Nickel(II) N-benzyl-N-methyldithiocarbamato complexes as precursors for the preparation of graphite oxidation accelerators
Résumé
The nickel(II) N-benzyl-N-methyldithiocarbamato (BzMedtc) complexes [Ni(BzMedtc)(PPh3)Cl] (1), [Ni(BzMedtc)(PPh3)Br] (2), [Ni(BzMedtc)(PPh3)I] (3) and [Ni(BzMedtc)(PPh3)(NCS)] (4) were synthesized using the reaction of [Ni(BzMedtc)¬2] and [NiX2(PPh3)2], where X = Cl, Br, I and NCS. Subsequently, the complex 1 was used for the preparation of [Ni(BzMedtc)(PPh3)2]ClO4 (5), [Ni(BzMedtc)(PPh3)2]BPh4 (6) and [Ni(BzMedtc)(PPh3)2]PF6 (7). The obtained complexes 1-7 were characterized by elemental analysis, thermal analysis and spectroscopic methods (IR, UV Vis, 31P{1H}-NMR). The results of the magnetochemical and molar conductivity measurements proved the complexes as diamagnetic non-electrolytes (1-4) or 1:1 electrolytes (5-7). The molecular structures of 4 and 5∙H2O were determined by a single crystal X ray analysis. In all cases, the Ni(II) atom is four-coordinated in a distorted square-planar arrangement with the S2PX, and S2P2 donor set, respectively. The catalytic influence of selected complexes 1, 3, 5, and 6 on graphite oxidation was studied. The results clearly indicated that the presence of the products of thermal degradation processes of the mentioned complexes have impact on the course of graphite oxidation. A decrease in the oxidation start temperatures by about 60-100 °C was observed in the cases of all the tested complexes in comparison with pure graphite.
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