engleski

New dinuclear molybdenum(V) complexes with thioligands

The fact that molybdenum-sulfur bonds are present in molybdoenzymes has extensively stimulated research in molybdenum complexes with sulfur ligand environments. This is particularly true for oxo complexes with molybdenum in its higher oxidation states. In the continuation of our research on such complexes with thioligands from the reactions of [Mo_2O_3(acac)_4] (acac = 2,4-pentandionato) with thiobenzoic acid and 1,1,1-trifluorothioacetylacetone we have isolated two novel complexes: [Mo_2O_2S_2(OSCC_6H_5)_2] (1) and [Mo_2O_3{CH_3C(S)CHC(O)CF_3}_4] (2). The neutral dimer (1) exhibits the affinity towards different donor ligands such as pyridine and gama-picoline so that the corresponding [Mo_2O_2S_2(OSCC_6H_5)_2(C_5H_5N)_2] (3) and [Mo_2O_2S_2(OSCC_6H_5)_2(C_6H_7N)_2]ˇ2H_2O (4) complexes were also prepared. The complexes (2), (3) and (4) were crystaline substances and their structures determined by X-ray structure analysis. Each molybdenum atom in the centrosymetrical complex molecule of (2) is in a distorted octahedral coordination being bonded to two and two sulfur atoms from two bidentate 1,1,1- trifluorothioacetylacetonate ligands and to one bridging and one terminal oxo-oxygen atom. The fluorine atoms of both 1,1,1- trifluorothioacetylacetonates are disordered over six positions. The complexes (3) and (4) are analogous and dinuclear, both containing Mo_2O_2S_2 cores with two Mo atoms linked by a Mo-Mo single bond. The Mo atoms are octahedrally coordinated by oxo-oxygen, two bridging sulfido-sulfurs, one nitrogen and from pyridine or gama-picoline molecules and one sulfur and oxygen atom from bidentately bonded thiobenzoato ligands. The complex molecule (3) has crystallographically imposed two-fold symmetry axis while the complex molecule (4) exhibits a pseudo two-fold symmetry.

Crystal structures; Molybdenum(V) complexes; Thiobenzoato complexes; 1;1;1- Trifluorothioacetylacetone; Thioligands

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