over silver
metal wool at 250-300°C at low pressure (1mm Hg) yields cyclic S2N2. The silver
reacts with the sulfur produced by the thermal decomposition of the S4N4 to form Ag2S
, and the resulting Ag2S
catalyzes the conversion of the S4N4 into the four-membered ring S2N2,
An alternative uses the less explosive S4N3Cl.
S2N2 decomposes explosively above 30°, and is shock sensitive. It readily sublimes, insoluble in water, soluble in diethyl ether
and traces of water cause it to polymerise into S4N4
. In the solid state it spontaneously polymerizes forming (SN)x
. It forms adducts with Lewis acids via a nitrogen atom, e.g. S2N2.BCl3, S2N2.2AlCl3, S2N2.SbCl5, S2N2.2SbCl5.
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
.
Preparation and reactions
Passing gaseous S4N4Tetrasulfur tetranitride
Tetrasulfur tetranitride is an inorganic compound with the formula S4N4. This gold-poppy coloured solid is the most important binary sulfur nitride, which are compounds that contain only the elements sulfur and nitrogen. It is a precursor to many S-N compounds and has attracted wide interest for...
over silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
metal wool at 250-300°C at low pressure (1mm Hg) yields cyclic S2N2. The silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
reacts with the sulfur produced by the thermal decomposition of the S4N4 to form Ag2S
Silver sulfide
Silver sulfide, Ag2S, is the sulfide of silver. This dense black solid constitutes the tarnish that forms over time on silverware and other silver objects. Silver sulfide is insoluble in all solvents, but is degraded by strong acids. Silver sulfide features a covalent bond, as it is made up of...
, and the resulting Ag2S
Silver sulfide
Silver sulfide, Ag2S, is the sulfide of silver. This dense black solid constitutes the tarnish that forms over time on silverware and other silver objects. Silver sulfide is insoluble in all solvents, but is degraded by strong acids. Silver sulfide features a covalent bond, as it is made up of...
catalyzes the conversion of the S4N4 into the four-membered ring S2N2,
- S4N4 + 8 Ag → 4 Ag2SSilver sulfideSilver sulfide, Ag2S, is the sulfide of silver. This dense black solid constitutes the tarnish that forms over time on silverware and other silver objects. Silver sulfide is insoluble in all solvents, but is degraded by strong acids. Silver sulfide features a covalent bond, as it is made up of...
+ 2 N2 - S4N4 → 2S2N2
An alternative uses the less explosive S4N3Cl.
S2N2 decomposes explosively above 30°, and is shock sensitive. It readily sublimes, insoluble in water, soluble in diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
and traces of water cause it to polymerise into S4N4
Tetrasulfur tetranitride
Tetrasulfur tetranitride is an inorganic compound with the formula S4N4. This gold-poppy coloured solid is the most important binary sulfur nitride, which are compounds that contain only the elements sulfur and nitrogen. It is a precursor to many S-N compounds and has attracted wide interest for...
. In the solid state it spontaneously polymerizes forming (SN)x
Polythiazyl
Polythiazyl , x, was the first conducting inorganic polymer. In addition to being an electrical conductor, it was also found to be a superconductor at very low temperatures .-Structure and bonding:...
. It forms adducts with Lewis acids via a nitrogen atom, e.g. S2N2.BCl3, S2N2.2AlCl3, S2N2.SbCl5, S2N2.2SbCl5.
Structure and bonding
The S2N2 molecule is virtually square and planar. The S-N bond lengths are 165.1pm and 165.7pm and the bond angles are very close to 90. The S2N2 molecule is isoelectronic with the S42+ and has 6π electrons. The bonding has been investigated using a spin-coupled valence bondModern valence bond theory
Modern valence bond theory is the term used to describe applications of valence bond theory with computer programs that are competitive in accuracy and economy with programs for the Hartree-Fock method and other molecular orbital based methods. The latter methods dominated quantum chemistry from...
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
Diradical
A diradical in organic chemistry is a molecular species with two electrons occupying two degenerate molecular orbitals . They are known by their higher reactivities and shorter lifetimes. In a broader definition diradicals are even-electron molecules that have one bond less than the number...
.