Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Complexes of niobium and tantalum containing metal-metal bonds

Thesis/Dissertation ·
OSTI ID:6616358
A new entry into the area of low valent niobium and tantalum complexes containing metal-metal bonds is described. M/sub 2/X/sub 6/ (..mu..-THT)(THF)/sub 2/ complexes, where M = Nb or Ta, X = Cl or Br and THT - tetrahydrothiophene, are conveniently synthesized via the reaction of M/sub 2/M/sub 6/(THT)/sub 3/ with THF (THF = tetrahydrofuran). Unlike M/sub 2/X/sub 6/(THT)/sub 3/, M/sub 2/X/sub 6/(..mu..-THT)(THF)/sub 2/ can be easily reduced by sodium amalgam. In THF and in the presence of THT, complexes of the type M/sub 2/X/sub 6/(..mu..-THT)/sub 3//sup 2 -/ form. Salts of these compounds can also be synthesized directly from the metal pentahalides in a two step, one pot reaction in which M/sub 2/X/sub 6/(THT)/sub 3/ is an intermediate. The M/sub 2/X/sub 6/(..mu..-THT)/sub 3//sup 2 -/ complexes have a face-sharing bioctahedral structure with metal-metal triple bonds, the first reported for niobium or tantalum. These compounds are relatively inert, but (Nb/sub 2/Cl/sub 6/(..mu..-THT)/sub 3//sup 2 -/ does reach with pyridine and with a solution of acetic acid/acetic anhydride. These reactions and those of some of the sodium salts are described. In general, trinuclear complexes of niobium and tantalum are rare, and this type of discrete trinuclear complex, which contains one capping, three bridging and nine terminal ligands, has been seen only once before for the group 5 metals, although many examples of similar group 6 metal complexes are known. Full details of the synthesis and characterization of these complexes are described and an interpretation of their electronic structures is given.
Research Organization:
Texas A and M Univ., College Station (USA)
OSTI ID:
6616358
Country of Publication:
United States
Language:
English