Vibrational and nuclear magnetic resonance studies of the formation of alkylmercury(II) halide complex anions

Abstract

Vibrational-spectroscopic measurements show the formation of [HgMeCI,]-from [HgMe(CI)] and "Bun4] CI in benzene, chloroform, dichloromethane, tetrahydrofuran, and acetonitrile but not in methanol or water. Similar formation of complex anions occurs for [HgMe(X)] (X = Br, I, or SCN) and for [HgR(X)] (RX = EtCI, Pr"CI, Bu"C1, EtBr, Pr"Br, Bu"Br, or Etl). The effects of the addition of halide ions on 8(lg9Hg), measured by lH-{lg9Hg} INDOR, and 2J(HgH) have been investigated and compared with the effects of solvents on these parameters. It is suggested that the complexes have an essentially linear RHgX group with the second halide much more weakly attached in the equatorial plane.

Host-guest chemistry of an ion-complexation by macrocyclic multidentate Lewis acids

“…The downfield shifts which result upon complexation of halide ions to host 1 are 130 ppm, 200 ppm and 390 pprn for C1, Br and I ions, respectively. Similar downfield shifts were also observed in RHgX and HgX2 systems, when RHgX2-and HgXy are formed (12). It has been known that 199Hg resonances of organomercurials exhibit large solvent and concentration-dependencies.…”

“…Similarly, 2 is the electrophilic analogue of [9]-crown-3. The synthesis of halide ion compplexes of [ 12]mercuracarborand-4 is significant because it efficiently produces a macrocyclic multidentate Lewis acidic host, 1, in a single step. It is believed that halide ions function as templates which direct the assembly of the host macrocycle, since cyclic timer 2 is formed only in H H…”

“…The [ 121 mercuracarborand-4 , 1, is soluble in most electron-donor solvents and it coordinates with these solvent molecules, thus mitigating its potential usefulness in the homogeneous catalysis of organic reactions. In order to elimilnate this competitive binding of solvent molecules, we have synthesized the octaethyl derivative of [ 12]mercuracarborand-4 (4 1 as shown in Scheme 2. The species 9,12-Et2-1,2-C2Bi@10 can be lithiated easily and the resulting dilithio species reacts with HgI2 to form 4.12Li2 and 44Li in a 2:l ratio.…”

“…Closo-Bir$Ii$-is known to be nucleophilic and to form covalent bonds with Lewis acids such as Ag+, Cu+ and Hg2+ (22). Similarly, we studied the intermolecular interaction of closo-BioHi$-( 6) with [ 12]-mercuracarborand-4 (1) and its octaethyl derivative (4) in organic solvents (acetone, CH2C12 and CH3CN) using llB and 1wHg N M R spectroscopy. The *lB N M R spectrum of 6 in CH2C12 exhibited two doublets at 0.83 and -27.3 ppm with a 1:4 ratio, corresponding to axial boron and equatorial boron atoms, respectively.…”

“…Linear mercuric compounds, with two empty mercury p-orbitals, exhibit Lewis acidity towards a variety of Lewis bases and nucleophiles (1 1). Thus organomercury (11) compounds form anionic complexes with halides or pseudohalides in solution (12). However, no anionic complexes of this type have been previously isolated in the solid state because of their low stability.…”