Selective Preparation of the [3,5-tBu2-1,2,4-C2P3]− Ion and Synthesis and Structure of the Cationic Species nido-[3,5-tBu2-1,2,4-C2P3]+, Isoelectronic with [C5R5]

Building pyramids: The first P–C cluster, namely, the novel nido species 2, is readily prepared from 1 (•=CtBu), which is also an excellent precursor for the selective synthesis of the anion 3. DFT calculations show that there is a switch in the global minimum, on the introduction of three P atoms (${-\ominus \rightarrow}$CH) into the [C5H5]+ ion, from cyclic‐unsaturated to saturated cage species, such as 2.