Rhenium imido compounds

In the imido series, however, the rhenium-nitrogen distances for rhenium(V) average 180.1pm, which is somewhat longer than the average of the values for several rhenium(VII) compounds, 174 pm. The one terminal thio-rhenium bond, 209.2 pm, is significantly shorter than any of the p-S bonds, which average 231pm. 

The direct aminolysis of metal oxides with primary amines is a useful synthetic route for imido compounds of rhenium and osmium (equation 41). 

D. Hydrolysis, Hydrosulfidolysis and Aminolysis of Imido-rhenium Compounds... 

Compilation of Rhenium-Oxygen and Other Bond Distances in Oxo-, and Imido- and Thio-rhenium Compounds... 

In rhenium compounds that contain two metal-imido ligands, these tend not to occupy positions trans to one another for the same reason. A trigonal-bipyramidal geometry has been identified in 2 and 3, even to the extent that the potentially chelating ligand Ph2PCH2PPh2 acts as a monodentate ligand. 

Coordination compounds of rhenium are known with the metal in the oxidation states +1 up to +7. The oxidation state with the by far most representatives is that of +5. The cF configuration is readily stabilized by multiply bonded ligands such as oxo, nitrido, or imido. 

By far, the largest number of structurally characterized rhenium complexes contain the metal in the oxidation state +5 . This can be attributed to the high stability of the rhenium(V) oxo, nitrido, and imido cores with a great variety of ligand systems, but is doubtlessly also related to the fact that rhenium complexes are frequently used as nonradioactive model compounds for the development of technetium radiopharmaceuticals. The dominance of 0 , and NR ligands can be... 

Compounds of the composition [ReOCl3(N N)] have also been isolated with pyridine-2-aldi-mine and rr-acidic arylazopyridine and arylazoimidazole ligands." The products (101) are readily reduced by oxygen atom transfer reactions from Re to phosphorus atoms of phosphines which results in the formation of rhenium(III) complexes. Depending on the reaction condition and the phosphines used either mononuclear or binuclear compounds are formed." " Azo splitting reactions with arylazopyridines give access to arylimido and binuclear oxo/imido com-plexes. "" ... 

The electrochemical properties of a number of isostructural rhe-nium(V) oxo, rhenium(V) imido, osmium(VI) nitrido, of formula [M(E)(X)(Y)(Tp )] (Tp = Tp or Tp, E = O, N-tolyl, N X, Y = hydrocarbyl, halide, triflate), have been described. The reactivity of these complexes as inner-sphere oxidants does not correlate with their peak reduction potentials, whereas the ease of the oxidation of these compounds well parallels their reactivity as oxidants.206... 

The brown complex is soluble in acetone and dichloromcthane. Tire v(Tc=N) vibration is reported at 951 cm The structure of the analogous rhenium compound shows the ligands (NCf,H4PPh2) and (HNC(,H4PPh2)" twisted to each other, with the imido group bonded irons to a chlorine atom, and the other chlorine atom coordinated cqua-torially [289],... 

Studies of the chemistry of phenylimido rhenium complexes have normally employed Re(NPh)Cl3(PPh3)2 as the starting material because of its easy preparation from aniline and the readily available compound ReOClj(PPh3)2. Tungsten imido complexes cannot be prepared similarly. The lack of good preparative methods leading to suitable starting materials has limited studies with this metal. 

---