The solid state structure of arene-mercury(II) complexes from magic-angle spinning carbon-13 NMR and the solution carbon-13 NMR of some complexes of mercury(II) with arenes having bulky aliphatic substituents

Abstract

The cross-polarization magic angle spinning 13C NMR spectra of Hg(SbF 6) 2 - 2 Arene (Arene = C 6HMe 5, 1,2,4,5-C 6H 2Me 4, 1,2,3,4-C 6H 2Me 4, or C 6H 6) have been measured. The spectra of the complexes of C 6HMe 5 and 1,2,4,5-C 6H 2Me 4 are consistent with static η 1-bonding of the mercury to the arene at an unsubstituted carbon atom, while the spectra of the 1,2,3,4-C 6H 2Me 4 and C 6H 6 complexes show the arene to have time-averaged C s or C 2, and C 6 symmetry respectively, at the temperature of measurement (300 K). The reduced temperature 13C NMR spectra of Hg(Arene) n 2+ ( n = 1 or 2; Arene = 1,3,5-C 6H 3R 3 (R = Me, i-Pr, or t-Bu)) in SO 2 solution are also reported and affirm that in these intramolecularly mobile species the mercury bonds in an η 1-manner, with unsubstituted aryl carbon atoms being the strongly preferred point of mercury attachment. This site preference is further demonstrated by the solution 13C NMR spectra of Hg(Arene) n 2+ (Arene = 1,2,3,4-C 6H 2-Me 4, n = 1 or 2; Arene = 1,4-C 6H 4R 2, R = Me or t-Bu, n = 1). The spectra of the 1,4-C 6H 4R 2 complexes and Hg( p-C 6H 4-t-BuMe) 2+ provide clear evidence for steric influence of the binding site. Like Hg(C 6Me 6) 2 2+, but unlike most of the complexes of substituted benzenes which have been studied, Hg(1,3,5-C 6H 3-i-Pr 3) 2 2+ exchanges only slowly with excess free ligand.