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Dalton Trans., 2003, 2686 - 2690, DOI: 10.1039/b304023b
Methyl substituted benzene adducts of trimeric perfluoro-o-phenylene mercury
Mason R. Haneline, Julie B. King and François P. Gabbaï
Trimeric perfluoro-ortho-phenylene mercury ( 1) dissolves in substituted benzenes including toluene, ortho-xylene, meta-xylene, para-xylene and is sparingly soluble in mesitylene. The 199Hg NMR resonance of 1 in toluene, ortho-xylene, meta-xylene, and para-xylene appears at
–1051.8, –1053.5, –1051.4 and –1059.1 ppm, respectively. These resonances are slightly upfield from the resonance observed for 1 in CH2Cl2(–1045.2 ppm) and possibly indicates the solvation of the mercury centres by molecules of arenes. Slow evaporation of solutions of 1 in toluene, ortho-xylene, meta-xylene, para-xylene and mesitylene affords 1·toluene ( 2), 1·ortho-xylene ( 3), 1·meta-xylene ( 4), 1·para-xylene ( 5) and 1·mesitylene ( 6), respectively, as crystalline complexes. These adducts have been characterized by elemental analysis and X-ray crystallography. Thermogravimetric analyses indicate that 2–5 begin to lose the coordinated arene at a temperature below 50 °C; however, in the case of 6 loss begins around 91 °C. The structures of 2, 4 and 5 reveals the existence of binary stacks in which the aromatic core of the benzenes approaches the mercury centres of 1. In the case of 3 and 6, the aromatic molecule appears preferentially bound to one of the two proximal molecules of 1. Hence, 3 and 6 are best described as discrete 1 
1 complexes. In 2–6, the resulting Hg
Caromatic distances are in the range 3.2–3.5 
and are within the sum of the van der Waals radii. They reflect the presence of secondary polyhapto 
-interactions occurring between the electron-rich aromatic molecules and the acidic mercury centres.
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