Copper tetramers

The pentafluorophenylcopper tetramer is usually analytically pure as isolated and melts at 200° with decomposition. If any significant decomposition occurs during the final drying, the product can be purified by dissolution in ether, filtration to remove copper metal, and precipitation by addition of hexane. It can also be recrystallized from benzene. When kept in a sealed container under nitrogen at room temperature, pentafluorophenyl copper tetramer appears to be stable for reasonable periods. It can be stored indefinitely at -78° under an atmosphere of carbon dioxide. 

Copper Complexes. The preparation of copper and nickel complexes of tridentate metallizable azo and azomethine dyes is easily carried out in aqueous media with copper and nickel salts at pH 4-7 in the presence of buffering agents such as sodium acetate or amines. Sparingly water soluble precursors can be metallized in alkaline medium at up to pH 10 by using an alkali-soluble copper tetram(m)ine solution as coppering reagent, which is available by treating copper sulfate or chloride with an excess of ammonia or alkanolamines [3],... 

The precipitate is soluble in ammonia solution, when dark-blue copper tetram-mine ions are formed ... 

Organocopper compounds can form mixed aggregates. For example, a mixture of pentafluorophenylcopper and o-(trifluoromethyl)phenyl-copper tetramers forms mixed cluster compounds in which ligands have been exchanged. The products may be explained by either a cluster... 

For example, the 2-dimethylaminomethyl-5-methylphenyl copper tetramer [CuC6H3(2-CH2NMe2)(5-Me)]4 contains p2-ligands of the type shown in structure 45a and a butterfly-shaped arrangement of its four metal atoms, whereas the ps-ligand environment is found in 2-dimethylaminophenyl copper compounds 45b. In both types of compounds, pairs of copper atoms are bridged by (hypercoordinate) carbon atoms of the type already noted in Al2Me4Ph2... 

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... 

Figure 47 (a) Chains of copper tetramers in the low-temperature structure [55] (left) and high-temperature stracture [55 ] (right), (b) Copper tetramers in the low-temperature (left) and high-temperature (right) structures. (Reprinted with permission from Ref 73. Copyright (2010) American Chemical Society.)... 

---