Master of Science (MS)
Semester of Degree Completion
Richard L. Keiter
The compounds trisdiphenylphosphine(tricarbonyl) metal and trisdiphenylvinylphosphine(tricarbonyl) metal of molybdenum and tungsten were prepared. These compounds were allowed to react with diphenylvinylphosphine and diphenylphosphine, respectively, in the presence of azobis(2-methyipropio)nitrile or potassium t-butoxide to yield the complex containing bis(diphenylphosphino) ethane as a chelated ligand.
The tris-substituted compounds showed a large degree of lability which prevented the isolation of the desired, (OC)3M(Ph2PCH2CH2PPh2)3, compound which contains three ditertiary phosphines acting as monodentate ligands.
Coordinated diphenylphosphine and diphenylvinylphosphine pentacarbonyl compounds of chromium, molybdenum and tungsten were prepared and allowed to react in the presence of potassium tertiary butoxide to yield bimetallic complexes containing bis(diphenylphosphino) ethane as a bridge. All six possible products were easily prepared in yields as high as 88% of recrystalized product. The carbonyl regions of the infrared spectra of the three symmetrical complexes (M=M') show bands as expected for pentacarbonyl moieties of C4V symmetry. Resolution of the two A1 absorptions in the mixed metal (unsymmetrical) complexes (CO)5Cr(diphos)Mo(CO)5 and (CO)5Cr(diphos)W(CO)5 was achieved (a difference of 9 cm-1) while not for the unsymmetrical compound (CO)5Mo(diphos)W(CO)5. Due to the natural abundance of tungsten - 183 (spin number of ½), the complex (CO)5183WPPh2CH2CH2Ph2PW(CO)5 resulted in an ABX type 31P NMR spectrum where 1JWP = 241.6 Hz, 3JPP = 36.6 Hz and 4JWP within the instrumental limits of measurements (± 2 Hz) is equal to zero.
Hansen, Nestor Paul, "Controlling the Number of Metal Sites to Which a Poly(tertiary Phosphine) Coordinates to Group 6 Metal Carbonyls" (1982). Masters Theses. 2905.