Molecular Architecture via Coordination:  Self-Assembly, Characterization, and Host−Guest Chemistry of Mixed, Neutral-Charged, Pt−Pt and Pt−Pd Macrocyclic Tetranuclear Complexes. X-ray Crystal Structure of Cyclobis[cis- Pt(dppp)(4-ethynylpyridine)2cis-Pd2+(PEt3)22-OSO2CF3]

Interaction of cis-Ptdppp(p-C6H4CN)2 or cis-Ptdppp(p-C2C6H4N)2 with cis-ML2(OSO2CF3)2 (M = Pt or Pd; L = PEt3 or L2 = dppp), in CH2Cl2 or acetone, at room temperature, results in mixed, neutral-charged cyclic tetranuclear, Pt−Pt or Pt−Pd macrocyclic complexes in 90−99% yields via self-assembly. All tetramers are microcrystalline air- and water-stable solids with decomposition points > 170 °C. The benzonitrile based macrocycles can be disassembled in solution with 4,4‘-bipyridine, while the 4-ethynylpyridine systems are more stable toward a variety of guests. The 4-ethynylpyridine tetramers display host−guest chemistry with silver triflate via the “π -tweezer effect”. The X-ray crystal structure as well as FABMS, including isotope patterns, are reported for the tetranuclear macrocycle cyclobis[cis-Pt(dppp)(4-ethynylpyridine)2cis-Pd2+(PEt3)22-OSO2CF3] (14).