Coordination Chemistry of Mercury-Containing Anticrowns. Complexation of Perfluoro-o,o′-biphenylenemercury with o-Xylene and Acetonitrile and the First X-ray Diffraction Evidence for Its Trimeric Structure

Abstract

The paper reports the first X-ray diffraction data evidencing the cyclic trimeric structure of the earlier synthesized octafluoro-o,o′-biphenylenemercury (8), being of considerable interest as a potential anticrown. The conclusion on the trimeric (o,o′-C 6 F 4 C 6 F 4 Hg) 3 structure of this mercuracycle is based on an X-ray structural analysis of its o-xylene and acetonitrile complexes {[(o,o′-C 6 F 4 C 6 F 4 Hg) 3 ](o-Me 2 C 6 H 4 ) 2 } (9) and {[(o,o′-C 6 F 4 C 6 F 4 Hg) 3 ](MeCN) 3 } (10), which were obtained from 8 in an analytically pure state and fully characterized. Complex 9 contains two o-xylene species per one molecule of 8 and forms in the crystal infinite chains consisting of alternating mercuramacrocycle units and bridging o-xylene ligands. One more o-xylene molecule in each macrocyclic fragment of the chain serves as a terminal ligand. Both bridging and terminal molecules of o-xylene are coordinated in all cases with only one Hg site of the corresponding mercuracycle. The back transformation of complex 9 into 8 and o-xylene occurs on its heating in a vacuum at 100−120°C for 2 h. In contrast to 9, complex 10, containing three acetonitrile ligands per one molecule of 8, has a discrete structure in the crystal. In this complex, two of three acetonitrile species are bonded to one and the same Hg center of 8, whereas the third MeCN species is coordinated with the other Hg atom of the mercuramacrocycle.

Anionic Complexes of the Perfluorinated Three‐Mercury Anticrown (o,o’‐C6F4C6F4Hg)3. Dependence of the Anion Coordination Type on Counter‐Cation in Case of Chloride and Bromide Anions

“…[43] Macrocycle 1 in complexes 12 and 13 has a similar structure while somewhat differs from the structure of non-bonded with anions 1. [26] It adopts a bowl shape (the distances between centroids of the phenylene C 6 rings from the anion side are 6.92 and 6.91 Å and from the other side are 5.74 and 5.73 Å for 12 and 13 respectively). Mercury atoms in each of these complexes form equilateral triangles with sides Hg…Hg 3.745(3) Å in 12 and 3.774(1) Å in 13.…”

“…The analogous bromide adduct, [Ph 4 P]{[( o,o′‐ C 6 F 4 C 6 F 4 Hg) 3 ]Br} ( 11 ), was isolated in 72 % yield from the ethanol solution under similar conditions. In the room temperature 199 Hg NMR spectra of the complexes 10 and 11 in acetone‐D 6 ([ 10 ] 0 =[ 11 ] 0 =5×10 −2 M) broadened mercury resonance signals downfield shifted by 65 ppm for 10 and by 87 ppm for 11 with respect to the corresponding signal of neat 1 (δ=−22 ppm relative to external Ph 2 Hg in Py) [26] are observed.…”

“…In none of these adducts Lewis basic ligand is cooperatively coordinated to all Lewis acidic centres of the mercuracycle (i. e. 1 does not behaved as an anticrown). [26] In the present article, the first data on the synthesis and Xray structures of the halide complexes of 1 revealing its…”

“…We have previously reported on the synthesis, spectroscopic characteristics and X‐ray diffraction studies of the o ‐xylene and acetonitrile complexes of 1 . In none of these adducts Lewis basic ligand is cooperatively coordinated to all Lewis acidic centres of the mercuracycle (i. e. 1 does not behaved as an anticrown) [26] …”

Coordination Chemistry of Anticrowns. Synthesis and Structures of Complexes of the Perfluorinated Three‐Mercury Anticrown (o‐C6F4Hg)3 with Monohalogenobenzenes

“…In the last decades, there has been considerable interest in the binding and catalytic properties of macrocyclic multidentate Lewis acids representing antipodes of conventional crown compounds and called anticrowns (see reviews and papers cited in refs). These remarkable reagents exhibit a high affinity toward various anions and neutral Lewis bases forming complexes with them wherein the Lewis basic species is cooperatively coordinated by all Lewis acidic centers of the anticrown.…”