The selective complexation of adamantane nitriles by tungsten pentacarbonyl

Adamantyl-1,3,4-oxathiazol-2-one is usually prepared as a mixture with 1-adamantanecarbonitrile. To separate these two compounds the mixture is reacted with thf·W(CO)₅, which selectively forms a complex with the nitrile. The resulting mixture can then be readily separated into pure compounds by sublimation. Characterization data are presented, including the X-ray crystal structure of the nitrile complex, which can be prepared directly from the reaction of the adamantyl nitrile and thf·W(CO)₅. (Crystal data for C₁₆H₁₅NO₅W: orthorhombic, space group Pmcn, a = 10.5869(19) Å, b = 14.0622(22) Å, c = 23.342(4) Å, V = 3475.0(11) ų, Z = 8, R = 0.042.) The nitrile can be recovered from the complex by reaction with P(C₆H₅)₃ followed with separation by sublimation. The reaction of the related 1-cyano-3-(1,3,4-oxathiazol-2-on-5-yl)-adamantane with thf·W(CO)₅ yields a complex in which the site of coordination is shown spectroscopically to be the nitrile moiety. Semi-empirical calculations at the PM3 level indicate that the oxathiazolone heterocycle may be a poor ligand due to the influence of the exo- and endo-cyclic oxygen atoms.