Abundant Polymorphism in a System with Multiple Hydrogen-Bonding Opportunities:  Oxalyl Dihydrazide

Abstract

To date, only one crystal structure has been reported in the literature for oxalyl dihydrazide [H(2)N.NH.CO.CO.NH.NH(2)]. In the present paper, we report the discovery of four new polymorphs of oxalyl dihydrazide, obtained by crystallization from solution under different conditions, including the use of different crystallization solvents. All polymorphs have the trans-trans-trans conformation of the N-N-C-C-N-N backbone, but the positions of the hydrogen atoms of the NH(2) groups relative to this backbone differ between the different polymorphs through variation of the torsion angle around each NH-NH(2) bond. The different polymorphs display a range of different hydrogen-bonding arrangements, constructed from different types of hydrogen-bonded array. The existence of several different potential hydrogen-bond donor and hydrogen-bond acceptor groups in the oxalyl dihydrazide molecule, together with the fact that the N-H bonds of the NH(2) groups adopt different orientations with respect to the molecular plane, leads to several possible geometric permutations for hydrogen-bonding arrangements in the solid state. It would not be surprising if even more polymorphs of oxalyl dihydrazide are discovered in the future.

Polymorphism and Phase Behaviors of 2-(Phenylamino)nicotinic Acid

“…19,20 In 2005, four new polymorphs were reported for oxalyl dihydrazide (ODH). 21 The system described in this report is the newest addition to the "elite club" of organics with four or more polymorphs.…”

Discovery of High-Pressure Polymorphs for a Typical Polymorphic System: Oxalyl Dihydrazide

“…Four forms of ODH, α, γ, δ, and ε, were prepared as the methods described by D. M. Harris. 26 High-quality crystals were chosen after detailed examination under an optical microscope and gently ground to obtain powders with a size of approximately several micrometers. The purity of the crystal was confirmed by XRD patterns, which are shown in Figure S1 (Supporting Information, SI).…”

“…The five polymorphs have been reported in the literature, namely, α, β, γ, δ, and ε. 26 The crystal structures of the five polymorphs are all monoclinic with space group P2 1 /c, and the crystallographic data of ODH polymorphs are summarized in Table 1. 26 In all polymorphs, the N−N−C− C−N−N backbone of the molecule is planar and adopts the trans−trans−trans conformation.…”

“…26 The crystal structures of the five polymorphs are all monoclinic with space group P2 1 /c, and the crystallographic data of ODH polymorphs are summarized in Table 1. 26 In all polymorphs, the N−N−C− C−N−N backbone of the molecule is planar and adopts the trans−trans−trans conformation. The oxygen atoms of the OC groups and the hydrogen atoms of the NH groups lie within this plane.…”

Crystallization of the polymorphs of succinic acid via sublimation at different temperatures in the presence or absence of water and isopropanol vapor

“…1). In general, the precipitation of various polymorphs can be induced by varying crystallization conditions, such as solvents or additives [9,10]. However, in the case of succinic acid, there have been no reports to date of the preparation of a succinic acid by solution crystallization.…”