Germanium Phthalocyanine, GePc, and the Reduced Complexes SiPc(pyridine)<sub>2</sub> and GePc(pyridine)<sub>2</sub> Containing Antiaromatic π-Electron Circuits

Cissell, Julie A.; Vaid, Thomas P.; DiPasquale, and Antonio G.; Rheingold, Arnold L.

doi:10.1021/ic701248u

Cited by 69 publications

(89 citation statements)

References 10 publications

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“…The fivemembered ring B shows a very low aromaticity and it also becomes more aromatic when increasing the initial 6-31G basis set to 6-311++G(d,p), and the corresponding B3LYP-calculated NICS(1) zz parameter changes from − 4.9 to − 6.8 ppm. The relative aromaticity of ring subunits A1, B, and C, expressed by the NICS(1) zz parameter, is similar to earlier reported properties of these rings in free molecule of silicon phthalocyanine (compare NICS(0) and NICS(1) values in [76]) and magnesium phthalocyanine [77]. Interestingly, in germanium phthalocyanines [77], NICS(1) predicted the presence of anti-aromatic rings.…”

Section: Aromaticity Of Different Structural Fragments Of Znpc and Znsupporting

confidence: 85%

“…The relative aromaticity of ring subunits A1, B, and C, expressed by the NICS(1) zz parameter, is similar to earlier reported properties of these rings in free molecule of silicon phthalocyanine (compare NICS(0) and NICS(1) values in [76]) and magnesium phthalocyanine [77]. Interestingly, in germanium phthalocyanines [77], NICS(1) predicted the presence of anti-aromatic rings. In this molecule, ring B was the most, and ring C the least, anti-aromatic.…”

Section: Aromaticity Of Different Structural Fragments Of Znpc and Znsupporting

confidence: 85%

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Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

2017

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A theoretical investigation on the planarity of molecular structure of zinc phthalocyanine (ZnPc) and its aromaticity has been performed using B3LYP and M06-2X density functionals combined with selected Pople-type basis sets. The effect of the applied calculation method on the optimized structure of ZnPc and ZnPc•••H 2 O, both in the gas phase and in the polar solvent, was analyzed. To quantify the aromaticity of the ZnPc and ZnPc•••H 2 O complexes, both the geometric and magnetic criteria, i.e., Harmonic Oscillator Model of Aromaticity (HOMA) index and the nucleus-independent chemical shift (NICS) values at the centers or 1 Å above the centers of structural subunits, were calculated. The energies of highest energy occupied molecular orbital (HOMO) and lowest energy unoccupied molecular orbital (LUMO) and energy gaps were also estimated. The results show that the free ZnPC molecule is flat in the gas phase and nonplanar in the polar environments (DMSO and water). ZnPC•••H 2 O is nonpolar in the gas phase and polar solvent which is in agreement with recent X-ray reports. Both HOMA and NICS indexes indicate the presence of highly aromatic macrocycle and benzene rings while these parameters for pyrrolic ring are significantly smaller than in free pyrrole. The presence of polar solvents practically does not change aromaticity of the ring subunits of the studied compounds.

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Section: Aromaticity Of Different Structural Fragments Of Znpc and Znsupporting

confidence: 85%

Section: Aromaticity Of Different Structural Fragments Of Znpc and Znsupporting

confidence: 85%

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

2017

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“…15 Both sets of data are shifted significantly upfield from the region where Pc 2− ligand resonances would be expectedfor example, the 1 H NMR spectrum of 1 has signals at δ = 9.06 and 8.03, and the 1 H NMR spectrum for a zirconium(IV) phthalocyanine with an axial dibenzoylmethane ligand shows ring proton signals at δ = 9.37 and 8.30. To the best of our knowledge, there is only one previous example where a di-reduced phthalocyanine species has been characterized by NMR spectroscopy: PcGe( py) 2 , with ring-proton resonances at δ = 5.1 and 4.3.…”

Section: Introductionmentioning

confidence: 98%

“…15,16 The quadrants of the Pc 4− ligand adopt a corrugated wave-type arrangement (Fig. 15,45 Analogous reactions using NaCp also generated Pc 3− and Pc 4− containing complexes, but the reactions were much less clean, with several other (unidentified) products forming simultaneously (see ESI †). The Zr(IV) centre is positioned 0.965 Å above the Pc-plane vs. the 1.067 Å in 1.…”

Section: Introductionmentioning

confidence: 99%

Reducing zirconium(iv) phthalocyanines and the structure of a Pc⁴⁻Zr complex

et al. 2015

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The synthesis and characterization of the ring-unsubstituted zirconium phthalocyanine PcZrCl2 (; Pc(x-) = phthalocyaninato(x-)) and its reduction products are described. X-ray analysis of (crystallized from hot 1-chloronaphthalene) reveals that is a chloride-bridged dimer [PcZrCl]2(μ-Cl)2 in the solid-state; was also characterized by UV-vis/MCD spectroscopy and cyclic voltammetry, which indicated reduction potentials at -0.55, -0.95 and -1.28 V. Although attempts to access these Pc-ring reduced species with KC8 led to mixtures of reduced products due to the insolubility of both starting materials, one equivalent of the reducing agent KEt3BH reacted with to generate Pc(3-)-containing species, as indicated by visible Q-band spectral changes (from λmax = 686 for to 589/611 nm), a single ESR peak (g = 2.001) and paramagnetically shifted (1)H NMR resonances consistent with the presence of a Pc-radical anion. Addition of two equivalents of KEt3BH to generated Pc(4-)-containing species, confirmed by a shift in λmax to 522 nm and upfield-shifted (1)H NMR peaks relative to . Reaction of with one and two equivalents of LiCp* did not generate Cp*-substituted products but also effected reduction to analogous Pc(3-) and Pc(4-) species. This latter material, the air-sensitive ring di-reduced "ate"-complex Pc(4-)Zr(LiCl)1.5(DME)3, of the form [LiCl(DME)4]0.5[Pc(4-)ZrClLi(DME)] was structurally characterized, illustrating partial bond localization in the Pc(4-) ring, which also adopts a saddle-shape vs. the more typical dome-configuration found in . This represents a rare example of an isolated and structurally characterized Pc(4-) complex.

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“…In general, two‐electron‐ and one‐electron‐reduced porphyrins (20π and 19π porphyrins, respectively) are extremely unstable under atmospheric conditions because of their high‐energy highest occupied molecular orbital (HOMO) and singly occupied molecular orbital (SOMO), respectively . Several approaches have been proposed to isolate 20π and 19π porphyrins in neutral forms, which basically rely on the concept of lowering the HOMO or SOMO energy levels . However, most of the reported neutral 20π and 19π porphyrins are highly distorted and/or still air‐sensitive.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and properties of redox‐switchable zinc complexes of 10,15,20‐triaryl‐15‐aza‐5‐oxaporphyrin

Sudoh

Furukawa

Nakano

et al. 2018

Heteroatom Chemistry

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The synthesis, aromaticity, and optical and electrochemical properties of zinc(II) complexes of 10,15,20‐triaryl‐15‐aza‐5‐oxaporphyrin (TriAAOP) were investigated. Metal‐templated cyclization of a zinc(II) 1,19‐dichloro‐5,10,15‐triaryl‐10‐azatetrapyrrin complex with an oxygen source afforded 20π TriAAOP in the neutral form. Oxidation of 20π TriAAOP with silver (I) hexafluorophosphate generated the 19π radical cation or 18π dication depending on the content of oxidant used. The interconversion between the three oxidation states (18π, 19π, and 20π) resulted in distinct changes in the aromaticity and optical properties of the 15‐aza‐5‐oxaporphyrin π‐system. Nuclear magnetic resonance spectroscopy of 20π TriAAOP revealed its antiaromatic character, whereas that of the 18π TriAAOP dication showed its aromatic character. The combined effect of the two meso‐heteroatoms was directly reflected in the redox properties of the porphyrin ring; TriAAOP was reduced more easily and more difficult to oxidize than the zinc(II) complex of 5,10,15,20‐tetraaryl‐5,15‐diaz‐aporphyrin (TADAP). In the ultraviolet‐visible‐near–infrared spectra of the materials, the lowest‐energy electronic excitations of the 19π and 18π TriAAOP derivatives were considerably red‐shifted compared with those of the isoelectronic TADAP derivatives. Based on the results of density functional theory calculations, it was concluded that the observed differences between TriAAOP and TADAP would arise from the high electronegativity of oxygen; specific frontier orbitals of the TriAAOP π‐systems were energetically stabilized relative to those of the TADAP π‐system. The present findings corroborate that the meso‐modification of a porphyrin rings with different kinds of heteroatoms is a promising strategy to fine tune their light‐response properties that are switchable by reversible single electron transfer processes.

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Germanium Phthalocyanine, GePc, and the Reduced Complexes SiPc(pyridine)₂ and GePc(pyridine)₂ Containing Antiaromatic π-Electron Circuits

Cited by 69 publications

References 10 publications

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

Reducing zirconium(iv) phthalocyanines and the structure of a Pc⁴⁻Zr complex

Synthesis and properties of redox‐switchable zinc complexes of 10,15,20‐triaryl‐15‐aza‐5‐oxaporphyrin

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Germanium Phthalocyanine, GePc, and the Reduced Complexes SiPc(pyridine)2 and GePc(pyridine)2 Containing Antiaromatic π-Electron Circuits

Cited by 69 publications

References 10 publications

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

Reducing zirconium(iv) phthalocyanines and the structure of a Pc4−Zr complex

Synthesis and properties of redox‐switchable zinc complexes of 10,15,20‐triaryl‐15‐aza‐5‐oxaporphyrin

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Germanium Phthalocyanine, GePc, and the Reduced Complexes SiPc(pyridine)₂ and GePc(pyridine)₂ Containing Antiaromatic π-Electron Circuits

Reducing zirconium(iv) phthalocyanines and the structure of a Pc⁴⁻Zr complex