Dinuclear copper(i) complexes with N-heterocyclic thione and selone ligands: synthesis, characterization, and electrochemical studies

Abstract

The synthesis, characterization, and structures of a series of homoleptic and heteroleptic copper(I) complexes supported by N-heterocyclic chalcogenone ligands is reported herein. The quasi-reversible Cu(II/I) reduction potentials of these copper complexes with monodentate (dmit or dmise) and/or bidentate (Bmm(Me), Bsem(Me), Bme(Me), Bsee(Me)) chalcogenone ligands are highly dependent upon the nature and number of the donor groups and can be tuned over a 470 mV range (-369 to 102 mV). Copper-selone complexes have more negative Cu(II/I) reduction potentials relative to their thione analogs by an average of 137 mV, and increasing the number of methylene units linking the heterocyclic rings in the bidentate ligands results in more negative reduction potentials for their copper complexes. This ability to tune the copper reduction potentials over a wide range has potential applications in synthetic and industrial catalysis as well as the understanding of important biological processes such as electron transfer in blue copper proteins and respiration.

Directed Design of a AuI Complex with a Reduced Mesoionic Carbene Radical Ligand: Insights from 1,2,3‐Triazolylidene Selenium Adducts and Extensive Electrochemical Investigations

“…The peak potential of the first oxidation at a scan rate of 0.1 V s −1 is found between −0.1 V and 0.4 V. The oxidation seems to proceed as an EC mechanism with a re‐reduction of the formed species, which is found at more negative potential than the expected re‐reduction of the oxidized selone. Similar observations have been previously made for NHC thiones and selones [7] . Most likely, dimerization of the selenium adducts occurs (Scheme 1), which has been proposed [8] and observed before for NHC sulfur adducts, [9] and during electrochemical synthesis of disulfides [10] .…”

Coinage metal complexes of selenoureas derived from N-heterocyclic carbenes

“…28 Dimeric copper complexes, with one or two bridging selenourea ligands, have also been disclosed. 29 However, in the majority of these examples, the N-substituents are rather small primary alkyl groups. A search of the Cambridge Structural Database (CSD; March 2018) reveals few examples with bulkier selenoureas:…”

Diverse silver(i) coordination chemistry with cyclic selenourea ligands

“…and the thallium complex [(2-L)Tl]2 (L = N,N-diethyl-N′-benzoylselenoureato),44 both of which have been crystallographically characterized. The only similar coinage metal analogues are several dicationic copper(I) complexes of dmise and bis(methylimidazole selone)methane 45. Thus, the complexes [1]NO3 and [1]OTf represent the first crystallographically characterized selenourea-group 11 complexes of this type.…”