[Structure: see text] Bis(phosphine)boroniumsalts 3a-c were designed and prepared as key building blocks for the synthesis of highly congested diphosphinobenzenes. The preparation of sterically hindered ortho-phenylene-bridged diphosphines 1a-c was achieved by the reaction of the bis(phosphine)boroniumsalts 3a-c with difluorobenzenechromium complex 2 and subsequent removal of the BH2 group. The steric