New Reactions And Moleculer Structures Of Tungsten /molybdenum Complexes Supported By Me₃tacn Ligands

1,4,7-Trimethyl-l,4,7-triazacyclononane（Me₃tacn）is a cyclic amine ligand with both thermodynamic and kinetic stabilities.In past decades,transition metal complexes containing ligand Me₃tacn had been potentially applied in the fields of functional coordination chemistry and bioinorganic chemistry.High-purity ligand Me₃tacn was prepared in a high yield in the lab with new synthetic optimizing route.The new reactions and molecular structures of tungsten/molybdenum complexes supported by the Me₃tacn ligands are reported in the thesis.Treatment of M（CO）₆（M=W,Mo）with Me₃tacn in refluxing mesitylene afforded tungsten（0）/molybdenum（0）complexes（Me₃tacn）M（CO）₃（M=W,1a;Mo,1b）.Interaction of 1a or 1b with iodine in chloroform gave the corresponding oxide products,tungsten（II）/molybdenum（II）complexes[（Me₃tacn）M（CO）₃I]PF₆（M=W,2a;Mo,2b）,respectively.Reaction of 1a or 1b with concentrated hydrochloric acid（37%）in the air atmosphere resulted in the formation of tungsten（V）/molybdenum（V）complexes[（Me₃tacn）MOCl₂]PF₆（M=W,3a;Mo,3b）,respectively.Treatment of 1a or 1b with 30%H₂O₂ aqueous in tetrahydrofuran harvested decarbonation products tungsten（VI）/molybdenum（VI）complexes（Me₃tacn）MO₃·4H₂O（M=W,4a;Mo,4b）.The present eight various valences tungsten/molybdenum complexes（1a⁴a,1b⁴b）with the Me₃tacn ligands were well characterized by NMR,FT-IR and UV-Vis spectroscopies,of which molecular structures of complexes 1a,2a,4a,1b,3b and 4b were unambiguous established by single-crystal X-ray diffraction.Di-valent tungsten（II）/molybdenum（II）complexes 2a and 2b were selectively reacted with dialkyldithiocarbamate ligands,the corresponding seven tungsten（II）/molybdenum（II）complexes[（Me₃tacn）W（CO）₂（S₂CNR₂）]I（R=Me,5a;ⁱPr,7a）and[（Me₃tacn）Mo（CO）₂（S₂CNR₂）]PF₆（R=Me,5b;Et,6b;ⁱPr,7b;ⁿPr,8b;ⁿBu,9b）with bidentate dialkyldithiocarbamate ligands were thus obtained.The isolated seven tungsten（II）/molybdenum（II）-dtc complexes were characterized by NMR,FT-IRand UV-Vis spectrocopies,of which the molecular structures of complexes 5a,7a,5b,7b and 8b were confirmed by single-crystal X-ray diffraction.Structural analysis show that complexes 5a,7a,5b,7b and 8b are all di-valent cationic species,and the bidentate sulfur ligands are delocalized to the center of tungsten/molybdenum to form a seven-coordinate piano-stool structure.Penta-valent tungsten（V）/molybdenum（V）complexes 3a and 3b were selectively reacted with dialkyldithiocarbamate ligands,affording the corresponding six tungsten/molybdenum complexes 12a and 10¹4b with bidentate dialkyldithiocarbamate ligands.The complexes 12a and 10¹4b were characterized by IR and UV-Vis spectroscopies to speculate their possible structures.Reaction of the hexa-valent tungsten or molybdenum complexes 4a or 4b with copper perchlorate at a molar ratio of 4:1 gave the complexes{[（Me₃tacn）MO₃]₄Cu}（ClO₄）₂（M=W,15a;Mo,15b）.[ⁿBu₄N]₂[Mo₆O₁₉]was added to the complexes 15a and 15b dissolved in acetonitrile,respectively,obtaining the large anion-altered complexes{[（Me₃tacn）MO₃]₄Cu}[Mo₆O₁₉]（M=W,16a;Mo,16b）.The complexes 15a,15b,16a and 16b,were characterized by IR and UV-Vis spectroscopies,an indicative of copper-centered tetrahedral complexes bridged through four oxygen atoms of four（Me₃tacn）MO₃（M=W,Mo）moieties as metalloligands.Furthurmore,cyclic voltammetry measurements were performed on zero-valent,divalent,pentavalent,and hexavalent tungsten and molybdenum compounds,respectively,to study their corresponding redox properties.