Preparation and characterization of dimeric and tetrameric clusters of molybdenum and tungsten

Technical Report · Thu Oct 01 04:00:00 EDT 1981

DOI:https://doi.org/10.2172/5530833· OSTI ID:5530833

Ryan, T. R.

The cyclo-addition of two Mo/sub 2/Cl/sub 4/(P(C/sub 6/H/sub 5/)/sub 3/)/sub 2/(CH/sub 3/OH)/sub 2/ molecules has produced a new type of tetrameric molybdenum cluster, Mo/sub 4/Cl/sub 8/L/sub 4/. Structural characterization of this dimer revealed weak molybdenum-methanol bonding which was consistent with the observed reactivity of the compound. New synthetic methods were devised for the preparation of Mo/sub 4/X/sub 8/L/sub 4/ clusters where X = Cl, Br, I and L = PR/sub 3/, Po/sub 3/, RCN, CH/sub 3/OH. A scheme for the metal-metal bonding in these clusters was presented which was in agreement with the known structural features of Mo/sub 4/Cl/sub 8/(PR/sub 3/)/sub 4/, R = C/sub 2/H/sub 5/, n-C/sub 4/H/sub 9/. The preparation of the analogous W/sub 4/Cl/sub 8/(PR/sub 3/)/sub 4/ cluster from WCl/sub 4/ was accomplished by application of techniques used in the molybdenum syntheses. The single crystal x-ray structure revealed slight differences from the molybdenum analog which were rationalized in terms of the known behavior in dimeric tungsten and molybdenum species. The attempted preparation of a tetrameric tungsten cluster from W/sub 2/(mhp)/sub 4/ was unsuccessful (mhp = anion of 2-methyl-6-hydroxypyridine). Instead, the new tungsten dimer, W/sub 2/Cl/sub 2/(mhp)/sub 3/, was isolated which possessed a metal-metal bond order of 3.5. The x-ray crystal structure of the dimer revealed that the chlorine atoms were situated cis, one bound to each tungsten. Cyclic voltammetry showed that the compound could be reversibly reduced, presumably to a W/sub 2//sup 4 +/ dimer containing a quadruple metal-metal bond.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5530833
• Report Number(s): IS-T-952; ON: DE82005456
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALCOHOLS
AZINES
BROMIDES
BROMINE COMPOUNDS
CHLORIDES
CHLORINE COMPOUNDS
COMPLEXES
CRYSTAL STRUCTURE
DIMERS
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IODIDES
IODINE COMPOUNDS
METHANOL
MOLYBDENUM COMPLEXES
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHINES
PHOSPHORUS COMPOUNDS
PYRIDINES
TRANSITION ELEMENT COMPLEXES
TUNGSTEN COMPLEXES