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.