Tri- and Tetranuclear Metal-String Complexes with Metallophilic d10 -d10 Interactions.

Marian Olaru,Jens Beckmann,Hiroshi Nishihara,Risa Aoki,Julius F Kögel,Stefan Mebs,Matthias Vogt,Ryota Sakamoto,Enno Lork

doi:10.1002/chem.201904106

Marian Olaru, Jens Beckmann + Show 7 more

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https://doi.org/10.1002/chem.201904106

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Abstract

The reaction of 2,6‐F2C6H3SiMe3 with Ph2PLi provided 2,6‐(Ph2P)2C6H3SiMe3 (1), which can be regarded as precursor for the novel anionic tridentate ligand [2,6‐(Ph2P)2C6H3]− (PCP)−. The reaction of 1 with [AuCl(tht)] (tht=tetrahydrothiophene) afforded 2,6‐(Ph2PAuCl)2C6H3SiMe3 (2). The subsequent reaction of 2 with CsF proceeded with elimination of Me3SiF and yielded the neutral tetranuclear complex linear‐[Au4Cl2(PCP)2] (3) comprising a string‐like arrangement of four Au atoms. Upon chloride abstraction from 3 with NaBArF 4 (ArF=3,5‐(CF3)2C6H3) in the presence of tht, the formation of the dicationic tetranuclear complex linear‐[Au4(PCP)2(tht)2](BArF 4)2 (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‐[Au4(PCP)2(tht)2](BArF 4) (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 HgCl2 yielded the neutral trinuclear bimetallic complex [HgAu2Cl3(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 HgII and the anionic tridentate ligand [2,6‐(Ph2PAuCl)2C6H3]− (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.

Highlights

Metallophilic interactions are structurally directing, attractive forces between two or more closed-shell metal ions that prefer [b] R
Heating a mixture of 1, [Au(tht)Cl], and anhydrous CsF as a suspension in THF/CH3CN (1:1) at 60 8C proceeded with elimination of Me3SiF and gave rise to the formation of the neutral tetranuclear complex linear-[Au4Cl2(PCP)2] (3, PCP = 2,6(Ph2P)2C6H3) that was obtained as yellow prisms in 60 % yield after recrystallisation from CH2Cl2/n-hexane (Scheme 2)
When the reaction mixture was subsequently exposed to UV light, an rearrangement and quantitative formation of the dicationic tetranuclear complex cyclo-[Au4(PCP)2(tht)2](BArF4) (5) was observed

Summary

Introduction

Since the first publication on a photoluminescent gold complex by the group of Dori in 1970,[7] numerous examples of photoluminescence based on aurophilic interactions have been reported.[8] Given that bond energies associated with metallophilic interactions rarely exceed 50 kJ molÀl, multidentate substituents or ligands often play a critical role to support multinuclear complexes in which the metal atoms are fixed in close proximity to each other. In this regard, the 2-diphenylphosphinophenyl ligand (I) and derivatives thereof have been frequently used to prepare a. The 2,6-bis(diphenylphosphino)phenyl ligand II is closely related to the diphosphanyl NHC ligand IV and related ligand systems, which were introduced recently (Scheme 1) and were shown to stabilize poly-homo and heterometallic complexes showing metallophilic interactions.[12]

Results and Discussion

Summary and Conclusions

Conflict of interest