Copper complexes molecular orbital calculations

Molecular orbital calculation by using the DV-Xa method for the tetraaza macnx clic copperfll) conqrlexes were performed with an FACOM-780/10S computer. The reliable crystal parameters of the molecular structures of the copper(II) complexes have not yet been reported. Therefore, their atomic positions of the macrocyclic ligands were estimated fi om similar stmctures in reported analogous complexes. 

The XANES peaks of the tetraazacopper(II) complexes in Fig. 2 are sharper than those of the diazadioxacopper(n) complexes, so that it is convenient to compare the observed spectra with the calculated ones. For these reasons, molecular orbital calculations of the complexes A, B, C, and D were carried out by the DV-Xa method. The atomic positions used on each molecular model of the macrocyclic copper(II) complexes in these calculations are given in Tables. The electron density distribution maps were calculated and are shown in Fig.3. 

In the present study, we synthesized dibromo(l,4,8,ll-tetraazacyclotetradecane)copper(II) ([CuBr2(cyclam)]) and diaqua(l,4,8,ll-tetraazacyclotetradecane)copper(II) difluoride four hydrate ([Cu(cyclam)-(H20)2]F2 4H20) complexes and performed single crystal structure analysis and X-ray absorption near-edge structure (XANES) measurements in crystals and in aqueous solution. Furthermore, DV-Xa molecular orbital calculations have been made for models based on these results, and the structures and electronic states of the [Cu(cyclam)] complexes in crystals and in aqueous solution are discussed, in particular, on the axial coordination to Cu(II). 

Ros, P., Schuit, G. C. A. (1966) Molecular orbital calculations on copper-chloride complexes, Theoret. Chim. Acta 4,1. 

More advanced semiempirical molecular orbital methods have also been used in this respect in modeling, e.g., the structure of a diphosphonium extractant in the gas phase, and then the percentage extraction of zinc ion-pair complexes was correlated with the calculated energy of association of the ion pairs [29]. Semiempirical SCF calculations, used to study structure, conformational changes and hydration of hydroxyoximes as extractants of copper, appeared helpful in interpreting their interfacial activity and the rate of extraction [30]. Similar (PM3, ZINDO) methods were also used to model the structure of some commercial extractants (pyridine dicarboxylates, pyridyloctanoates, jS-diketones, hydroxyoximes), as well as the effects of their hydration and association with modifiers (alcohols, )S-diketones) on their thermodynamic and interfacial activity [31 33]. In addition, the structure of copper complexes with these extractants was calculated [32]. 

The reactivity of palladium and copper cluster models toward diazirine has been compared using the LCGTO-MCP-LSD method <1996SUS11> such calculations were performed to give an insight into the differential bond scission experimentally observed in the thermal decomposition of diazirine on palladium and copper surfaces. Stronger chemisorption was evident with palladium and furthermore, partial diazirine lowest-unoccupied molecular orbital (LUMO) occupation only occurred for the copper cluster model systems. The calculated N-N bond order was significantly decreased in the copper complexes of excited state diazirines, whereas palladium complexes remained unperturbed. 

Recently, we have proposed a methodology [71] similar to the last approach, but using semiempirical molecular orbital methods instead of TDHE methods, to calculate the frequency-dependent polarizability properties of the molecule-surface complex. Although this is a lower level description of the electronic structure, the use of semiempirical methods allows us to describe more complex molecules than has been considered in earlier studies. In the following, we present some recent results for the pyridine-copper tetramer system, and we examine the influence of molecule-metal distance on the Raman intensities for this model. There are two components to the calculation of the Raman intensity (1) calculation of the ground state structure and normal coordinates and (2) calculation of the derivative of the frequency-dependent... 

The complete LFMM force field has been implemented in the molecular operating environment (MOE) as an extension named DommiMOE (d orbital molecular mechanics in MOE) [28]. LFMM has been applied extensively to copper complexes, from simple Cu(II) amines [29] to copper enzymes [32], and a variety of force field parameters for copper complexes are available. The parametrization is done by fitting the parameters in (4) to the crystallographic stracture data provided by the Cambridge Structural Database [29, 30], while DFT calculation results are sometimes also involved in the fitting [32]. 

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