SYNTHESIS AND MULTINUCLEAR (C-13, SE-77, TE-125, HG-199) MAGNETIC-RESONANCE SPECTRA OF ADAMANTANE-LIKE ANIONS OF MERCURY(II), [(MU-ER)6(HGX)4]2- (E = S, SE, TE, X = CL, BR, I)

Multinuclear magnetic resonance has been used to characterize the new adamantane-like anions [(μ-ER)6(HgX)4]2- (ER = SPrn, SPh, SePh, TePh; X = Cl, Br, I), which are formed in CH2Cl2 and (or) DMF from Hg(ER)2, HgX2 and (R4N)X in the correct stoichiometric ratio. The products (Et4N)2[(μ-EPh)6(HgCl)4] (E = Se, Te) have been isolated analytically pure. At ambient probe temperature, only the complexes [(μ-TePh)6(HgX)4]2- are stable to dissociation of the (μ-ER)6Hg4 core. However, at 213 K, only the core of [(μ-SPh)6(HgCl)4]2- is measurably dissociated. Overall, the stability of the complexes to dissociation varies with E in the order Te > Se > S. At reduced temperature inversion at Te is slow on the NMR time scale in [(μ-TePh)6(HgX)4]2-, and these complexes are shown to exist as one predominant configurational isomer or an equilibrium mixture of, probably, two such isomers. Similar behavior is found for [(μ-SePh)6(HgX)4]2- (X = Cl, Br), which are the first examples of SeR-bridged adamantanoid clusters to exhibit inversion at Se that is slow on the NMR time scale. In [(μ-SePh)6(HgX)4]2-, the inversion rate at Se varies with X in the order I > Br > Cl. Pure (Et4N)2[(μ-SPrn)6(CdI)4] has been synthesized from Cd(SPrn)2, CdI2, and (Et4N)I in a 3:1:2 ratio and fully characterized by NMR spectroscopy. Metal (113Cd, 199Hg) NMR data for [(μ-SPrn)6- (MI)4]2-/[(μ-SPrn)6(M′I)4]2- (M = Hg, M′ = Cd, Zn; M = Zn, M′ = Cd) mixtures at 213 K show that an approximately statistical metal redistribution occurs to give [(μ-SPrn)6(MI)4-n,(M′I)n]2-. © 1990, American Chemical Society. All rights reserved.