The molecular and crystal structure of hydrogen cyanide tetramer (diaminomaleonitrile)

Abstract

A three-dimensional crystal structure analysis of hydrogen cyanide tetramer has led to a location of all atoms with average standard deviations of 0.0025 A for carbon and nitrogen atoms and 0.04 A for hydrogens. The diaminomaleonitrile structure is proved. In its crystal setting the molecule has no symmetry. The two amino groups have different configurations, one being planar and one tetrahedral while both being involved in intermolecular N-H • • • 1W hydrogen bonds. An analysis is made of the anisotropic nature of the atomic thermal vibrations. Molecular orbital calculations have been made for this molecule and for tetracyanoethylene leading to z bond orders for all bonds. Order/length relationships for the carbon-carbon bonds are discussed in some detail.

Structure of bis(diiminosuccinonitrilo)nickel(II), [Ni(C4H2N4)2]

“…The bond lengths of the disn ligand are comparable to those found in Pt(disn) 2 (Lauher & Ibers, 1975) and Co(disn)2(CN).2H20 (Peng, Wang, Wang, Chung, Le Page & Gabe, 1981) (Table 2) Penfold & Ibers ( 1981) Lipscomb (1975) (1961 differences between the anion ligand in the complex and the free ligand diaminomaleonitrile (damn) (Penfold & Lipscomb, 1961) involve N(1)-C(1) and C(1)-C(2), with N(1)-C(1) much shorter (1.330A) and C(1)-C(2) much longer (1.403 A) in the complex than in the free ligand (1.392, 1.363 A). This confirms the delocalization of z~ electrons over the ligand moiety upon complexation.…”

HCN polymers characterized by solid state NMR: Chains and sheets formed in the neat liquid

“…4͑b͒ and 5͑b͔͒ due to the splittings that result from the asymmetric environment of the molecule in the crystal. [28][29][30] Furthermore, washing our samples with hot isopropanol, which is a good solvent for DAMN, removes all of the narrow signals, leaving some residual nitrile and all of the broad signals ͑spectrum not shown͒. On the other hand, DAMN is not formed in the presence of hydroquinone ͓Figs.…”

Molecular and Valence Structures of Complexes of Cyclo-Octatetraene with Iron Tricarbonyl

“…5 The geometry of COT is thus apparently dominated by the planar ethylene-like residues in the molecule and the tub-like conformation of COT is retained in the Ag(GOT)+ complex. 6 The failure of COT to show aromatic character receives its most natural rationalization from molecular orbital (MO) theory which yields, in the one electron MO approximation, two unpaired electrons if the molecule has planar D8h symmetry or the non-planar crown D4d symmetry.…”