Supramolecular assembly and structural transformation of d¹⁰-metal complexes containing...

The reaction of potassium (aza-15-crown-5)dithiocarbamate (KO₄NCS₂) and (Me₂S)AuCl gave the dinuclear complex [Au(O₄NCS₂)]₂, which underwent structural transformation upon heating to rearrange into the hexanuclear complex [Au(O₄NCS₂)]₆. Under similar reaction conditions, KO₄NCS₂ reacted with AgNO₃ or [Cu(CH₃CN)₄]ClO₄ to give the 1-D coordination polymer [Ag(O₄NCS₂)] (1) and the tetranuclear complex [Cu(O₄NCS₂)]₄ (2), respectively. It is noted that upon heating a similar structural transformation process occurs from tetranuclear complex 2 to the octanuclear complex [Cu(O₄NCS₂)]₈ (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 MO₄NCS₂ salts (M = Li⁺, Na⁺, K⁺ and Rb⁺) were used to react with AgNO₃ to construct a series of coordination architectures: [LiAg(O₄NCS₂)₂(μ-H₂O)_0.5]₂ (3), {Na[Ag(O₄NCS₂)₂]} (4), {K[Ag(O₄NCS₂)₂]} (5) and {Rb[Ag(O₄NCS₂)₂]} (6). The smallest Li⁺ ion only coordinates with four oxygen atoms from the same azacrown ether ring and one H₂O 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 μ₂-bridging ([Au(O₄NCS₂)]₂ and [Au(O₄NCS₂)]₆), μ₃- and μ₄-bridging (1-2) and chelate forms (3-6) in the structural backbones.