Homo- and Heterotrinuclear cyclic complexes of the 11th group metal ions: fifteen years of a golden chemistry

Homo- and Heterotrinuclear cyclic complexes of the 11th group metal ions: fifteen years of a golden chemistry Alfredo Burini1, Vladimir Nesterov2, Mohammad A. Omary2, Oumarou Camille Simon1, Rossana Galassi1 1School of Science and Technology - Chemistry Division, Camerino University, via S. Agostino 1, 62032 Camerino, Italy, e-mail:rossana.galassi@unicam.it 2 University of North Texas, Department of Chemistry, TX 76203, Denton, USA In the last fifteen years our group has given an important contribution to the development of the synthesis of cyclic trinuclear complexes (CTC) of the 11th group metal ions. Our pioneering studies showed that trinuclear cyclic gold(I) complexes with bridging imidazolate or carbeniate ligands can act as π-Lewis base. The interaction of these substrates with metal ions, organometallic compounds or organic molecules showing some Lewis acidity, yield polymeric supramolecular structures showing amazing photoemissive properties. [1] [2] The CTCs can also act as π-Lewis acids: this inversion of the acid/base properties depends on both the ligand and the metal present in the complex; in fact, by using a pyrazolate ligand bearing withdrawing groups (such as NO2), and silver(I) ions as connecting metal, we obtained a silver CTC that interact with small molecules having donor atoms in their structure such as acetone, acetonitrile, pyridine etc.. and it stacks with naphtalene [3] Moreover, some years ago we found a synthetic route to obtain the first heteronuclear CTCs. By using different stoichiometry, Au2I/AgI and AuI/Ag2I CTCs were isolated and structurally characterized. [4] This strategy was applied to yield new heteronuclear AuI/CuI CTCs. The crystal structure of [Au2(μ-C2,N3-BzIm)2Cu(µ-3,5-(CF3)2Pz)], and of [Au2(μ-C2,N3-MeIm)2Cu(µ-3,5-(CF3)2Pz)] are reported and the crystal packing indicates the formation of a dimer of heterobimetallic trimers linked by quite long Au-Cu metallophilic bonds with distances of 3.317 Å (Au2···Cu1B) and 3.232 Å (Au2···Cu1B), respectively. In this case, on the contrary of what already observed in the case of Ag/Au heterobimetallic complexes, the exchange of ligands occurs too. Their formation passes through a likely  -  acid base interaction, affording to stable stacking products only in the case of {Au(μ-C2,N3-BzIm)}3{Cu(µ-3,5-(CF3)2Pz)}3. These complexes exhibit fascinating and sophisticated photophysical properties that are dependent on the excitation wavelength and on the temperature. Leave one line blank [1] A. Burini et al., Inorg. Chem. 39 (2000) p. 3158-3165. [2] A. Burini et al., J. Am. Chem. Soc., 122 (2000) p.11264-11265. [3] R. Galassi et al., Inorg. Chem., 52 (2013) pp 14124–14137. [4] A. Burini et al., Inorg. Chem., 45 (2006) pp 7770-7776.