Spectral and thermogravimetric studies of oxohalobis-(4-morpholinyldithiocarbamato)molybdenum(V) complexes

Molybdenum(V) complexes [MoOX(4-Morphdtc)2] (X = F, Cl, Br or I; 4-Morphdtc = 4-morpholinyldithiocarbamate) have been prepared from molybdenum trioxide using hydrazine hydrohalides as reducing agents. The magnetic moment values at ca. 1.65 B.M. and e.p.r. studies indicated that the complexes are mononuclear and that molybdenum is in + 5 oxidation state. The i.r. spectral bands at 1500 and 960 cm-1 suggest that the dithiocarbamate acts as a univalent bidentate ligand and the bands at 930 cm-1 confirms the presence of a MoO3+ moiety in the complex. The low conductivity values for the complexes in N, N-dimethylformamide indicate that the complexes are non-ionic. The [MoOX(4-Morphdtc)2] complexes (X = F, Cl or Br) decompose in the first step by the loss of one dithiocarbamate group, whereas in [MoOI(4-Morphdtc)2] the iodine atom is lost in the first step. The second and third steps lead to the formation of MoS3 and MoO3, respectively. A six coordinate structure around Mo with an oxo, halo and two dithiocarbamate group is proposed. (orig.)