Diphosphane adopts the gauche conformation (like hydrazine, less symmetrical than shown in the image) with a P−P distance of 2.219 angstroms.According to an optimized procedure, hydrolysis of 400 g of CaP at −30 °C gives about 20 g of product, slightly contaminated with phosphine.Reaction of diphosphane with butyllithium affords a variety of condensed polyphosphine compounds.Otherwise, the substituents facily redistribute on the phosphorus centers to give a mixture of products.Symmetric diphosphanes are easily prepared by reductive coupling, e.g. tetraphenyldiphosphine from chlorodiphenylphosphine: Ultraviolet radiation decomposes mercury(II) dialkylphosphides to the metal and a dialkylphosphane.