To ascertain what role structural factors-and, hence, by implication, bonding factors-play in the pronounced acidity of dibenzenesulfonamide (pKa = 1.45), the structures of the acid itself, (C6H6S02)2NH, and the sodium salt, Na+(C6H5S02)2N-, have been determined. For (CeH5S02)2NH: space group, P2i/c; Z = 4; d0 = 1.470

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Figure 4.-The coordination polyhedron about the Pr(II1) ion showing the monocapped square-antiprismatic configuration.is bent down toward plane B as can be seen in Figure 3. Since this complex contains constraints of chelating as well as three different kinds of atoms in the coordination sphere, it does not lend itself to detailed analysis of the coordination polyhedron. Day and Hoard2; have noted that the quasi-Cd axis [N(1)-Pr] corresponding to the Cdv symmetry of the idealized monocapped square antiprism must generate four axes [Pr-N(l), Pr-N(2), Pr-N(2)', and Pr-Cl(1)] normal to which are observed one-five-three layering of the ligated atoms. Examination of the model does show such layering.A reasonable pattern of three-dimensional hydrogen bonding (Table 111) can be proposed as O(1) + Cl(1)"' and O(5) O ( 2 ) + Cl(2) and O(4) O ( 3 ) + Cl(2) and C1(l)vr O(4) + C1(2)11 and C1(2)Ir1 O(5) + C1(2)Iv and C1(2)v This scheme thus links each complex ion to all six of its neighboring ions via hydrogen bonding. This threedimensional hydrogen bonding is manifested in the excellent crystals corresponding to the octahydrated complex. The crystal and molecular structure of tris( glycinato)chrornium( 111) monohydrate, Cr( C S H~N O~)~ HzO, has been determined by single-crystal X-ray analysis. The cell constants are a = 6.256 ( l ) , b = 14.649 (l), c = 12.267 (1) A, and fl = 100.39 (1)'.The space group is P&/c and with 2 = 4 the calculated density is 1.755 g/cin3 compared to the observed 1.76 (1) g/c1n3. Scintillation counter diffractonietry was used to measure the intensities of 2631 independent reflections significantly above background. The phase problem was solved by the application of direct methods and the structural parameters refined by a block-diagonal least-squares procedure to a final R of 0.0266. All hydrogen atoms in the structure were located and their positional parameters were refined. Anisotropic thermal parameters were used for all atoms except hydrogen. The chromium ion is octahedrally coordinated by three glycinato ligands so that the three nitrogen atoms are mutually cis.

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