Copper computational studies

Blue copper proteins in their oxidized form contain a Cu2+ ion in the active site. The copper atom has a rather unusual tetra-hedral/trigonal pyramidal coordination formed by two histidine residues, a cysteine and a methionine residue. One of the models of plastocyanin used in our computational studies (160) is pictured in Fig. 7. Among the four proteins, the active sites differ in the distance of the sulfur atoms from the Cu center and the distortion from an approximately trigonal pyramidal to a more tetrahedral structure in the order azurin, plastocyanin, and NiR. This unusual geometrical arrangement of the active site leads to it having a number of novel electronic properties (26). 

The significant experimental effort put into characterizing the blue copper proteins has made them attractive targets for computation (161-163). These computational studies have provided... 

A case of anomalous 1,3-dioxolane formation has been reported when the sesquiterpene lactone parthenin 9 is treated under Baylis-Hillman conditions with aromatic aldehydes and affords products of type 10 <07TL955>. A computational study of copper-catalysed carbonyl... 

A computer study has identified the critical chemical feature required in an AI agent to exploit serum albumin bound copper. Although the mechanism of action of copper complexes is unknown, stimulation of superoxide dismutase has been proposed as a contributing factor. ... 

A computational study of the activation of alkane (methane, ethane, propane, and butane) C-H bonds by silver carbene homoscor-pionate [Ag=C(H)(C02CH3)(Tp)] and [Ag=C(H)(C02CH3)-(TpBr3)], anal0g0us tx> that reported for copper,549 has been performed with DFT Becke3LYP calculations. 

Abstract The transition metal complexes of the non-innocent, electron-rich corrole macrocycle are discussed. A detailed summary of the investigations to determine the physical oxidation states of formally iron(IV) and cobalt(IV) corroles as well as formally copper(III) corroles is presented. Electronic structures and reactivity of other metallocorroles are also discussed, and comparisons between corrole and porphyrin complexes are made where data are available. The growing assortment of second-row corrole complexes is discussed and compared to first-row analogs, and work describing the synthesis and characterization of third-row corroles is summarized. Emphasis is placed on the role of spectroscopic and computational studies in elucidating oxidation states and electronic configurations. 

Tolman and co-workers reported dioxygen activation at a single copper site (Equation 11.53) [116]. The existence of the copper peroxide species was supported by both experimental and computational studies. 

D. Computational Studies on Copper-Zinc SOD Molecular Biology and Chemical Modifications... 

When the prediction or interpretation of spectroscopic properties and reactivities of metalloenzymes is the aim, QM-based methods - and DFT in particular - have proven to be the methods of choice [498]. Some of the recent results in the area of blue-copper proteins have been discussed above, and the methods used to interpret and predict spectroscopic parameters are provided in Chapter 10. Here, we concentrate on computational studies related to the understanding of the reactivity of... 

Subsequent kinetic, spectroscopic, and computational studies, however, support a different mechanistic pathway [28, 29]. A simplified version of the mechanism features oxidation of Cu and TEMPOH by Oj to afford a Cu -OH species and TEMPO (Scheme 6.1). The copper hydroxide and nitroxyl radical... 

Although many aspects of this mechanism have been accepted, computational studies by Nakamura and experimental studies by Bertz and Ogle suggest that modifications to this proposal are needed to fit the current data. Bertz and O e obtained the first spectroscopic data on the allylcopper(III) intermediates fiiat are commonly proposed in copper-catalyzed allylic substitution reactions. Their data imply that the structure of the aUyl dimethylcopper(ni) species contains a ir-allyl unit. 

From biochemical studies of Klinman and co-workers, both enzymes proceed via similar activated intermediates, most recently postulated to be a superoxide-copper(ll) species (4,66). Chen and Solomon s computational studies also invoke a Cu(ll)-(02 ) (possibly with side-on -binding) substrate hydrogen-abstracting active species (67). Their overall mechanisms proposed differ in some details. That proposed by Klinman is given in (Scheme 4) (4,66). Other possible alternative oxidizing intermediates (ie, a Cu(II)-OOH complex or a Cu(H)-(0 ) Cu(III)-(0 )) are still under debate. 

---