The preparation, characterization, and some chemistry of a series of unique cationic, tetranuclear, Pt(II)- and Pd(II)-based macrocyclic squares are reported. A variety of bidentate ligands (bipyridine, diazapyrene, dicyanobenzene, and dicyanobiphenyl) are interacted with the square-planar cis-bis(phosphine) Pt and Pd bis(triflate) complexes in organic solvents at room temperature, resulting in molecular squares in high isolated yields via self-assembly. All molecular squares are robust air- and water-stable microcrystalline solids with decomposition points mostly above 200 degrees C. They are generally soluble in polar organic solvents but not in water or nonpolar solvents like pentane, toluene, and ether. The cyano-based macrocycles are highly fluxional in solution, whereas the bipy and related systems are more stable. Concentration-dependent chemical shifts are observed for the ortho and meta protons of 1,5-dihydroxynaphthalene, indicating host-guest interactions and inclusion phenomena. X-ray crystal structures are reported for the molecular square [(dppp)Pt(bipy)](8+)(4)8(-)OSO(2)CF(3) (15a), as well as a dinuclear dicyanobenzene complex 25 and the [(dppp)M(pyrazine)](2+)2(-)OSO(2)CF(3) (M = Pt, Pd) complexes 20a,b.