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Routes to New hafnium(IV) Tetraaryl Porphyrins and Crystal Structures of Unusual Phosphate-, Sulfate-, and Peroxide-Bridged Dimers

Alexander Falber, Louis Todaro, Israel Goldberg, Michael V Favilla, Charles Michael Drain

Inorg Chem. 2008 Jan 21;47(2):454-67.

PMID: 18088113

Abstract:

New routes for the synthesis of mono tetraaryl porphyrinato hafnium(IV) complexes, Hf(IV)Por(L)(2), are reported, where the secondary ligands, L, are determined by the method of purification. These synthetic routes cater to the solubility of the macrocycles and provide access to Hf(IV) complexes of meso tetraaryl porphyrins bearing diverse functional groups such as phenyl, tolyl, pyridyl, pentafluorophenyl, and carboxyphenyl. The latter three derivatives significantly expand the repertoire of hafnium porphyrinates. One route refluxes the porphyrin with HfCl(4) in 1-chloronaphthalene or in a mixed solvent of 1-chloronaphthalene and o-cresol. A second, solventless method is also reported wherein the porphyrin is mixed with Hf(cp)(2)Cl(2) and heated to give the metalated porphyrin in good yields. Simultaneous purification and formation of stable porphyrinato hafnium(IV) diacetate complexes, Hf(Por)OAc(2), is accomplished by elution over silica gel using 3-5% acetic acid in the eluent. Exchange of the acetate ligands for other oxo-bearing ligands can be nearly quantitative, such as p-aminobenzoate (PABA), pentanoate (pent), or octanoate (oct). Notably, we find that two to three of a variety of small multitopic dianions such as peroxo (O(2)(-2)), SO(4)(-2), and HPO(4)(-2) serve to bridge between two Hf(Por) moieties to form stable dimers. The crystal structures of this library of Hf(Por) complexes are reported, and we note that careful analysis of crystallography data reveals (Por)Hf(micro-eta(2)-O(2))(2)Hf(Por) rather than four bridging oxo or hydroxy ions.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP15823435 Hafnium(IV) sulfate Hafnium(IV) sulfate 15823-43-5 Price
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