[en] We have observed isomeric states in ²¹²Rn with very high angular momenta (up to J sup(π) = 30⁺). In a comprehensive series of experiments we have measured lifetimes, excitation functions, angular distributions, linear polarizations, and g factors for γ transitions following the ²⁰⁴Hg(¹³C, 5n)²¹²Rn reaction. We conclude that the four isomers of highest spin contain core-excited neutron configurations, the spins of which are strongly aligned with those of the valence protons. The isomerism appears to result from a lowering of the excitation energies by 1 to 2 MeV compared to a sum of the unperturbed values for the constituent configurations. (author)