31P–31P spin–spin coupling constants for pnicogen homodimers

Ab initio calculations have been carried out in a systematic investigation of pnicogen homodimers (PH2X)2, for X = F, OH, NC, NH2, CCH, CN, CH3, H, and BH2. Complex binding energies range from 7 to 34 kJ mol−1, which is within the range observed for neutral hydrogen-bonded complexes. One-bond spin–spin coupling constants across the pnicogen interaction 1pJ(P–P) exhibit a quadratic dependence on the P–P distance, similar to the dependence of 2hJ(X–Y) on the X–Y distance for complexes with X–H⋯Y hydrogen bonds. Thus, computed values of 1pJ(P–P) could be used to extract P–P distances from experimentally measured coupling constants.