Synthesis, vibrational spectra and single-crystal structure determination of lithium tricyanomethanide Li[C(CN)3]

Abstract

Abstract The long-elusive structure of lithium tricyanomethanide Li[C(CN)3] has been determined on the basis of material synthesized via a metathesis reaction of Ag[C(CN)3] with LiCl in water driven by AgCl precipitation and subsequently recrystallization from methanol. Li[C(CN)3] crystallizes in the non-centrosymmetric orthorhombic space group Ima2 with the unit-cell parameters a=751.06(4), b=1059.75(6) and c=563.27(3) pm adopting a unique structure with planar [C(CN)3]− anions exhibiting nearly ideal trigonal planar D 3 h symmetry. The Li+ cations are coordinated by five independent tricyanomethanide anions forming a distorted square pyramid with Li–N distances between 202 and 249 pm. The vibrational frequencies were also determined and along with other properties of Li[C(CN)3] compared with those of related compounds.