Nitrogen‐Rich Compounds of the Lanthanoids: The 5,5′‐Azobis[1H‐tetrazol‐1‐ides] of some Yttric Earths (Tb, Dy, Ho, Er, Tm, Yb, and Lu)

Abstract

A set of N-rich salts, 3 -9, of the heavy lanthanoids (terbium, 3; dysprosium, 4; holmium 5; erbium, 6; thulium, 7; ytterbium, 8; lutetium, 9) based on the energetic 5,5'-azobis[1H-tetrazole] (H 2 ZT) was synthesized and characterized by elemental analysis, vibrational (IR and Raman) spectroscopy, and Xray structure determination. The synthesis of the lanthanoid salts 3 -9 was performed by crystallization from concentrated aqueous solutions of disodium 5,5'-azobis[1H-tetrazol-1-ide] dihydrate (Na 2 ZT · 2 H 2 O; 1) and the respective Ln(NO 3 ) 3 · 5 H 2 O and yielded large rhombic crystals of the type [Ln(H 2 O) 8 ] 2 (ZT) 3 · 6 H 2 O in ca. 70% of the theoretical yield. The compounds 3 -9 are isostructural (triclinic space group P1 ) to the previously published yttrium salt 2; they show, however, a clear lanthanoid contraction of several crystallographic parameters, e.g., the cell volume or the LnÀO bond lengths of the Ln 3þ ions and the coordinating H 2 O molecules. The lanthanoid contraction influences the strengths of the H-bonds, which can be observed as a red shift by 4 cm À1 in the characteristic IR band, in particular from 3595 cm À1 (3) to 3599 cm À1 (9). In good agreement with previous works, 2 -9 are purely salt-like compounds without a coordinative bond between the tetrazolide anion and the Ln 3þ cation.

Nitrogen‐Rich Compounds of the Lanthanoids: The 5,5′‐Azobis[1H‐tetrazol‐1‐ides] of the Light Rare Earths (Ce, Pr, Nd, Sm, Eu, Gd)

“…After five days, crystallization started and led to a pure, crystalline product with a satisfactory yield (between 25 and 67%). The yield was smaller than in the case of the previously studied heavier and more acidic REE [22]. This fact evidences that acidic decomposition of the (ZT) 2À by the Lewis acidic Ln 3þ cannot be responsible for the lower yield.…”

“…This article is the second contribution of our work on N-rich compounds of the lanthanoids, and follows [22]. In the present study, we report on the synthesis, crystal structures, and vibrational spectroscopy of the isotypic 5,5'-azobis[1H-tetrazol- (1) in aqueous solution at elevated temperature in the initial phase of the reaction (Scheme).…”

Structures and Energetic Properties of Two New Salts Comprising the 5,5'-Azotetrazolate Dianion

“…Recrystallization from a minimum amount of reagent grade acetone afforded yellow, prism-shaped single-crystals which were found to be suitable for X-ray diffraction ( Figure 1). Tetraphenylphosphonium-5,5'-azotetrazolate (1) was fully characterized through IR and NMR ( 1 H, 13 C, 31 P) spectroscopy as well as single-crystal X-ray diffraction. Both the 1 H and 13 C NMR spectra were in good agreement with the expected structure.…”

“…Tetraphenylphosphonium-5,5'-azotetrazolate (1) was fully characterized through IR and NMR ( 1 H, 13 C, 31 P) spectroscopy as well as single-crystal X-ray diffraction. Both the 1 H and 13 C NMR spectra were in good agreement with the expected structure. For example, the 1 H NMR spectrum showed a multiplet at δ 7.95 ppm for the phenyl hydrogens in para-position and a broad multiplet at δ 7.83-7.67 ppm can be assigned to the asymmetric N-C=N stretching vibration of the tetrazole ring, while a strong band at 724 cm −1 is characteristic for the asymmetric C-N=N stretching vibration of the azotetrazolate dianion [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].…”

Synthesis and Crystal Structures of New 5,5'-Azotetrazolates

“…Numerous crystal structures of 5,5'-azotetrazolate salts [3][4][5][6][7][8][11][12][13]16,20,21] have been reported, including a series of metal salts; specifically, alkali and alkaline earth metals [22,23], lanthanoids [24][25][26], Pb [27], Tl [28], Mn [29], Fe [30], Cu and Cd [31] form crystalline salts.…”