Self-assembly of D-penicillaminato M6M'8 (M = Ni(II), Pd(II), Pt(II); M' = Cu(I), Ag(I)) clusters and their organization into extended La(III)M6M'8 supramolecular structures

A series of chiral M(6)M'(8) cluster compounds having twelve free carboxylate groups, M(6)M'(8)(D-pen-N,S)(12)X](5-) (M/M'/X = Pd(II)/Ag(I)/Cl(-) (1](5-)), Pd(II)/Ag(I)/Br(-) (2](5-)), Pd(II)/Ag(I)/I(-) (3](5-)), Ni(II)/Ag(I)/Cl(-) (4](5-)), Pt(II)/Ag(I)/Cl(-) (5](5-)), Pd(II)/Cu(I)/Cl(-) (6](5-)); D-H(2)pen = D-penicillamine), in which six cis-M(D-pen-N,S)(2)](2-) square-planar units are bound to a M'(8)X](7+) cubic core through sulfur-bridges, was synthesized by the reactions of cis-M(D-pen-N,S)(2)](2-) with M' in water in the presence of halide ions. These M(6)M'(8) clusters readily reacted with La(3+) in aqueous buffer to form La(III)(2)M(6)M'(8) heterotrimetallic compounds, La(2)1](CH(3)COO), La(2)2](CH(3)COO), La(2)3](CH(3)COO), La(2)4](CH(3)COO), La(2)5](CH(3)COO) and La(2)6]Cl, in which the M(6)M'(8) cluster units are linked by La(3+) ions through carboxylate groups in a 1?:?2 ratio. While the La(III)(2)M(6)Ag(I)(8) compounds derived from 1](5-), 2](5-), 3](5-), 4](5-) and 5](5-) have a 1D helix supramolecular structure with a right-handedness, the La(III)(2)Pd(II)(6)Cu(I)(8) compound derived from 6](5-) has a 2D sheet-like structure with a triangular grid of the Pd(II)(6)Cu(I)(8) cluster units. When aqueous HCl was added to the reaction solution of 6](5-) and La(3+), another La(III)(2)Pd(II)(6)Cu(I)(8) heterotrimetallic compound, La(2)6]Cl·HCl, in which the Pd(II)(6)Cu(I)(8) cluster units are linked by La(3+) ions to form a 2D structure with a rectangular grid, was produced. The solid-state structures of these La(III)(2)M(6)M'(8) compounds, determined by single-crystal X-ray crystallography, along with the spectroscopic properties of the M(6)M'(8) cluster compounds in solution, are described.