Copper atom configurations

Calculated energy levels for two copper atom configurations... 

An example of metal with significant d-bonding is copper. The atomic configuration of copper is... 

Is 2s 2p 3s 3p 3d 4s. If the 3d states were truly core states, then one might expect copper to resemble potassium as its atomic configuration is ls 2s 2p 3s 3p 4s The strong differences between copper and potassium in temis of their chemical properties suggest that the 3d states interact strongly with the valence electrons. This is reflected in the energy band structure of copper (figure Al.3.27). 

The absolute configuration of the cycloaddition product obtained by the reaction of ketones with activated dienes catalyzed by (S)-t-Bu-BOX-Cu(II) (S)-21b points also to an intermediate in which the geometry around the central copper atom is square-planar similar to 26 above, and that the diene approaches the carbonyl functionality in an endo fashion. 

Apparent anomalies in the filling of electron orbitals in atoms occur in chromium and copper. In these elements an electron expected to fill an s-orbital fills the d-orbitals instead, (a) Explain why these anomalies occurs, (b) Similar anomalies are known to occur in seven other elements. Using Appendix 2C, identify those elements and indicate for which ones the explanation used to rationalize the chromium and copper electron configurations is valid, (c) Explain why there are no elements in which electrons fill ( / + I )s-orbitals instead of np-orbitals. 

The 2 1 species are known as cuprates and are the most common synthetic reagents. Disubstituted Cu(I) species have the 3c 10 electronic configuration and would be expected to have linear geometry. The Cu is a center of high electron density and nucleophilicity, and in solution, lithium dimethylcuprate exists as a dimer [LiCu(CH3)2]2.3 The compound is often represented as four methyl groups attached to a tetrahedral cluster of lithium and copper atoms. However, in the presence of Lil, the compound seems to be a monomer of composition (CH3)2CuLi.4... 

There are several prerequisites which have to be fulfilled for the one electron ECP approach to be applicable. In the case of metal clusters the atomic configuration must be known, i.e. one must safely be able to assume a dns2 or a drL+1s1 configurations on the atoms in the cluster. The d orbitals should not form covalent bonds neither within the cluster nor between the cluster and the adsorbate. Ferromagnetic metals and copper are likely to have these properties. For other metals this is not so clear. Indications are that e.g. the ground state of the Pts cluster is low spin with developed covalent intra cluster d-d bonds[22]. 

Both molecules contain the same donor atom configuration. Diacetyldioxime is highly specific for nickel and palladium. If the same donor atom configuration is incorporated into a heterocyclic system, as in the phenanthrolines, the ligands become specific for copper and iron. This specificity can be directed by choice of the substituents R in the molecule if R = H, the ligand is specific for iron with R = CH3 and/or C 6H5. the ligand is copper-specific. 

A mechanism for carbon-carbon bond formation involving 8 2 displacement at carbon is consistent with the above observations. Two possible pathways for coupling were mentioned 297) (1) a simple displacement of halide by an alkyl group [Eq. (60)], and (2) displacement of the halide by the copper atom s d electrons, with inversion of configuration, to form a copper(III) species which decomposes with retention of... 

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