Unusual shift of a nitro group in a phenylhydrazo-β-diketone

Abstract

A novel para to meta shift of a nitro group at the phenyl ring of 3-(2-hydroxy-4-nitrophenylhydrazo)pentane-2,4-dione (H₂L¹, 1), with formation of the new 3-(2-hydroxy-3,5-dinitrophenylhydrazo)pentane-2,4-dione (H₂L², 2), occurs upon nitration of 1 with an equimolar amount of NaNO₂, under basic conditions. 2 acts as a polydentate ligand for the synthesis of the polymeric potassium [K(μ₅-HL²)]_n (3) and monomeric nickel(II) [Ni(H₂O)₃(L²)]·H₂O (4) compounds. They have been fully characterized, including single crystal X-ray analysis, and the complexes feature metal–organic (in 3) or supramolecular (in 4) 3D networks. The topological analysis of 3 reveals a uninodal 5-connected underlying net with the point symbol of (4⁶.6⁴) and a very rare 5/4/t5 topology, which had not yet been observed in coordination polymers.