Crystal Structure of 1,2-Bis(cyanoimino)-3-triethylammonio-cyclopropenylide

Johannes BECK, Petra KRIEGER-BECK
2006 Analytical Sciences X-ray Structure Analysis Online  
Tris(cyanoimino)deltate 3 represents a pseudo chalcogenide derivative of the C3 oxocarbon anion C3O3 2-. Its composition, C6N6 2-, makes it a candidate for exploring compounds composed only of carbon and nitrogen. Its synthesis has been described 1 starting from tetrachlorocyclopropene 1, which is converted by cyanamide in the presence of triethylamine to the zwitterionic 1,2-bis(cyanoimino)-3-triethylammoniocyclopropenylide 2. The triethylammonium group can be substituted by a third cyanoamide
more » ... a third cyanoamide anion which yields 3 (Scheme 1). On repeating this synthetic procedure, we obtained amber crystals of 2 from methanol. The spectroscopic data were in line with those reported 1 ( 13 C-NMR, mass spectrum). The X-ray analysis results are given in Tables 1 -3. All H atoms were located in difference Fourier synthesis and refined with isotropic displacement parameters. The title molecule consists of a three-membered C3 ring bearing two cyanoimino groups and a triethylammonium group (Fig. 1 ). The triangular ring has two short bonds (C1-C2 = 1.36 and C1-C3 = 1.37 Å) and one longer bond (C2-C3 = 1.44 Å), indicating that the double bond of the cyclopropene ring is .mainly delocalized between C1-C2 and C1-C3. The two cyanoimino groups deviate only slightly from linearity (mean angle at C10 and C11 = 173˚). The coordination around the ammonium N atom N1 is almost regular tetrahedral with C-N1-C angles deviating by not more than 4˚ from 109.5˚. The atoms of the two cyanoimino groups, the carbon atoms of the C3 ring and N1 are all located in one plane. The largest deviations from the least-squares plane through all ten atoms are observed for N4 with 0.05 Å and for N5 with 0.06 Å. The NEt3 group is tilted against this plane, which is shown in Fig. 1 in a view along the plane down the C1-N1 axis. In the crystal, the molecules are stacked slightly inclined along the a-axis (Fig. 2) . The molecular planes are parallel and the molecules are arranged in an alternating head-to-tail fashion with the bulky NEt3 groups pointing out of the stack. The x239 ANALYTICAL SCIENCES 2006, VOL. 22 X-ray Structure Analysis Online The title compound, C11H15N5, crystallizes in the monoclinic space group P21/n with cell parameters a = 6.9935(1), b = 14.4416(3), c = 11.5160(2)Å, β = 93.608(1)˚. The zwitterionic molecular structure consists of a cyclopropene ring substituted by two cyanoimino and a triethylammonium group. The two NCN groups, the C3 ring and the N atom of the NEt3 group are coplanar. In the crystal, the molecules are stacked perpendicular to these planes. Scheme 1 Reaction sequence for the synthesis and chemical diagram for the title compound 2. Table 1 Crystal and experimental data Formula: C11H15N5 Formula weight: 217.27 Crystal system: monoclinic Space group: P21/n Z = 4 a = 6.9935(1)Å b = 14.4416(3)Å = 93.608 (1)c = 11.5160(2)Å V = 1160.8(4)Å 3 Dx = 1.243 g/cm 3 Crystal dimensions (mm) = 0.70 × 0.2 × 0.2 R = 0.037 for 2049 Fo > 4 (Fo) Rw = 0.099 range for data collection: 3.24 to 27.50G oodness-of-fit = 1.017 ( ρ)max = 0.18 eÅ -3 ( ρ)min = -0.14 eÅ -3
doi:10.2116/analscix.22.x239 fatcat:gpzmhnugpbbpjf4zpmd5e6pknu