Electronic structure calculations combining the local-density approximation with an exact diagonalization of the Anderson impurity model show an intermediate 5f5-5f6-valence ground state and delocalization of the 5f5 multiplet of the Pu atom 5f shell in PuCoIn5, PuCoGa5, and δ-Pu. The 5f local magnetic moment is compensated by a moment formed in the surrounding cloud of conduction electrons. For PuCoGa5 and δ-Pu the compensation is complete, and the Anderson impurity ground state is a singlet. For PuCoIn5 the compensation is partial, and the Pu ground state is magnetic. We suggest that the unconventional d-wave superconductivity is likely mediated by the 5f-state antiferromagnetic fluctuations in PuCoIn5 and by valence fluctuations in PuCoGa5.