The Extraordinary Electronic Structure of N2S2

The electronic structure and bonding of the N 2 S 2 molecule are studied by the spin-coupled valence bond method. Unusual features are revealed which clarify much of the hitherto puzzling properties of this molecule, leading ultimately to a simple Lewis structure: The two N atoms of the N 2 S 2 ring bear a substantial negative charge, and the two S atoms, a complementary positive charge. There are four single N−S σ bonds and two lone pairs of π electrons, one pair centered about each N atom. Two further π electrons, one from each of the S atoms, are directly coupled to each other across the ring, giving the molecule the overall character of a singlet diradical. This last is shown to be closely related to the metallic character of the (SN) x polymer.