Synthesis, Crystal Structure, and Vibrational Spectra of the Anhydrous Lithium Dicyanamide Li[N(CN)₂]

Abstract

Crystals of Li[N(CN)2] were synthesized from a metathesis reaction of stoichiometric amounts of aqueous solutions of Na[N(CN)2] and Li2[SO4] followed by subsequent treatment with ethanol and evaporation of the filtered‐off solution at 80 °C under normal atmospheric conditions. The single crystals of the title compound are transparent, colorless, and extremly hygroscopic. X‐ray structure analysis showed that Li[N(CN)2] crystallizes in the monoclinic space group P2/c with the cell parameters a = 530.79(8) pm, b = 524.89(9) pm, c = 1149.77(17) pm, β = 101.551(7)°, and Z = 4. The crystal structure contains Li+ cations in both tetrahedral and octahedral nitrogen coordination of the boomerang‐shaped [N≡C–N–C≡N]– anions. The vibrational spectra of Li[N(CN)2] are reported as well, together with ab initio calculations for geometry and harmonic frequencies of the free dicyanamide anion.

Synthesis and Characterization of the New Dicyanamide LiCs2[N(CN)2]3

“…The angles of the [dca] anion are also typically found for such a moiety with ∡(N1-C-N2) = 172.1° and ∡(C-N1-C) = 119.8° ( Figure 1, Table 1). [9]. These octahedra are connected with each other by sharing three [N(CN)2] − and they are bonded by the terminal nitrogen atoms.…”

“…The coordination sphere is completed by three terminal nitrogen atoms in the layers below or above the Cs + with d(Cs- The thermal ellipsoids correspond to 90% probability using the refined ADPs. [9]. These octahedra are connected with each other by sharing three [N(CN) 2 ] − and they are bonded by the terminal nitrogen atoms.…”

“…Moreover, some dicyanamides show promise as water-oxidation catalysts [6], whilst Li [dca] has been suggested as a potential lithium-ion battery material [7]. In total, there is an enormous variety of pseudo-binary dicyanamide compounds available with examples known for ammonium [8], alkali metals [9][10][11][12], alkaline-earth metals [13], transition metals [4][5][6][14][15][16][17][18][19], and rare-earth metals [20][21][22]. Additionally, a number of pseudo-ternary dicyanamides has also been reported with KCs[dca] 2 [23] [25].…”

Syntheses and Characterization of Two Dicyanamide Compounds Containing Monovalent Cations: Hg2[N(CN)2]2 and Tl[N(CN)2]

“…After filtering to remove the silver halides, the product can then be crystallized by simply evaporating water. Binary dicyanamide compounds are known for ammonium [4], alkali metals [5][6][7][8] (except Fr), alkaline-earth metals [9] (except Be and Ra), transition metals (Cr-Zn, except Fe) [10][11][12][13][14][15][16], and rare-earth metals (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb) [17][18][19]. Ternary compounds, such as KCs[dca] 2 [20], LiK[dca] 2 [21], LiRb[dca] 2 [21], NaRb 2 [dca] [22], and LiCs 2 [dca] 3 [23] are also known.…”

About alkali metal dicyanamides: syntheses, single-crystal structure determination, DSC/TG and vibrational spectra of KCs[N(CN)2]2 and NaRb2[N(CN)2]3 · H2O

“…The structural chemistry of alkali dicyanamides M[N(CN) 2 ] (from now on called 'M[dca]') was explored over the last one or two decades [1][2][3][4][5] and the structure of Li[dca] was determined by us just recently [6]. The only pseudoternary alkali [dca] compound reported previously was NaCs 2 [dca] 3 [2].…”