Addition compounds of MoO2Cl2 with chiral sulfoxides. First molecular structures of dioxomolybdenum complexes bearing chiral non-racemic sulfoxide as ligand

MoO₂Cl₂(L)₂ [L = (R)-(+)-methyl-p-tolylsulfoxide (R-MeTolSO) (1), methyl-p-tolylsulfoxide (MeTolSO) (2), 2-benzenesulfinyl-1,1-diphenylethanol (BSDPE) (3), 1-benzenesulfinyl-2-methyl-2-propanol (BSMP) (4), benzenesulfinylmethyl 4-methylphenyl ketone (BSMMPK) (5)], and MoO₂Cl₂(L) [L = BSDPE (6), BSMP (7), BSMMPK (8), (S,S)-bis(p-tolylsulfinyl)methane (S,S-TolSOCH₂SOTol) (9), bis(methylsulfinyl)methane (MeSOCH₂SOMe) (10), bis(phenylsulfinyl)methane (PhSOCH₂SOPh) (11)] have been synthesized by reacting a solution of MoO₂Cl₂(H₂O)₂ in diethyl ether with the corresponding ligand. The crystal and molecular structures of 1, 2, and 9 have been established by X-ray diffraction analysis. The ability of 1 and 9 as catalysts for the enantioselective reduction of sulfoxides to sulphides and the oxidation of sulphides to sulfoxides has been examined.     

Reciprocal inhibition of Cd and Pb sulfocomplexes for uptake in Caco-2 cells

Cadmium-lead interactions for uptake were studied in the TC7 clone of human enterocytic-like Caco-2 cells as a function of inorganic metal speciation. We have previously shown that Cd uptake in these cells involves both the free cation Cd2+ and chlorocomplex (CdCln(2-n)) species. Here we show 1.9 times higher uptake levels for 109CdCln(2-n) compared to 210PbCln(2-n). Reciprocal inhibitions of chlorocomplexes were observed with a much higher inhibitory effect of Cd compared to Pb. Replacing Cl- by NO3- increased both the level of aquo ion 109Cd2+ and 109Cd accumulation. In contrast, higher levels of 210Pb2+ did not favor 210Pb uptake. For both metals, higher uptake data were recorded in the presence of SO4(2-), leading to sulfocomplex formation, compared with Cl-. Reciprocal inhibitions were minimal at high-cation levels but were significant and comparable in the presence of sulfo-complexes. We conclude that, in addition to Cd2+ (but not Pb2+), sulfocomplexes of both metals would preferentially be taken up compared to chlorocomplexes. NRAMP2 is not involved in Pb2+ uptake, and the NRAMP2-mediated Cd2+ uptake is insensitive to Pb. Uptake of Pb chlorocomplexes could involve specific mechanisms but of very low affinity, whereas uptake of Pb sulfocomplexes occurs with high affinity.