The synthesis and structure of La5Pb3Z,Z  N,O. Interstitial derivatives of a Cr5B3-Type structure

Suitable proportions of La, La₄Pb₃ and La₂O₃ or LaN reacted in pressed pellets at 1050°–1250°C result in high yields of the title compounds. Single crystal X-ray studies of the oxide show it to be an isopointal, interstitial derivative of the Cr₅B₃ structure (I4/mcm, Z = 4, a = 8.6895(2) Å, c = 14.540(1) Å, R/R_w = 3.0/3.5%). Oxygen or nitrogen atoms are bound in (La2)₄ tetrahedra within chains along (0, 1 /2, z). Negligible dimerization of the type characteristic of Cr₅B₃ is indicated by the Pb2? Pb2 separation, 3.550(1) Å. The structure is compared with other related examples.