Carbon-13 nuclear magnetic resonance studies of a solid inclusion complex

A solid inclusion complex containing n-hexane as the mobile guest component was studied via cross polarization nuclear magnetic resonance techniques. The hexane is found to yield a cross polarization spectrum, demonstrating that its motion in the lattice is anisotropic. The hexane also yields a relatively sharp spectrum with the proton decoupler off, showing reduced /sup 1/H-/sup 13/C scalar splittings. A theory developed by Sack and Pople to account for the effect of /sup 14/N relaxation on the appearance of the /sup 1/H spectrum of NH/sub 3/ is applied here to account for the reduced splitting in terms of a proton-proton flip-flop mechanism. A flip-flop rate of 110-135 s/sup -1/ is determined for the methylene groups. The /sup 13/C spin-spin relaxation time is used in a rough characterization of rotational motion of the hexane. The qualitative correlation time obtained is intermediate between that for a liquid and that for a rigid solid. 7 figures.