Supramolecular assembly and structural transformation of d-metal complexes containing (aza-15-crown-5)dithiocarbamate.

The reaction of potassium (aza-15-crown-5)dithiocarbamate (KONCS) and (MeS)AuCl gave the dinuclear complex [Au(ONCS)], which underwent structural transformation upon heating to rearrange into the hexanuclear complex [Au(ONCS)]. Under similar reaction conditions, KONCS reacted with AgNO or [Cu(CHCN)]ClO to give the 1-D coordination polymer [Ag(ONCS)] (1) and the tetranuclear complex [Cu(ONCS)] (2), respectively. It is noted that upon heating a similar structural transformation process occurs from tetranuclear complex 2 to the octanuclear complex [Cu(ONCS)] (2'), connected by a weak Cu⋯S contact of 2.846 Å, and it has been isolated and corroborated by powder and single-crystal X-ray diffraction studies as well. Moreover, a variety of MONCS salts (M = Li, Na, K and Rb) were used to react with AgNO to construct a series of coordination architectures: [LiAg(ONCS)(μ-HO)] (3), {Na[Ag(ONCS)]} (4), {K[Ag(ONCS)]} (5) and {Rb[Ag(ONCS)]} (6). The smallest Li ion only coordinates with four oxygen atoms from the same azacrown ether ring and one HO molecule, leading to a 1-D hydrogen-bonded chain with another azacrown ether ring for complex 3. The larger Na ion coordinates with seven oxygen atoms from two different crown ether rings, leading to a 1-D chain for complex 4. However, the largest K and Rb ions constitute a 1-D framework, except that each metal ion coordinates with eight oxygen atoms from two different crown ether rings, featuring a 1-D helical chain for complexes 5 and 6. Hence, the different sizes of alkaline metal ions exert a dramatic effect on the structural motifs of complexes 3-6. Remarkably, the dithiocarbamate moieties adopt μ-bridging ([Au(ONCS)] and [Au(ONCS)]), μ- and μ-bridging (1-2) and chelate forms (3-6) in the structural backbones.