The TpZn–OH/CS2 reaction: theoretical and preparative visualization of an essential bioinorganic reaction path

Zinc Thiolate Complexes [ZnLn(SR)]+ with Azamacrocyclic Ligands: Synthesis and Structural Properties

“…[26] Quantum mechanical calculations have revealed that a zinc hydrosulfide moiety His 3 Zn-SH is formed in the course of this interconversion. [27] A suitable structural model − the neutral hydrosulfide complex Tp Ph,Me ZnSH − has been found by Vahrenkamp et al [28,29] Our efforts to obtain an equivalent zinc hydrosulfide complex with an azamacrocyclic ligand were not successful because these compounds are not stable. Nevertheless, due to their positive overall charge, our thiolate complexes also could be regarded as suitable model systems for this species.…”

Zinc Thiolate Complexes [ZnLn(SR)]+ with Azamacrocyclic Ligands, Part II: Mechanism of the Reaction with CS2

“…While the thiolate complexes 1 and 2 do not have any spectral intensity in the range 230-240 ppm, the 13 C NMR spectra of the insertion products show strong signals in this spectral region. These lines show the formation of a thiocarbonyl group and thus corroborate the proposed structure of the trithiocarbonate moiety.…”

“…In these solutions, complexes 1a and 2a exist in a dynamic equilibrium with 1 and 2, respectively (see Scheme 4). This causes all carbon atoms, particularly the trithiocarbonate carbons, to exhibit an increased line width in the 13 C spectra. Thus, their detection requires a large number of scans (Ͼ10.000) in order to reduce the signal-to-noise ratio.…”

“…Furthermore, it is worth noting that small changes of the macrocyclic ligand can have a dramatic effect on the reactivity of the thiolate, even though the structural parameters of the substrates and the products are nearly identical. The 13 C NMR spectrum of 1a shows 12 methylene signals. This indicates that the molecule has an asymmetric structure in a chloroform solution.…”

“…[8] This process is performed by many organisms, such as higher plants, [9] algae, [10] lichens, [11] and even by components of the soil. [12] This interconversion has been reproduced experimentally by reacting an established CA model, [Tp Ph,Me ZnOH], with COS. [13] In the course of the reaction, CO 2 is released and the sulfur-analog complex Tp Ph,Me ZnSH is obtained. In addition, this complex is also formed by reacting Tp Ph,Me ZnOH with CS 2 .…”