- Conversion of some substituted phenols to the corresponding masked thiophenols, synthesis of a dinickel(n) dithiolate macrocyclic complex and isolation of some metal- And ligand-based oxidation products
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A modified preparation of the masked thiolate head unit 5-(2, 6-diformyl-4-methyIphenyl) dimethylthiocarbamate 6 is detailed and two new masked thiolate head units, 5-(2, 6-diformyl-4-tert-butylphenyl) dimethylthiocarbamate 7 and S-(2-formylphenyl) dimethylthiocarbamate 8, are prepared by this method. The synthesis, crystal structure, NMR spectra and electrochemical properties of the first macrocyclic complex to be derived from 7, [Ni2Ll](GO4)2, are discussed. Oxidation of [Ni2L2](CF3SO3)2 (L22- is derived from 6 and 1, 3-diaminopropane) with cerium(iv) ammonium nitrate led to the precipitation of the black complex [Ni2L2][Ce(NO3)6], which is believed to contain a single nickel(in) centre. This complex decomposes in DMF over time (24 hours) to form the red dinickel(n) complex [Ni2L2](NO3)2-2DMF which has been structurally characterised. Oxidation of [Ni2L3](CF3SO3)2 (L32- is derived from 6 and 1, 4-diaminobutane) with I2 results in ligand oxidation forming the metal free macrocycle (L3')2t which contains two five membered isothiazole rines. This is confirmed by the X-ray crystal structure determinations of (L3')(I, ), and (L3')(I):(I2)5. The Royal Society of Chemistry 2000.
- Brooker, Sally,Caygill, Graham B.,Croucher, Paul D.,Davidson, Tony C.,Clive, Derrick L. J.,Magnuson, Stephen R.,Cramer, Stephen P.,Ralston, Corie Y.
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- Controlled synthesis and reversible oxidation of a thiolate-bridged macrocyclic dinickel(II) complex
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The synthesis of S-(2,6-Diformyl-4-methylphenyl) dimethylthiocarbamate, a valuable thiolate-containing ligand precursor, is reported in detail for the first time. This precursor has considerable potential in biosite modelling studies. A macrocycle L and a related acyclic ligand L′ have been prepared, as complexes, from the precursor and 1,3-diaminopropane. The macrocycle was successfully templated by both zinc(II) and nickel(II) ions yielding [Zn2L(H2O)2][O3SCF3] 2·H2O 1 and the diamagnetic complex [Ni2L][ClO4]2 2, respectively. A single-crystal X-ray analysis of 1 showed the zinc ions to have trigonal-bipyramidal environments and the macrocycle to have a stepped conformation. In contrast, the structure determination of 2 revealed square-planar N2S2 co-ordination for NiII and a bowed macrocycle conformation which results in much shorter metal-metal and sulfur-sulfur separations than the stepped conformation adopted in the case of ZnII [average Zn ... Zn 3.351(1), S ... S 3.363(3) for 1 vs. Ni ... Ni 3.146(2), S ... S 2.839(5) A for 2]. Two one-electron oxidations, the first reversible and the second quasi-reversible, were observed for the dinickel(II) complex, whereas one irreversible two-electron oxidation was observed for the dizinc(II) complex. An acetal forms in the presence of ethanol and leads to the isolation of the acyclic trinickel(II) complex [Ni2L′2Ni][ClO4]2 3.
- Brooker, Sally,Croucher, Paul D.,Roxburgh, Fiona M.
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p. 3031 - 3037
(2007/10/03)
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