Chemical aspects of the toxicity of mercury compounds

Chemical aspects of the toxicity of mercury compounds and the use of British anti-Lewisite [BALH₃ , CH₂(SH)CH(SH)CH₂OH] as an antidote for mercury poisoning have been investigated. Assignments of vas(SMS) and vs(SMS) for the complexes M(SR)₂ (M = Zn , Cd , Hg ; R = Et , But) and Hg(SRI)₂ (R' = me , Ph CH₂CH₂0H) are reported. Comparison of frequencies for the complex Hg(SBut)₂ containing four-coordinate mercury with those of Hg(SR")₂ (R" = Me , Et) containing two-coordinate mercury allows assignment of a polymeric structure with linear coordination, (-Hg-S-S-)n (n > 1), rather than the cyclic, monomeric structure usually drawn for the 1 : 1 complex of Hg(II) with BALH₃, Hg(BALH). An analogous derivative of 1,3-dimercapto-2-propanol (DMPH₃),Hg(DMPH), adopts a similar polymeric structure in the solid state and is dimeric in pyridine. Crystalline Hg(DMPH).py1.5, which rapidly loses pyridine at ambient temperature, is obtained from a pyridine solution of Hg(DMPH). The dithiols BALH₃ and DMPH₃ form complexes RHgS-SHgR (R = Me , Ph). Infrared, Raman, and ¹H NMR spectra of RHg(II) and Hg(II) dithiol complexes are compared with those of PhHgSR (R = Me , Et , Pr' , But , Ph , CH₂CH₂0H) and Hg(SR1)₂ (Rs = Me , Et , But , ph , CH₂CH₂0H). Mercury-sulphur stretching frequencies have been assigned for most of these complexes. Phenylmercury(II) , thiolates have the coupling constant J(orthoH-199 Hg) within the range 144-155 Hz. The complexes PhHgSR and Hg(SR")₂ (R" = Et , But , Ph) ere monomeric in chloroform; the chloroform insoluble complexes Hg(SR"')₂ (R'" = Me , CH₂CH₂OH) and organomercury(II) dithiolates (RHg)₂LH (R = Ph , LH = BALH; R = Me , Ph , LH = DMPH) are monomeric in pyridine. The PhHg(II) dithiolate (PhHg)₂DMPH crystallizes as an adduct (PhHg)₂DMPH.py from pyridine. The PhHg(II) dithiolates decompose in benzene and methanol at ambient temperature to form diphenylmercury. The preparation and characterization of Hg(II), PhHg(II) and MeHg(II) complexes of L-cysteine and DL-penicillamine are reported. Infrared and Raman spectra of the new complex p-cysteinato-S,N-bis[phenylmercury(M]monohydrate and of previously reported complexes of L-cysteine and DL-penicillamine are compared. The complexes decompose to form diphenylmercury when stirred as suspensions in benzene at ambient temperature. The complexes RSHgX (R = Me , Et, But ; X = Cl , Br) form non-conducting solutions in pyridine, and either crystallize from pyridine [MeSHgBr and EtSHgX(X = Cl , Br)] or form pyridine mplexes[MeSHgCl.py,(BuSHgC1)₂.py, and Bu SHgBr.py]. An X-ray crystal structure analysis of (ButSHgC1)₂.py has been determined by Drs. A.H. White and C.L. Raston. The structure is based on a zig-zag polymer chain of mercury and sulphur atoms of bridging Bu S groups (-Hg-S-). Every alternate mercury is bonded to chlorine and nitrogen of pyridine to give distorted tetrahedral geometry; and the other mercury atoms are bonded to one chlorine and more weakly to an equivalent chlorine of an adjacent chain. The two different mercury environments correspond to the moieties 'ButSHgCl.py' and 'ButSHgC1', respectively, of (ButSHgC1)2.py. The relevance of this work to the biological behaviour of mercury compounds and to the use of British anti-Lewisite as an antidote for mercury poisoning are discussed