Thiazyl fluoride

Lewis acids remove fluoride to afford thiazyl salts:^[6]

NSF + BF₃ → [N≡S]⁺[BF₄]⁻

Thiazyl fluoride functions as a ligand in [Re(CO)₅NSF]⁺.^[1] and [M(NSF)₆]²⁺ (M = Co, Ni). In all of its complexes, NSF is bound to the metal center through nitrogen.^[7]

Thiazyl fluoride reacts violently with water:^[8]

NSF + 2 H₂O → SO₂ + HF + NH₃

Nucleophilic attack on thiazyl fluoride occurs at sulfur atom:.^[9]

NS−F + Nu⁻ → NS−Nu + F⁻

Fluoride gives an adduct:

NS−F + F⁻ → NSF−2

The halogen derivatives X−N=SF₂ (X = F, Cl, Br, I) can be synthesized from reacting Hg(NSF)₂ with X₂; whereby, ClNSF₂ is the most stable compound observed in this series.^[10]

At room temperature, thiazyl fluoride trimerizes:

In the product 1,3,5-trifluoro-1λ⁴,3λ⁴,5λ⁴-2,4,6-trithiatriazine, each sulfur atom remains tetravalent.

Thiazyl fluoride also participates in cycloaddition in the presence of dienes.

The N−S bond length is 1.448 Å, which is short, indicating multiple bonding, and can be represented by the following resonance structures:

The NSF molecule has 18 total valence electrons and is isoelectronic to sulfur dioxide. Thiazyl fluoride adopts C_s-symmetry and has been shown by isotopic substitution to be bent in the ground state.^[11][12] A combination of rotational analysis with Franck-Condon calculations has been applied to study the electronic excitation from the A''${\displaystyle -}$A' states, which results in the elongation of the nitrogen-sulfur bond by 0.11 Å and a decrease in the ${\displaystyle \measuredangle }$NSF by 15.3${\displaystyle ^{\circ }}$.