Synthesis and Reactivity of Zirconium and Hafnium Dihydroxophthalocyaninates
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HEMISTRY OF MACROCYCLIC AND METALLOCYCLIC COMPOUNDS
Synthesis and Reactivity of Zirconium and Hafnium Dihydroxophthalocyaninates V. Cherniia, *, I. Tretyakovaa, R. Selina, N. Fedosovaa, and V. Kovalskab aVernadskii
Institute of General and Inorganic Chemistry, National Academy of Sciences of Ukraine, Kyiv, 03680 Ukraine of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, 03143 Ukraine *e-mail: [email protected]
bInstitute
Received April 25, 2020; revised May 14, 2020; accepted May 27, 2020
Abstract—Two synthetic approaches for obtaining of zirconium and hafnium dihydroxophthalocyaninates (i.e. (a) that using the zirconium and hafnium alkoxides as the reactive precursors and (b) hydrolysis of zirconium and hafnium dichloridophthalocyaninates) were evaluated. Reactivity of zirconium and hafnium dihydroxophthalocyaninates in their exchange reactions with β-diketones and with decanoic acid was also studied; they were compared with those of zirconium and hafnium dichloridophthalocyaninates. The use of zirconium and hafnium dihydroxophthalocyaninates as the precursors in their reactions with acid-sensitive ligands, such as ketoesters, is found to be a more effective approach. Keywords: zirconium complexes, hafnium complexes, phthalocyanines, axial ligands, exchange reactions DOI: 10.1134/S0036023620100046
INTRODUCTION The high stability and wide range of optical and electrophysical properties of the zirconium and hafnium phthalocyanine complexes (PcZrL2, PcHfL2) [1–4], as well as the possibility of their modification through the coordinatively unsaturated central metal atom [5–11], makes them prospective for use as pigments and dyes, electrocatalysts [12], photoelectrocatalytic [13], electrochromic agents and other materials [14–17]. The main method of obtaining of zirconium and hafnium phthalocyaninates with non-planar ligands is the reaction of substitution of chlorine atoms in PcMCl2 (M = Zr, Hf) with β-diketonate [5], β-ketoester [4], carboxylate ligands [9]. The peculiarity of such reaction is the release of hydrogen chloride, which can adversely affect the reaction pathway and thus on the formation of the target products. For example, hydrogen chloride could initiate the hydrolysis of acid-sensitive starting compounds, in particular, β-ketoesters,
OH M N N N N N N
which in turn may lead to the formation of side-products and consequently to a decrease in the purity and yield of the target complexes. In similar reaction with phthalocyanine PcM(OH)2 as starting compounds, their interaction with β-dicarbonyles or carboxylic acids generates water, which slightly affects either the starting materials or products of the reactions. Thus, PcM(OH)2 are considered as the preferable starting compounds in ligand exchange reactions, but preparative methods for them have not been developed sufficiently and their reaction ability has been poorly studied. The purpose of this work is to optimize the PcM(OH)2 preparation methods (Fig. 1) and study of their reactivity with β-diketones, β-ketoester
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