139344-48-2Relevant academic research and scientific papers
Ligand substitution reactions in group 6 metal carbonyl complexes of a novel bicyclic ditertiary phosphine ether
Mason, Mark R.,Verkade, John G.
, p. 1514 - 1520 (1992)
The complexes fac-(1-P,P′,O)M(CO)3, where M = Mo or W and 1 is cis-1,5-bis((diphenylphosphino)-methyl)-3-oxabicyclo[3.3.0]octane, were found to react with the ligands L = acetonitrile, piperidine, pyridine, and P(OCH2)3CCH3 to yield two diastereomers of fac-(1-P,P′)M(CO)3(L) in each case. 1H and 13C NMR spectroscopic data suggest that the major isomer in each product is that in which the added ligand occupies the site originally occupied by the ether oxygen of 1 and that the minor isomer contains the new ligand in the position trans to this site. Carbon monoxide reacts with the complexes fac-(1-P,P′,O)M(CO)3 (M = Mo, W) to yield (1-P,P′)M(CO)4. Using 13CO, these reactions stereoselectively yield two diastereomers of fac-(1-P,P′)M(CO)3(13CO) in ratios of approximately 5:1 and 7:1 for M = Mo and W, respectively. A scheme involving the isomerization of diastereomeric five-coordinate square-pyramidal intermediates is discussed. The N-donor complexes fac-(1-P,P′)M(CO)3L, where M = Mo and W and L = acetonitrile, pyridine, and piperidine, were observed by infrared and 1H and 31P NMR spectroscopy to partially dissociate in solution, equilibrating with free L and fac-(1-P,P′,O)M(CO)3. This equilibrium was further substantiated by monitoring the exchange reaction between free and coordinated CD3CN in the presence of fac-(1-P,-P′)Mo(CO)3(NCCH3) using 2H NMR spectroscopy.
