N.m.r. spectra of α-tetraphosphorus trisulphide isothiocyanates: extreme broadening of phosphorus-31 absorptions by nitrogen-14 and large phosphorus–nitrogen coupling constants

Abstract

The collapse of the P_B parts of the ³¹P n.m.r. spectra of α-P₄S₃(¹⁴NCS)₂(1a), α-P₄S₃(¹⁴NCS)I (2a), and α-P₄S₃(¹⁴NCS)Cl (3a) at room temperature is due to ¹⁴N relaxation effects rather than to chemical exchange, as shown by analysis of the spectra of the corresponding ¹⁵N isotopomers (1b), (2b), and (3b), which show very large ¹J_PN coupling constants.