Copper ionization potentials

Knickelbein, M.B. (1992) Electronic shell structure in the ionization potentials of copper clusters. Chemical Physics Letters, 192, 129-134. 

Like copper, silver and gold have a single s electron outside the completed d shell, but in spite of the similarity in electronic structures and ionization potential, the chemistries of Ag, Au, and Cu differ more than might be expected. There are no simple explanations for many of the differences although some of the differences between Ag and Au may be traced to relativistic effects on the 6s electrons of the latter. The covalent radii of the triad follow the trend Cu < Ag Au, i.e., gold has about the same or a slightly smaller covalent radius than silver in comparable compounds, a phenomenon frequently referred to as relativistic contraction (c/. lanthanide contraction). 

Ionization energies have been determined by p.e.s. for compounds in the two series (Me2N)3 Cl PS and (EtO)3 Cl PS (n —0—3), and the first ionization potential has been shown to correlate linearly with AG° values for complex formation with iodine in carbon tetrachloride. Re-examination of the reaction between tetramethyldiphosphine disulphide and hydrated copper(ii) chloride in ethanol shows the formation of a dinuclear copper(i) complex [(Me4P2S2)CuCl]2 as the major product, while its precursor, (Me4P2S2)CuCl2, is obtained in minor amounts. X-Ray structure determinations have been carried out on both compounds. 

Like copper, silver and gold have a single s electron outside a completed d shell, but in spite of the similarity in electronic structures and ionization potentials there are few resemblances between Ag, Au and Cu, and there are no simple explanations for many of the differences. 

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