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)2][cis-Pd2+(PEt3)22-OSO2CF3]]