Copper-thiolate model complexes

The blue copper proteins azurin, plastocyanin, stellacyanin, and umecyanin incorporate Cu bound to a combination of N/thiolate/thioether ligands. An important feature of these metalloenzymes is the facile copper(II)/(I) couple that these species exhibit, which is linked to the highly strained, asymmetric coordination geometry at the metal center. The synthesis of model complexes for these so-called Type 1 copper proteins has been reviewed. ... 

Blue Copper Model Complexes for Cu -thiolate Complexes and Fungal Laccase... 

A considerable number of crystal structures of type I copper sites in proteins are now available, so there may be no particular advantage in the synthetic model approach to prove the coordination structure of type I. Yet, inorganic chemists still have an opportunity to utilize the spectroscopic and structural bases established by model studies to understand the precise electronic structure of type I copper. One should keep in mind that the generally accepted interpretation derived from spectroscopic and theoretical studies on the proteins (47-49) has not been definitely proved experimentally. A systematic comparison of a series of copper(II) thiolate complexes having an unusual distorted coordination structure is required for a conclusive description of the electronic structure of the type I copper. The synthetic approach is ultimately the most adequate way to clarify how the ligand donors and geometry affect the electronic property and function of type I copper as an electron transfer center. 

The two thiolate-bridged nickel-copper complexes in Fig. 6.6 have been prepared by reaction of [N2S2]Ni-type complexes with [Cu(CO)(PhTtBu)], the latter available via the carbonylation of [Cu(MeCN)(PhTt Bu)]. These complexes can be employed as model for the catalytic site of the acetyl coenzyme A synthase.14... 

Figure 7 Proposed cluster structures in yeast copper metalloregulatory proteins, (a) [Cu4(SPh)6] model compound. The phenyl rings have been omitted for clarity. Six thiolates bridge the four Cu ions. The sites in Acel and Amtl might resemble this complex, (b) Alternative structure for Acel and Amtl cluster involving eight rather than six cysteines. In this arrangement, only four thiolates are bridging, (c) Proposed structure of...

The copper(II) complexes of 1-thio-a- and -i8-D-glucopyranose and 2-amino-2-deoxy-l-thio- -D-glucopyranose and their peracetates have been synthesised by action of copper(II) acetate on the respective sodium thiolates, followed by acid catalysed acetylation, for an investigation of their anti-inflammatory activity The mesogenic properties of the C4 - dialkyl dithioacetals of ten standard pentoses and hexoses have been examined. Most of them form thermotropic liquid crystals with the notable exception of all L-rhamnose derivatives. A model has been proposed to correlate carbohydrate configuration and melting behaviour. Despite the intrinsic chirality of all carbohydrate mesogens no evidence for chiral mesophases was detected. 

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