Pd(II)- and Pt(II)-Linked Tetranuclear Complexes as Assembly Units for Higher Ordered Structures

The formation of ···Pt(II)···Br–Pt(IV)··· mixed-valence complexes was utilized for the assembly of square compounds, [(en)M(4,4′-bpy)]4(NO3)8 (1·(NO3)8; a: M = Pt(II), b: M = Pd(II), 4,4′-bpy = 4,4′-bipyridine), into higher ordered infinite complexes. The reaction of 18+ with cationic Pt(IV) complex, [PtBr2(en)2]2+ (22+), afforded a 1 : 3 complex 1a·(2)314+. Crystallographic analysis of this complex showed that two moieties of 22+ bridged at the cis corner of 1a8+ making a stair-like infinite network, whereas another moiety of 22+ was accommodated in the cavity of 1a8+. On the other hand, complexation of 1b with anionic Pt(IV) complex, PtX62− (32−; a: X = Cl, b: X = Br), afforded a 1 : 4 complex 1·(3)4. UV-vis observations suggested the formation of a linear tube structure, in which each corner of 18+ is bridged by the linear X–Pt–X motif of 32−.