was used to test for possible silicon incorporation in ErN^* synthesized from |(Me3Si)2N)3Er contaminated with ~2 mol % LiN(SiMe3)2; an upper limit of Si as 1 wt % was found. The silicon content of Er203 (Aldrich 99.9%) used to prepare ErCl3 is less than 15 ppm, and thus trace Si incorporation is possible. Mass balance supported the contention that the ammonolysis of ¡(Me3Si)2N}3Ln proceeded smoothly, as indicated by the calculated and observed weight losses in Table I.A distinct advantage to the melt technique concerns the ready preparation of Ln^Ln'^N,.* solid solutions, provided the constituents possess compatible ionic radii. Following the standard procedure,20 a melt containing a 1:1 ratio of {(Me3Si)2N|3Y and |(Me3Si)2N}3Sm in addition to traces of LiCl (vide infra)21 led to Yo.5Smo.5N1-* after annealing at 600 °C for 24 h. The diffraction lines (found: a = 4.968 (3) Á) of the mixed lanthanide compound are broad and between those of the binary compounds (average of literature23 values: a = 4.971 Á), indicative of a solid solution (see supplemental Figure l).11•27 Onset of Crystallization. When higher purity {(Me3Si)2N}3Ln (Ln = Y, La, Sm, Eu, Tb, Yb; <0.5% LiN(SiMe3)2) was utilized in Scheme I, an annealing temperature of 850 °C (24 h) was required to provide Ln^,*. However, if 1-3 mol % LiN(SiMe3)2 was present in {(Me3Si)2N|3Ln (Ln = Pr, Nd, Er) or when 10-15 mol % was ground and melted together with higher purity i(Me3Si)2N}3Yb, crystalline EnN^* formed upon annealing for 24 h at 575 °C. Rapid ammonolysis of LiN(SiMe3)2 must occur, and the resulting LiNH2 (tetragonal, 14, a = 5.016 Á, c = 10.22 Á)28 catalyzes the crystallization of LnN[-x. Transport processes mediated by protons or lithium from trace LiNH2 (i.e., miner-Supplementary Material Available: XRD patterns for Yg^Smo ¡N^, YN,_X, and SmN!-* prepared from a melt containing a 1:1 ratio of j(Me3Si)2N|3Y and |(Me3Si)2N|3Sm in addition to traces of LiCl (Figure 1) (1 page). Ordering information is given on any current masthead page.
