CRYSTAL STRUCTURE OF KAOLINITE: DIMETHYLSULFOXIDE INTERCALATE

Abstract- The crystal structure of the kaolinite: dimethylsulfoxide (DMSO) intercalate (P 1, a = 5.187(2), b = 8.964(3), c = 11.838(4) A, a = 91.53(1) ~ = 108.59(2) ~ T = 89.92(1)*) has been determined using spectroscopic and X-ray and neutron powder diffraction data. Both the X-ray and neutron powder diffraction patterns were refined. Solid-state ~3C, 298i, and 27A1 nuclear magnetic resonance data and previously collected infrared spectroscopic data provided a useful starting model for structural refinement. Due to the extreme overlap of reflections of this low-symmetry unit cell, the Rietveld method proved inadequate, and quasi-single crystal methods were employed. Each DMSO molecule was found to be triply hydrogen bonded above the octahedral vacancy in the glbbsitic sheet of the kaolinite layer. One methyl group is keyed into the ditrigonal hole in the tetrahedral sheet with the other S--C bond parallel to the sheet. The DMSO molecules are accommodated by significant horizontal displacement ofindividual kaolinite layers to achieve almost perfect overlap of the octahedral vacancy by the adjacent ditrigonal hole