Synthesis of novel molybdenum(V) complexes: Structural characterization of two thiosemicarbazonato complexes [MoOCl2{C6H4(O)CH:NNHC:SNHC6H5}] and [MoOCl2{C10H6(O)CH:NNHC:SNHC6H5}] · CH3CN, and two oxohalomolybdates NH4[MoOCl4(CH3CN)] and [C5H5NH]2[MoOCl5]

Mononuclear oxomolybdenum(V) complexes with thiosemicarbazonato ligands as condensation products of aldehydes (salicylaldehyde, 2-hydroxynaphthaldehyde) with thiosemicarbazides (H2NNHC:SNHR; R = H, CH3, C6H5) were prepared. The [MoOCl2HL] complexes (HL = thiosemicarbazonato ligand) were characterized by chemical analysis, IR spectroscopy, thermogravimetry and two of them, [MoOCl2{C6H4(O)CH:NNHC:SNHC6H5}] and [MoOCl2{C10H6(O)CH:NNHC:SNHC6H5}] · CH3CN, by single-crystal X-ray structural analysis. In both complexes the MoO3+ core is coordinated by a monobasic tridentate ONS thiosemicarbazonato ligand and two chloro ligands. The coordination around the molybdenum atom is a distorted octahedron. NH4[MoOCl4(CH3CN)] and unstable (C5H5NH)2[MoOCl5] · CH2Cl2 were isolated from the acetonitrile solution of (NH4)2[MoOCl5] and from the acetonitrile and dichloromethane (1:1) solution of (C5H5NH)2[MoOCl5], respectively.Isolation and structural characterization of NH4[MoOCl4(CH3CN)] from the acetonitrile solution suggests the [MoOCl4(CH3CN)]− anion to be the reaction intermediate in the synthesis of molybdenum(V) thiosemicarbazonato complexes.(C5H5NH)2[MoOCl5] · CH2Cl2 is a rare example of a structurally characterized simple oxohalomolybdate(V) with a six-coordinate octahedral [MoOCl5]2− anion.

Graphical abstractEight mononuclear oxomolybdenum(V) complexes were prepared. All the complexes were characterized by chemical analysis, IR spectroscopy, thermogravimetry and four of them, [MoOCl2{C6H4(O)CH:NNHC:SNHC6H5}], [MoOCl2{C10H6(O)CH:NNHC:SNHC6H5}] · CH3CN, NH4[MoOCl4(CH3CN)] and (C5H5NH)2[MoOCl5] · CH2Cl2, by single-crystal X-ray structural analysis.Figure optionsDownload full-size imageDownload as PowerPoint slide