Route to Cluster Helicates

Abstract

Most supramolecular helicates contain either two or three metal centers, whereas those with four or more remain relatively uncommon. [1, 2] Strategies for the construction of metallohelicates with high nuclearity use long organic ligand strands or guest molecules as templating agents, and thus some linear [3] and circular helicates [4]

Metal‐Catalysed Oxidation Processes in Thiosemicarbazones: New Complexes with the Ligand N‐{2‐([4‐N‐Ethylthiosemicarbazone]methyl)phenyl}‐p‐toluenesulfonamide

“…In previous work, we have employed Schiff-base ligands derived from thiosemicarbazones [10,11] or containing tosyl groups [9] as useful building blocks for the construction of polynuclear helicates. As a result of our interest in the design of organic systems suitable for the assembly of supramolecular compounds, we decided to incorporate these two molecular motifs in the same ligand to afford combined thiosemicarbazone and tosylamide skeletons.…”

Conversion of a double-tetranuclear cluster silver helicate into a dihelicate via a rare desulfurization process

“…4 In 2005, our group presented for the first time a new class of helicates, the cluster helicates. 5 These cluster helicates combine the inherent properties of metal clusters with the singular arrangement of metallohelicates. Our route to cluster helicates demonstrated that the use of pentadentate or tetradentate thiosemicarbazone ligands in combination with monovalent metal ions led to stable tetranuclear or hexanuclear cluster helicates.…”

Polymerizing Cluster Helicates into High‐Connectivity Networks

“…In the sporadically documented examples of multimetallic helicates with polyhedral central cores,6 few of them displayed significant metal–metal interactions and failed to exemplify genuine cluster helicates. In contrast with the strategy of judicious selection of dianionic helicand ligands,5, 6c an anionic pyrazolate derivate with a typical edge‐bridging mode7 was shown to give an intriguing example of a pentanuclear M 5 L 6 cluster helicate 8. Recently, we utilized a similar cluster helicate ( A ; Figure 1, left) as a template to fabricate helical coordination polymers through a sulfur transformation reaction, and successfully implemented supramolecular helix‐to‐helix induction 9…”

“…A rational consideration indicated that the 4‐pyridyl substituents might serve as bridging spacers for constructing extended architectures in place of the terminal chelating groups (2‐pyridyl substituents) in A (Figure 1, left). Assuming that the configuration of the M 5 L 6 central core remains unchanged by taking advantage of the edge‐bridging mode of the pyrazolate groups, and the 4‐pyridyl substituents stay uncoordinated, it is apparent that an M I metal ion with a low coordination number, other than the M II (e.g., Ni II and Zn II ) metal ions used in the preparation of A , would be required to fulfill the coordination balance between the metal atoms and ligands 5. By taking the above into consideration, we report herein a new M 5 L 6 cluster helicate ( B ; Figure 1, right), which acts as a secondary building unit (SBU) that has 4‐pyridyl vacant sites for further coordination to construct high‐connectivity coordination networks 12…”