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/Rw = 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.