Depending on the conditions, the reaction of K2PtCl4 with 1,3-bis(N-pyrazolyl) benzene (bpzphH) yields either Pt(bpzph)Cl, [Pt(mu-bpzph)Cl](3), or a mixture of these products. In the case of the C-3-symmetric trimer, each bpzph(-) ligand is bidentate with the metal bonded to a pyrazolyl group and to the phenyl group at the 6 position; the remaining pyrazolyl group bridges to an adjacent platinum center. The crystal structure confirms that each complex is chiral with an unusually deep (similar to 8 angstrom) intramolecular cavity; enantiomeric pairs of trimers encapsulate the diethyl ether solvate. NMR studies establish that the trimer exhibits excellent thermal and kinetic stability. Substitution of the chloride ligands provides a strategy for elaborating the macrocycle.