Complexes of Thiazyl Halides NSX X F, Cl, Br , NSF3 and the Anion

5 Complexes of Thiazyl Halides NSX (X = F, Cl, Br), NSF3 and the [NSF2] Anion 

Monomeric thiazyl halides NSX (X = F, Cl Br) have been characterized in the gas phase, but oligomerization to cyclic species, e.g., (NSX)3 (X = F, Cl) and (NSF)4, occurs in the condensed phase (Section 8.7). These ligands can be stabilized, however, by coordination to a transition metal. The NSF complexes are conveniently prepared in SO2 (Eq. 1.6) The monomeric fluoride NSF is conveniently generated in situ by thermal decomposition of FC(0)NSF2 or Hg(NSp2)2 (Section 8.2). 

The IR stretching frequencies o(SN) and o(SF) occur at higher wave numbers and the S-N and S-F distances are significantly shorter in the octahedral cations [M(NSF)6] than those in the free ligand, indicating an increase in S-N and S-F bond strength upon coordination. 

The conversion of coordinated NSCI into a nitrido ligand provides a useful synthesis of transition-metal nitrides. For example, treatment of ReCl4(NSCl)(POCl3) with triphenylphosphine generates the nitrido complex ReNClaCPPhsla.  

Thiazyl trifluoride NSF3 is more thermally stable and easier to handle than NSF (Section 8.3). It can be introduced into transition-metal complexes by SO2 displacement reactions (Eq. 7.8). An alternative route to metal-NSF3 complexes is shown in Eq. 7.9. 

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