The synthesis of new imidovanadium(IV) complexes containing the tetradendate dianionic 5,7,12,14-tetramethyldibenzo[b,i][1, ,4,8,11]tetraazacyclotetradecinato moiety (TMTAA(2-)) is reported. Stirring of either [(HTMTAA)VCl2]Cl or (TMTAA)VCl2 in solution with NH(2)R was used to prepare very moisture-sensitive, paramagnetic compounds of the type (TMTAA)V=NR (2, R = CH3, t-C4H9, C6H5. 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 of2 with 1 equiv of [(C5H5)(2)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).