Tetra- and Pentaisopropylcyclopentadienyl Complexes of Group 15 Elements

Pentaisopropylcyclopentadienyl dichloropnictogen complexes have been synthesized and studied in solution and in the solid state. The coordination mode of the group 15 element to the Cp ligand varies, with the lighter elements phosphorus and arsenic featuring η1 σ-bonded Cp groups and the heavier elements antimony and bismuth exhibiting η3 and η5 bonded Cp groups, respectively. In the case of ≤η3 bonded Cp groups, a rapid sigmatropic rearrangement is observed at room temperature in solution and was examined by VT-NMR spectroscopy and DFT calculations. Furthermore, bis­(cyclopentadienyl)­diphosphenes with tetra- and pentaisopropylcyclopentadienyl groups could be obtained in good yields from the corresponding dichlorophosphanes, and a related silver­(I) complex of a diphosphene was characterized.