Reaction of the N,N-disubstituted bis-(hydroxylamino) ligand 2,6-bis [hydroxy(methyl)amino]-4-morpholino-1,3,5-triazine, H(2)bihyat, with (VOSO4)-O-IV center dot 5H(2)O in water for 6 h followed by the addition of methyl alcohol resulted in the isolation of the unsymmetrical mu-oxido divanadium(V) compound [(V2O2)-O-V(mu(2)-O)(bihyat)(hyta)(hyto)]center dot 3H(2)O (1 center dot 3H(2)O) and of the methylhydroxylamido derivative [(VO)-O-V(bihyat)(CH3NHO)]center dot H2O (2 center dot H2O). The N,N-disubstituted mono(hydroxylamino) ligands Hhyta, Hhyto, and CH3NHOH were formed by the decomposition of the ligand H(2)bihyat in the presence of vanadium. The structures of compounds 1 center dot 3H(2)O and 2 center dot H2O were determined by X-ray crystallography. The structure of 1 center dot 3H(2)O consists of one five-coordinate vanadium(V) atom and one six-coordinate vanadium(V) atom bridged by an oxido group and ligated to a tridentate bihyat(2-) and two bidentate hyta(-) and hyto(-) ligands, respectively. The two terminal oxido groups in 1 center dot 3H(2)O are syn-directed, lying on the same side of the V-O-V plane. The coordination environment of the vanadium atom in 2 center dot H2O approximates to a highly distorted pentagonal pyramid with the oxido ligand occupying the apical position. Compounds 1 center dot 3H(2)O and 2 center dot H2O were studied by multinuclear NMR (H-1, C-13, and V-51) to elucidate their solution structures. The V-51 NMR of 1 center dot 3H(2)O in anhydrous CD2Cl2 gave two signals at -199 and -508 ppm, which were assigned to the five- and six-coordinate vanadium(V) atoms, respectively. The resonance of the five-coordinate vanadium nucleus, in a field much lower than that expected from Rehder's [Inorg. Chem., 1988, 27, 584-587] referencing scale, was attributed to the low-energy ligand-to-metal charge transfer transition at 605 nm [epsilon(M)=5050 M-1 cm(-1)] of 1 center dot 3H(2)O according to Pecoraro et al. [J. Am. Chem. Soc., 1992, 114, 9925-9933], Electrospray ionization-mass spectrometry studies were used to follow the decomposition products of H(2)bihyat in the presence of vanadium.