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The Redox‐Active Chromium Phthalocyanine System: Isolation of Five Oxidation States from Pc 4− Cr I to Pc 2− Cr III
Author(s) -
Zhou Wen,
Thompson John R.,
Leznoff Clifford C.,
Leznoff Daniel B.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201604155
Subject(s) - phthalocyanine , chemistry , chromium , redox , octahedron , ring (chemistry) , halide , metal , crystallography , monomer , stereochemistry , medicinal chemistry , inorganic chemistry , crystal structure , polymer , organic chemistry
The preparation and structural characterization of a series of chromium phthalocyanine complexes with multiple metal and ring oxidation states were achieved using PcCr II ( 1 ) (Pc=phthalocyanine) or PcCr II (THF) 2 ( 1⋅THF 2 ) as starting materials. The reaction of soluble 1⋅THF 2 with Br 2 or I 2 gave the PcCr III halide complexes PcCrX(THF) (X=I/I 3 , Br; 3 , 4 , respectively). Treatment of 1 with 0.5 equivalent of PhIO or air generated the dinuclear [PcCr(THF)] 2 (μ‐O) ( 5 ), whereas the addition of one equivalent of AgSbF 6 to 1 resulted in oxidation to THF‐solvated octahedral [PcCr III (THF) 2 ]SbF 6 ( 6 ). The reduction of 1 with three sequential equivalents of KEt 3 BH resulted in the isolation of [K(DME) 4 ][Pc 3− Cr II ] ( 7 ), [K(DME) 4 ] 2 [Pc 4− Cr II ] ( 8 ) and [K 6 (DME) 4 ][Pc 4− Cr I ] 2 ( 9 ), respectively. The reduced products are deep purple in colour, with visible absorption maxima between 500–580 nm. The ring‐reduced complexes 7 and 8 are monomeric, whereas 9 is a 1D chain of dinuclear [PcCr] 2 units with intercalated K + cations and supported by Cr−Cr interactions of 2.988(2) Å. Addition of four equivalents of KC 8 resulted in the demetallated product PcK 2 (DME) 4 ( 10 ), which has a 1D chain structure. The isolation and structural characterization of new PcCr complexes spanning five oxidation states, including rare examples of crystalline reduced Pc‐ring species emphasizes the broad redox activity and stability of phthalocyanine‐based complexes.