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The nuclear magnetic resonance spectrum of B11 has been investigated in several glassy materials containing boron oxide. A value of 2.76±0.05 Mc for the nuclear quadrupole coupling constant of B11 has been calculated from the second-order quadrupole perturbation of the m = ½→—½ resonance line. The same quadrupole interaction has been observed in pure boron oxide, B2O3, soda-boric oxide binary glasses, and two commercial borosilicate glasses. The quadrupole coupling constant is interpreted as arising from the bonding electrons in BO3 groups which comprise the glass network in boron oxide. Addition of oxygen ions to the glass network induces a change in the boron configuration from BO3 planar groups to BO4 tetrahedra resulting in a reduction in the quadrupole interaction. This effect has been observed in the Na2O–B2O3 glasses and in Corning ``Pyrex'' and 707 borosilicate glasses.