Arene complexes of the form TpM(pi-acid)(L)(eta(2)-arene) (Tp = hydridotris (pyrazolyl) borate, M = Re, Mo, or W, pi-acid = CO or NO, L = 1-alkylimidazole, pyridine, PMe3, arene is prochiral) exist as a dynamic equilibrium of coordination diastereomers in solution. In both crystalline and amorphous solid states, however, only one diastereomer is present. Reactions on the bound arenes in these complexes have been performed stereoselectively, by exploiting the homomorphic nature of the solid phase.