174715-55-0Relevant articles and documents
Spectroscopy, Molecular Structure, Electrochemistry, and Reactivity of Vanadium(IV,V) Imido Complexes of 5,7,12,14-Tetramethyldibenzo[b.i][1,4,8,11]tetraazacyclotetradecine
Schumann, Hans
, p. 1808 - 1813 (2008/10/09)
The synthesis of new imidovanadium(IV) complexes containing the tetradendate dianionic 5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecinato moiety (TMTAA2-) is reported. Stirring of either [(HTMTAA)VCl2]Cl or (TMTAA)VCl2 in solution with NH2R was used to prepare very moisture-sensitive, paramagnetic compounds of the type (TMTAA)V=NR (2, R = CH3, t-C4H5, C4H2, C6F5 and N(CH3)2) in high yields. Complexes 2 were characterized by EPR, IR, UV/vis, and mass spectroscopic techniques. CV measurements indicate a reversible le-oxidation to the corresponding diamagnetic vanadium (V) cations [(TMTAA)V=NR]+ (4). Complexes 4 were prepared in preparative scale by oxidation of 2 with 1 equiv of [(C5H5)Fe]SbF6 (3) and characterized by heteronuclear NMR, IR, and UV/vis spectroscopic methods. While the V=NR group in complexes 2 does not react with Cr(CO)5 or Pt(P(C6H5)3)2 under complexation, cycloaddition of 2a with hexfluoracetone has been observed. This reactivity has been compared to (TMTAA)V&=O (5), which is demonstrated to undergo addition and cycloaddition reactions with hexafluoracetone, hexfluorpropene oxide, sulfur trioxide and triflic anhydride (complexes 8a-d). Complex 4b (R = t-C4H9) has been crystallographically characterized and the results discussed with those of 5 and [(TMTAA)V=O]SbF6 (6).
