Competitive H-bonding synthons in organic hydrazides

Abstract

A theoretical, statistical and crystallographic analysis of the H-bonding patterns in organic\ud monohydrazides is presented. The theoretical analysis has shown that the conformation of the\ud hydrazido group with the two amino H atoms staggered with respect to the amide bond is energetically\ud more favoured. Assuming this conformation, four intermolecular H-bonding patterns can be\ud reasonably foreseen, two forming chains, C(4) and C2\ud 2(8), and two forming rings, R2\ud 2(10) or R2\ud 2(6).\ud The frequency of occurrence of the four patterns in the set of crystal structures of hydrazides retrieved\ud from CSD was evaluated. In particular, it was found that the four motifs are present in 79% of the total\ud number of crystal structures of hydrazides found in CSD. Finally, the crystal structures of four new\ud benzohydrazides having additional H-bonding donor or acceptor groups in the para position are\ud presented and discussed with reference to the H-bonding patterns

Reactions of the Tetraalkyldigallium Compound R2Ga–GaR2 [R = CH(SiMe3)2] with Acidic Reagents, Retention vs. Cleavage of the Ga–Ga Bond and Formation of Supramolecular Aggregates via Hydrogen Bonding

“…Two five‐membered GaCN 2 O heterocycles result which are annulated via the central N–N bond. The N–N bond lengths (143.1 pm on average) are in the lower range of N–N bonds in hydrazine derivatives,12 but correspond well to values of dicarbonyl hydrazides 20. Ga–O (194.6 pm) and Ga–N distances (201.6 pm on average) are in normal ranges.…”

“…The NH 2 groups adopt cis ‐positions and are on the same side of the molecules. The N–N distances (146.7 pm on average) correspond to standard values of N–N single bonds in acid hydrazides 12. C=N (130.1 pm) and C–O bond lengths (129.6 pm) are in accordance with π‐delocalization in the O–C=N group 13.…”

Supramolecular synthons in fluorinated and nitrogen-rich ortho-diaminotriazoles

“…As a prosecution of our studies on the synthesis and H bonding patterns of heterocycles and nitrogen-rich compounds [10,11], we present in this article an investigation on 3,4-diamino-1,2,4-triazoles (Scheme 1). The synthesis of these heterocycles has not been described comprehensively in the literature; yet, they are building blocks of nitrogen-rich, aromatic fused-ring systems potentially interesting in organic electronics.…”

Polar crystals in imines of 4-hydroxybenzohydrazide: a comparison between racemic and enantiomorphic crystals

“…Amide-like chains running along a are formed between molecules related by translation, as also suggested by the length of the a axis. 5 However, as is evident from Fig. 5(a), the two chains running along a, formed by independent molecules of the same type, do simulate a pseudo-centrosymmetric arrangement.…”

“…The vector is basically oriented transverse with respect to the long molecular axis of the molecule (transverse chromophore 3b ), since the resonance forms of the amide group are the predominant contribution. 5 In fact, the angle between m g and the long molecular vector (LM) joining the imino nitrogen with the hydroxy oxygen is ca. 75u for both forms of 1ort.…”