Phosphorus-31 nuclear magnetic resonance parameters for amino compounds with the α-tetraphosphorus trisulphide skelton

Abstract

Phosphorus-31 NMR spectra have been recorded and assigned for α-P₄S₃X₂1 and α-P₄S₃X(Y)2(X = NMe₂, NEt₂, NMePh, NEtPh, or NPh₂; Y = I), and for a mixed-amino compound 2(X = NPh₂, Y = NEt₂). All compounds were unstable and were not isolated. For the symmetric molecules 1(X = NRR′) the ²J(PP) couplings were generally much less positive, the ¹J(PP) couplings were much more negative, and the bridgehead chemical shifts were to lower frequency, than for other α-P₄S₃ compounds reported previously. New predictive relationships between NMR parameters for unsymmetric compounds and those for symmetric compounds have been found. The ¹J(PP) coupling along opposite edges of the P₄ cage of the unsymmetric compounds α-P₄S₃X(Y) deviated from values for the corresponding symmetric compounds (α-P₄S₃X₂ and α-P₄S₃Y₂) by similar but opposite amounts. Chemical shifts of the two bridgehead phosphorus nuclei similarly showed approximately equal and opposite deviations from the shifts found for the symmetric compounds.