COORDINATIVE INTERCALATION OF ALKYLAMINES INTO LAYERED ZINC PHENYLPHOSPHONATE - CRYSTAL-STRUCTURES FROM X-RAY-POWDER DIFFRACTION DATA

Zinc phenylphosphonate monohydrate takes up 1 mol of amine when contac ted with liquid primary alkylamines. The mechanism of intercalation in volves replacement of the coordinated water molecule by the amine mole cules. Although the composition of the intercalate Zn(O3PC6H5)(RNH(2)) is consistent with the analytical and spectroscopic data, there exist discrepancies in the observed interlayer d spacings of the intercalat e with respect to that in the host compound. The a spacing for the pro pylamine intercalate is in fact smaller than that in zinc phenylphosph onate itself. In order to understand this feature specifically and to explain the mechanism of amine intercalation in metal phosphonates in general, we have determined the structures of the intercalates. The st ructures of Zn(O3PC6H5)(RNH(2)), R = -C3H9 (1), -C4H11 (2), -C5H13 (3) , were solved ab initio from X-ray powder diffraction data and refined by Rietveld methods. All the compounds are isostructural, and they cr ystallize in the monoclinic space group P2(1)/c with a = 13.9783(3) An gstrom, b = 8.791(2) Angstrom, c = 9.691(2) Angstrom, and beta = 102.0 8(1)degrees for 1, a = 14.698(4) Angstrom, b = 8.957(3) Angstrom, c = 9.712(3) Angstrom, and beta = 102.465(3)degrees for 2, and a = 16.267( 3) Angstrom, b = 8.935(2) Angstrom, c = 9.695(2) Angstrom, and beta = 102.32(1)degrees for 3. The structures of these intercalates are new a nd are different from that of the host compound although all of them a re layered. In the intercalate the zinc atoms are tetrahedrally coordi nated as opposed to octahedral coordination in the host compound.