Selective Preparation of the [3,5‐ t Bu 2 ‐1,2,4‐C 2 P 3 ] − Ion and Synthesis and Structure of the Cationic Species nido ‐[3,5‐ t Bu 2 ‐1,2,4‐C 2 P 3 ] + , Isoelectronic with [C 5 R 5 ] +

Building pyramids : The first P–C cluster, namely, the novel nido species 2 , is readily prepared from 1 (•=C t Bu), 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 [C 5 H 5 ] + ion, from cyclic‐unsaturated to saturated cage species, such as 2 .