Metal(II) complexes with monodentate S and N ligands as structural models for zinc–sulfur DNA-binding proteins

Chelation and Bridging of Zinc(II) by Tetradentate N2S2Donor Ligands: Similarities and Differences to Copper(I) and Copper(II) Systems

“…We therefore report here our results from the reactions of zinc triflate with the tetradentate bis(benzimidazole-thioether) ligands bmbdh = 1,6-bis(N-methylbenzimidazol-2-yl)-2,5-dithiahexane and bmdhp = 1,7-bis(N-methylbenzimidazol-2-yl)-2,6-dithiaheptane (see [3,5] or their models [4,6,7].…”

“…The weak bonding of the thioether donors at about 2.6 Å Zn-S distance allows for enough space to adopt additional O donors which is less likely when strongly coordinated thiolate ligands such as in zinc finger configurations and their models are present (d Zn-S ca. 2.3 Å [4][5][6][7]). Then, the tetracoordinate arrangement is the alternative which may also offer a greater degree of structural (angular) flexibility than the hexacoordinate situation.…”

“…The N 2 S 2 ligation of the zinc ion has received much attention [4][5][6][7] since zinc finger proteins were discovered to contain modular motifs ("fingers") involving two neutral histidine-N and two anionic cysteinato-S donor atoms coordinated to Zn 2+ [1][2][3]5] These zinc fingers ( Figure 1) act as structure-maintaining entities for specific protein-nucleic acid recognition in the transcription process [3,5]. In connection with modelling the zinc finger coordination there have been previous synthetic and structural reports on complexes with bis(thiolato)-bis(imidazole) [6] or -bis(benzimidazole) [7] and bis(thioether)-bis(pyridyl) or -bis(amine) coordinated zinc, with and without additional O donor ligation [8].…”

Thermodynamic Stability Versus Kinetic Lability of ZnS4 Core

“…Steric bulk is clearly important in these cases, but it is noteworthy that the zinc coordination sphere can be completed by a smaller fourth ligand, such as 1methylimidazole. [49] Third, few mononuclear complexes having a [ZnS 4 ] 2À core have been structurally characterized [28] and almost all of these are zinc tetraarylthiolates; [51][52][53][54] zinc tetraalkylthiolates have only been obtained with bidentate ligands [55] or within peptide frameworks. [10,12,[56][57][58] Fourth, total Zn À S binding energies are calculated to be higher in three-coordinated than four-coordinated zinc-thiolates.…”

A new type of metal-binding site in cobalt- and zinc-containing adenylate kinases isolated from sulfate-reducers Desulfovibrio gigas and Desulfovibrio desulfuricans ATCC 27774

“…A search of the Cambridge Crystallographic Data Base for both zinc and cobalt species having 4 and 5 coordination, and mixed sulphur and nitrogen or oxygen donors indicated a closest match of our EXAFS determined bondlengths (Table 2) with four coordinate sites with either NS 3 or N 2 S 2 coordination, with slightly better overall agreement for NS 3 coordination. For both zinc and cobalt structurally characterized low-molecular weight species exists with three thiolates and one imidazole ligand [54][55][56]. The Zn compounds have average values for Zn-S and Zn-N bond-lengths of 2.32 and 2.07 Å , respectively, while the Co compound has Co-S and Co-N bond-lengths of 2.30 and 2.07 Å , respectively, all of which are in good agreement with the values determined from the EXAFS curve fitting ( Table 2).…”