The crystal structure of ammonium tricyanomethide, NH₄C(CN)₃

Abstract

The structure of ammonium tricyanomethide, NH4C(CN)3 has been determined by X-ray singlecrystal diffraction techniques. The crystals are monoclinic in the space group P2~/c. The unit-cell constants are : a --9-055 + 0-007, b --3.87 _+ 0.01, c = 17.325 +_ 0.014 A, fl = 104-6 _+ 0.2 °. Atomic and thermal vibrational coordinates were refined by isotropic least-squares methods. The C(CN)~-ion is slightly nonplanar with 3m (C3v) symmetry indicating a concentration of anion charge on the central carbon atom. The three C-C distances were found to be 1.40 _+ 0.01 I and the C-N distances were 1-15 _+ 0.01A.

The structure of silver dicyanonitromethanide, AgC(CN)2NO2

“…Thevariety of small distortions from mm2 symmetry shows that the geometry of this anion is measurably sensitive to its environment. This phenomenon has already been observed in the C(CN)s ion, which shows different deviations from planarity in the ammonium, sodium, and potassium salts (Desiderato & Sass, 1965;Andersen, Klewe & Thorn, 1967;Andersen, 1967;Witt & Brittod, 1971), in the C(CN) (NO2)~-ion, which shows different C-NO2 torsion angles in the rubidium ~ind potassium salts (Bjornstad & Klewe, 1972;, and in the C(NO2)~" ion, which shows different C-NO2 torsion angles in the crystallographically discrete ions in the hydrazinium salt and in the potassium salt (Dickens, 1970;Golovina & Atovmyan, 1967). Klewe (private communication) has determined the structure of KC(CN)2NO2.…”

Tetramethylammonium hexacyanotrimethylenecyclopropanide: crystal structure of antiferromagnetic phase II and paramagnetic phase I

“…Coulombic interactions between the radical anions and [(CH3)4N] + cations result in C(lc)...N(3)= 3.400 (8) and C(3c)...N(2)= 3.371 (7)/~, as shortest contacts, where c represents a cation atom. All other cation-radical contacts are longer than 3.5 A. Coulombic C...N interactions between NH~-and CN-of 3.04/~ are reported in NH4CN (Lely & Bijvoet, 1944), and N...N interactions between NH~-and C(CN) 3 of 2.93-3.17/~ in NHaC(CN) 3 (Desiderato & Sass, 1965).…”

The Search for Tricyanomethane (Cyanoform)

“…Indeed, we have obtained a crystalline hydrate with properties similar to but not identical with those described earlier by others, [1][2][3] but it has turned out, however, to be hydronium tricyanomethanide (3) with planar tricyanomethanide anions identical with those observed previously in other crystalline tricyanomethanide salts. [4][5][6][7][8] Only in the gas phase at a pressure of less than 40 mTorr has tricyanomethane been identified by Bak and Svanhout from its microwave spectrum. [9] History The tricyanomethane story begins in 1896 when Schmidtmann added dilute sulfuric acid to an aqueous solution of sodium tricyanomethanide.…”