Synthesis and characterization of compounds containing discrete tetranuclear clusters and extended arrays of molybdenum atoms

Thumbnail Image
Aufdembrink, Brent
Major Professor
Committee Member
Journal Title
Journal ISSN
Volume Title
Research Projects
Organizational Units
Organizational Unit

The Department of Chemistry seeks to provide students with a foundation in the fundamentals and application of chemical theories and processes of the lab. Thus prepared they me pursue careers as teachers, industry supervisors, or research chemists in a variety of domains (governmental, academic, etc).

The Department of Chemistry was founded in 1880.

Dates of Existence

Related Units

Journal Issue
Is Version Of

Improved synthetic pathways to the Mo(,4)Cl(,8)L(,4) cluster compounds were elucidated which provide a facile entrance to the synthesis of new four metal atom clusters. The new tetranuclear clusters, with the stoichiometry R(,4)Mo(,4)Cl(,12) (R = Et(,4)N, Pr(,4)N, O(,4)P), were prepared by the reaction of tetraalkylammonium or tetraphenylphosphonium chlorides with the rectangular tetrameric cluster Mo(,4)Cl(,8)L(,4);One electron oxidation of Mo(,4)Cl(,12)('4-) by I(,2) or dichlorophenyliodine yielded the Mo(,4)Cl(,12)('3-) cluster anion, which was shown to exist as two geometric isomers, both of which are fragments of the larger hexa- nuclear cluster anion Mo(,6)Cl(,14)('2-). The metal atoms in (Et(,4)N)(,3)Mo(,4)Cl(,12) form an opened tetrahedron or "butterfly". In O(,4)P (,3)Mo(,4)Cl(,12), Pr(,4)N (,3)- Mo(,4)Cl(,12), and O(,4)As (,2) Et(,4)N Mo(,4)Cl(,12) the metal atoms form a planar rhomboidal cluster unit. Bond distances in both cluster units are indicative of strong metal-metal bonding. The reasons for the adop- tion of one configuration over the other are not completely clear, but extended Huckel calculations have shown that Jahn-Teller dis- tortions are responsible for the observation of a planar rhomboidal rather than square cluster geometry for the planar units. Magnetic susceptibility and electron paramagnetic resonance studies of O(,4)P (,3)Mo(,4)Cl(,12) and Pr(,4)N (,3)Mo(,4)Cl(,12) are consistent with the assign- ment of one unparied electron, delocalized over the cluster unit;The ternary molybdenum oxide, Sn(,0.9)Mo(,4)O(,6), was synthesized by high temperature reactions in sealed molybdenum tubes. The struc- ture of this compound is dominated by metal-metal bonded octa- hedal clusters which are fused on trans edges to form infinite chains through the lattice. Four such clusters are interconnected to form a tetragonal tunnel occupied by Sn. The short Sn-Sn distance along the channel, (2.836 (ANGSTROM)), is suggestive of Sn-Sn bonding which was also indicated by extended Huckel calculations. Disorder observed along the channel where the Sn atom resides is believed to be a consequence of the Sn-Sn bonding and the non-stoichiometry observed for the compound. Resistivity studies show the compound;is metallic. The compound exhibits weak, temperature independent paramagnetism; ('1)DOE Report IS-T-1176. This work was performed in part under contract W-7405-eng-82 with the Department of Energy and in part under a grant (CHE-8406822) from the National Science Foundation.

Subject Categories
Tue Jan 01 00:00:00 UTC 1985