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A novel method of the preparation of (hetero)aryl nitriles based on the fragmentation of the corresponding pentafluorophenylhydrazones is described. The synthesis is metal‐free, proceeds in neutral conditions with no need of protecting group application and provides most nitriles in moderately good yields. The synthesis was performed on ten pentafluorophenylhydrazones with different functional groups within the carbonyl part – the reaction was found to be partially substrate selective. The reaction prefers substrates with aromatic electron donating substituents on the carbonyl part of the hydrazone. The second reaction product, 2,3,5,6‐tetrafluoroaniline, can be easily separated by vacuum distillation. Although the reaction mechanism is yet to be ascertained, all synthetic and spectroscopic data suggest a radical reaction mechanism.

Activated enol ethers derived from methyl or ethyl acetoacetate/cyanoacetates or nitriles and pentane-2,4-dione react with pentafluorophenylhydrazine through the primary amino-group to afford pyrazoles bearing a preferred 5-amino-over 5-methyl-or 5-hydroxy-substituent in the resulting 4-substituted pyrazoles.

Twenty-one pentafluorphenylhydrazones have been analyzed by means of tandem mass spectrometry (ESI MS/MS) conditions to compare their fragmentations with those ones obtained from quantum-chemical calculations of the hydrazone moiety depending on the substitution from the aldehyde site. The hydrazone N-N bond is disrupted under such conditions, and these results are in accordance with the facts that an electron-rich particle, such as an anion and or radical in a solution, can cause this disruption and simultaneous defluorination in para-position of the hydrazone part of the molecule.

The convenient and multigram synthesis of a linear benzo[b]dithiophene (BDT) structure is proposed (dimethyl 3,7-diamino-4,8-bis((2-methoxy-2-oxoethyl)thio)benzo[1,2-b:4,5-b’]dithiophene-2,6-dicarboxylate). The starting materials are commercially available 2,3,5,6-tetrachloroterephthalonitrile and methyl 2-mercaptoacetate, which undergo aromatic substitution, followed by a cyclization reaction in basic conditions to form suitable BDT for potential optoelectronic applications.

The crystals, C11H4BrF5N2S, (I), 1-((4-bromothiophen-2-yl)methylene)-2-(perfluorophenyl)hydrazine and C12H6BrF5N2S, (II), 1-((4-bromo-5-methylthiophen-2-yl)methylene)-2-(perfluorophenyl)hydrazine are molecules with two rings and hydrazone part like a centre of the molecule. The compounds have been synthesized and characterized by elemental, spectroscopic (1H-NMR) analysis. The crystal structures of the solid phase were determined by single crystal X-ray diffraction method. They crystallize in the monoclinic space group with Z = 4 and Z = 2 molecules per unit-cell. The compound (I) crystallizes as a racemate in the centrosymmetric space group and the compound (II) crystallizes as a non-racemate in the non-centrosymmetric space group. The “absolute configuration and conformation for bond values” were derived from the anomalous dispersion (ad) for (II). The crystal structures are revealed diverse non-covalent interactions such as intra- and interhydrogen bonding, π-ring···π-ring, C-H···π-ring and they were investigated. The expected stereochemistry of hydrazones atoms C7, N2 and N1 were confirmed for (I) and (II). The hole molecule of the (I), and (II) possesses “a boat conformation” like a 6-membered ring. The results of the single crystal studies are reproduced with the help of Hirshfeld surface study and Gaussian software.