Some INDO calculations of the dependence of one‐bond phosphorus‐phosphorus coupling upon molecular geometry

Some INDO parameterized SCPT calculations of 1 J (PP) and 1 J (PP) are reported as a function of geometry. At structures corresponding to the gas‐phase equilibrium configuration of diphosphine, all of the substituted diphosphines considered are predicted to have negative values of 1 J (PP). Both contact and non‐contact contributions to 1 J (PP) are significant, whereas the angular variation of 1 J (PP) is mainly due to the contact term. The non‐contact interactions are dominant in determining the value of 1 J (PP).