Charge Distribution in the Light-Atom Mineral Kernite

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Science  14 Apr 1972:
Vol. 176, Issue 4031, pp. 165-166
DOI: 10.1126/science.176.4031.165


A charge density analysis of accurate x-ray data for the mineral kernite Na2B4O6(OH)2. 3H2O indicates that the sodium and boron atoms have partial positive charges of 0.4 to 0.5 unit and 0.4 to 0.7 unit, respectively, whereas the oxygen atoms have negative charges of about 0.4 to 0.5 unit. The best agreement with the intensities and with the experimental scale factor is obtained with contracted molecule-optimized atomic orbitals. Difference density maps based on high-order parameters show more density in B-O than in Na-O bonds, thus supporting the covalent nature of the bonds between boron and oxygen atoms.