Polynuclear anion-bridged complexes

Polynuclear anion-bridged complexes. The complex cations [(NHjl CoCp-NH2)(p-RC02)Co(NH3)4] (R = H or Me) have been prepared from the corresponding p-amido-p-chloro-dimer. The dinuclear cation (109) and its deprotonated analogue have been isolated, as have the related cations [(NH,) - 

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In the case of the sulfate anion SO, complexes are described in which the ligand performs a terminal (104) or chelating (105) function in mononuclear compounds, but the same ligand behaves as a bridge ligand system (106) in di- and polynuclear structures [(3,13,128-131] ... 

Nevertheless at the Cu(II) state, in the presence of base, deprotonation of the exo-bound water molecule occurs and leads to the formation of polynuclear hydroxo bridged species (Figure 7). This results from the combined effect of host flexibility, basicity of the exo site, and reluctance of the complex to bind anions in endo position (see below). 

At higher temperatures the monomer is the predominant species although the rate of hydrolysis to U03 is increased. U03 dissolves in uranyl solutions to give U02OH+ and polymerised hydroxo-bridged species. Polynuclear species could arise from U4+ as it hydrolyses in dilute acid solutions. Complex ions are formed with thiocyanate, phosphate, citrate and anions of other organic acids. 

By the stepwise thermal decomposition of the tris chelate, mono adducts of the type [NiX2(N—N)] (X = halides, NCS) were obtained.852-854 These complexes are polynuclear six-coordinate with bridging anions. In the thiocyanato derivative the nickel atoms are ferromagnetically coupled. 

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