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respectively. All P-Au vectors point approximately to the center of the cluster with normal P-Au distances (2.27 ± 0.09 A). Physical data including 197Au Mossbauer and (solid-state) 31Pj'H) NMR are reported. [Au7L7]+ can also be observed during the reaction of L with the novel compound [AugL6I]PF6. The latter cluster could be prepared from the reaction of [Au9Lg]3+ with Bu4NI. The intermediacy of the title compounds in the formation and reactivity of gold cluster compounds will be discussed.Synthesis, Structure, and Magnetic Properties of Fluoride-Bridged Copper(II) Dimers. Crystal and Molecular Structures of Bis(^-fluoro)bis[tris(3,4,5-trimethylpyrazole-iV1 2)copper(II)] Bis (tetrafluoroborate) and Bis(^-fluoro)bis[(5-methylpyrazole-JV2)bis(3,5-dimethylpyrazole-Ar2)copper(II)] Bis (tetrafluoroborate)

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Received December 29, 1994®The copper complexes of bis [2-(3,5-dimethyl-l-pyrazolyl)ethyl]amine (1) and its benzylated derivative (2) have been studied as single crystals by X-ray crystallography and as powders and solutions by a variety of techniques.[Cu(l)*2 N Û 3] (C 14H 25CUN7O 7 including 1 H 2O, 3) crystallized in the monoclinic space group Pc (No. 7) with a bis(pyrazole) complexes, in particular for complex 6 , are explained by the fact that the Cu(II) complexes have the correct ligand geometry for the stabilization of Cu(I). duction e elucidation of the mechanisms2-4 by which the dicopper loprotein hemocyanin5 binds dioxygen continues to be a c of great interest.6-8 Model compounds mimicking the n of hemocyanin and related metalloproteins have been ed and synthesized by several groups.9-11 Karlin and orkers have shown that Cu(I) bis(pyridine) complexes are tive dioxygen binders.12,13 Sorrell and co-workers on the uthor to whom correspondence should be addressed, sent address: Department of Chemistry. other hand have presented evidence that the related copper(I) bis(pyrazole) complexes do not bind dioxygen. 14 More detailed insight in the factors regulating the properties of these types of complexes is therefore required.Recently, we reported on the reduction of Cu(II) bis(pyrazole) crown ether complexes in alcoholic solutions.I:> The observed rapid reduction of the Cu(II) complexes, and the remarkable stability of the Cu(I) species, even in the presence of dioxygen, prompted us to investigate this system in detail. In particular we were interested to elucidate the factors that control the geometry, electrochemical behavior, and reactivity of our Cu-(II) bis(pyrazole) complexes.Central in this study are the ligands bis[2-(3,5-dimethyl-lpyrazolyl)ethyl]amine (1) and the benzylated derivative 2 (Chart 1). These two ligands are treated with Cu(N0 3 )2*3 H2 0 and Cu-(10) Kitajima, N.; Fujisawa, K