13 C, 15 N, 29 Si and 31 P NMR study of N ‐trimethylsilylaminophosphorus compounds: Sign determination of coupling constants and application of Hahn‐echo extended pulse sequences

N ‐Trimethylsilylaminophosphorus compounds containing phosphorus in different oxidation states [P(III) and P(V)] and with different coordination numbers (2, 3 or 4) were studied by 13 C, 14 N, 29 Si and 31 P NMR, using a variety of one‐ and two‐dimensional (2D) techniques, including Hahn‐echo extended (HEED) pulse sequences. These techniques were demonstrated by the determination of the signs of all coupling constants involving the 1 H, 13 C, 15 N, 29 Si and 31 P nuclei in bis(trimethylsilyl)aminodimethylphosphane (1). Appropriate experiments, including inverse 2D 1 H{ 15 N} correlations, were performed for the other compounds in order to determine the signs of the coupling constants. A geometric dependence of 2 J ( 31 P, N, 29 Si) was proved for bis(trimethylsilyl)amino( tert ‐butyl)chlorophosphane (2c), where large negative 2 J ( 31 P, 29 Si) and a small positive 2 J ( 31 P, 29 Si) values, indicate syn and anti orientations, respectively, of the NSi bond relative to the phosphorus lone pair of electrons. The HEED pulse sequences allow the rapid determination of isotope‐induced shifts, 1 δ 15/14 N( 31 P), as shown for 1, derivatives of 1 and 2c.