Homonuclear and heteronuclear oxo-bridged compounds of the transition elements

2. Molybdenum and tungsten

Studies of some dioxo molybdenum (VI) complexes of a polydentate ligand

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 atca. 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 inN, 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 groups is proposed.

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

Iron-molybdenum heterometallic complexes, FeMoO2R4-(H2O) (R=8-quinolinolate, diethyldithiocarbamate, 4-morpholinyl-dithiocarbamate and piperidinyldithiocarbamate), have been prepared from iron(III) molybdate. T.l.c. and x-ray diffraction studies indicate that the complexes are discrete species. The complexes are non-electrolytes in dimethylformamide. Magnetic measurements suggest that the iron and molybdenum are in the III and V oxidation states, respectively, with octahedral geometry around each atom. I.r. spectral studies indicate the presence of MoO3+ and FeOMo bridges and the monoionic bidentate nature of the ligands. Electronic spectral and thermal decomposition studies on these complexes are reported.

K. Seetharamiah Nagaraja

Papers

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

Mixed metal complexes of iron-molybdenum with 8-quinolinolate and dithiocarbamates