Copper cubane structure

Amino acid is one of the most important biological ligands. Researches on the coordination of metal-amino acid complexes will help us better understand the complicated behavior of the active site in a metal enzyme. Up to now many Ln-amino acid complexes [50] and 1 1 or 1 2 transition metal-amino acid complexes [51] with the structural motifs of mononuclear entity or chain have been synthesized. Recently, a series of polynuclear lanthanide clusters with amino acid as a ligand were reported (most of them display a Ln404-cubane structural motif) [52]. It is also well known that amino acids are useful ligands for the construction of polynuclear copper clusters [53-56], Several studies on polynuclear transition metal clusters with amino acids as ligands, such as [C03] [57,58], [Co2Pt2] [59], [Zn6] [60], and [Fe ] [61] were also reported. 

Figure 6 (a) Structural relationships in (a) copper(I) two-, three- and four-coordinate structures and (b) structural relationships between die closed (A) and open (B) cubane structures... 

The tetrahedral CiuXt is the most common tetranuclear copper(I) species and primarily occurs (Figure 4.4, v) as the cubane structure Cu4X4L4, where X is Cl-, Br- pr I- and L is a... 

In these compounds, an alternative structure to the cubane cluster is found, for example in [Ph3PAgI]4.106 This is the chair or step type of arrangement, illustrated in Figure 2, in which two of the four halogen atoms retain a coordination number of three. This arrangement has also been found in some copper(I) halide complexes with bis(diphenylphosphino)methane.1O7 10S The pyramidal coordination of the halogen atom is similar to that in the cubane structure, although often more distorted. 

Reactions of limited proportions of amine and phosphine Lewis bases with non-molecular copper and silver halides generate crystalline cubanes. Crystallographic determinations of molecular structure have been reported for at least 31 complexes with cf or d10 metal configurations, spanning the following types or homologous series of compounds. Compilations of data occur in references 157, 158 and 167. 

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