Lanthanido ammonium cations [NM4]9+ as main structural features in lanthanide(III) nitride chalcogenides and their derivatives

The A-Type Ln4N2S3 Series: New Nitride Sulfides of the Light Lanthanoids (Ln = Ce–Nd)

“…Thus, a single strand is surrounded by a total of six more in the manner of a hexagonal rod packing. In analogy to all the rare-earth metal(III) nitride chalcogenides and their halide derivatives known to date [1][2][3], the N 3− anions are again surrounded by a more or less distorted tetrahedron of Ln 3+ cations, in which the four N 3− -Ln 3+ distances (228-241 pm) differ by a maximum of 13 pm and the angles range between 97° and 114° (Table 4). In fact, the typical characteristic of the structural construction is actually created by the individual linkage of these [NLn4] 9+ tetrahedra.…”

“…As adapted from the standard methodology reported in [1], the new lanthanoid nitride sulfides Ln4N2S3 (Ln = Ce-Nd) are obtained by the reaction of lanthanoid metal (Ln; ChemPur: 99.9%) with sulfur (S; ChemPur: 99.9999%) and lanthanoid tribromide (LnBr3; prepared from CeO2, Pr6O11 and Nd2O3 (all: Johnson-Matthey: 99.999%) by the ammonium-bromide method [23]) and cesium azide (CsN3; Ferak: 99.9%). On adding cesium bromide (CsBr; ChemPur: 99.9%) as flux almost black, rod-shaped single crystals of the target compounds Ln4N2S3 (Ln = Ce-Nd) that reflect strongly in the In addition to La 4 N 2 S 3 [7,12] crystallizing dimorphously in the A-La 4 N 2 S 3 -and in the B-Pr 4 N 2 S 3 -type structures and Ce 4 N 2 Se 3 , which is observed either with the Nd 4 N 2 Se 3 -or with the Ce 4 N 2 Te 3 -type arrangement, now the next nitride sulfide of the lanthanoids with the composition Pr 4 N 2 S 3 can represent both the A-and B-type structures.…”

“…As adapted from the standard methodology reported in [1], the new lanthanoid nitride sulfides Nonetheless, the process of the reaction according to 34 Ln + 27 S + 6 CsN 3 + 2 LnBr 3 → 9 Ln 4 N 2 S 3 + 6 CsBr (Ln = Ce-Nd), which can be classified as redox metathesis with the formation of CsBr as driving force, is not complete. Besides some white amorphous parts, which are presumably produced by undesired reactions with the silica-ampoule walls, mostly brown rods that could be characterized as Ln 3 NS 3 representatives (Ln = Ce-Nd) [24] were also obtained.…”

“…The crystal structures of all ternary lanthanide(III) nitride chalcogenides known so far (Ln 3 NCh 3 , Ln 4 N 2 Ch 3 , Ln 5 NCh 6 , Ln 23 N 5 Ch 27 , and Ln 13 N 5 Ch 12 ) and their halide derivatives (Ln 3 N 2 ChX, Ln 4 NCh 3 X 3 , Ln 5 N 2 Ch 4 X, Ln 5 N 3 Ch 2 X 2 , and Ln 6 N 3 Ch 4 X; Ln = La-Nd, Sm, Gd-Ho; Ch = S, Se, Te; X = Cl, Br) are dominated by N 3− anions in a tetrahedral coordination of Ln 3+ cations [1][2][3]. A very interesting structural behavior is exhibited by the nitride chalcogenides with the composition Ln 4 N 2 Ch 3 , which occur in seven different crystal structure types.…”

“…As the main structural feature of the orthorhombic A-La 4 N 2 S 3 -type structure [7] (Pnnm, Z = 2), N 3− -centered (Ln 3+ ) 4 tetrahedra, which first arrange as pairs [N 2 Ln 6 ] 12+ of two edge-shared [NLn 4 ] 9+ units, occur. These are further connected via their four free vertices to form double chains 1 ∞ {([NLn 2 ] 2 ) 6+ }. For the first time, an arrangement of interconnected [NLn 4 ] 9+ tetrahedra fused to layers is observed in the monoclinic Nd 4 N 2 Se 3 -type structure [8][9][10][11] (Ln = La-Nd; C2/c, Z = 4).…”