CYCLOMETALATED FRAGMENTS AS BUILDING-BLOCKS FOR SELF-ASSEMBLY REACTIONS

Organometallic complexes have not hitherto been employed as building b locks in supramolecular chemistry, but they offer a number of interest ing possibilities. Palladium(II) acetate reacts with derivatives of 1, 3-bis-(benzimidazol-2-yl)-benzene (1) to give Pd(1-H)(OAc) which self- assembles to a molecular tricorn, but which may also undergo a second cyclometallation to give [Pd-2(1-2H)(OAc)(2)]. This species may be cle aved by acid to give [Pd-2(1-2H)X-2] (X=Br, TsO); the latter species r eact with hydroxyacetate to give [Pd-2(1-2H)(HOCH2CO2)(2)](2). The cry stal structure of this compound shows two Pd-2(1-2H) fragments clipped together by four bridging hydroxyacetate ligands. (C) 1997 Elsevier S cience S.A.