Tri- and Tetranuclear Metal-String Complexes with Metallophilic d -d Interactions.

The reaction of 2,6-F C H SiMe with Ph PLi provided 2,6-(Ph P) C H SiMe (1), which can be regarded as precursor for the novel anionic tridentate ligand [2,6-(Ph P) C H ] (PCP) . The reaction of 1 with [AuCl(tht)] (tht=tetrahydrothiophene) afforded 2,6-(Ph PAuCl) C H SiMe (2). The subsequent reaction of 2 with CsF proceeded with elimination of Me SiF and yielded the neutral tetranuclear complex linear-[Au Cl (PCP) ] (3) comprising a string-like arrangement of four Au atoms. Upon chloride abstraction from 3 with NaBAr (Ar =3,5-(CF ) C H ) in the presence of tht, the formation of the dicationic tetranuclear complex linear-[Au (PCP) (tht) ](BAr ) (4) was observed, in which the string-like structural motif is retained. Irradiation of 4 with UV light triggered a facile rearrangement in solution giving rise to the dicationic tetranuclear complex cyclo-[Au (PCP) (tht) ](BAr ) (5), which comprises a rhomboidal motif of four Au atoms. In 3-5, the Au atoms are associated by a number of significant aurophilic interactions. The atom-economic and selective reaction of 3 with HgCl yielded the neutral trinuclear bimetallic complex [HgAu Cl (PCP)] (6) comprising significant metallophilic interactions between the Au and Hg atoms. Therefore, 6 may be also regarded as a metallopincer complex [ClHg(AuCAu)] between Hg and the anionic tridentate ligand [2,6-(Ph PAuCl) C H ] (AuCAu) containing a central carbanionic binding site and two "gold-arms" contributing pincer-type chelation trough metallophilic interactions. Compounds 1-6 were characterized experimentally by multinuclear NMR spectroscopy and X-ray crystallography and computationally using a set of real-space bond indicators (RSBIs) derived from electron density (ED) methods including Atoms In Molecules (AIM), the Electron Localizability Indicator (ELI-D) as well as the Non-Covalent Interaction (NCI) Index.