1H NMR and EPR studies of the electronic structure of low-spin iron(III) isocyanide mesotetraphenylchlorin complexes: a (dxz,dyz)4(dxy)1 configuration from 293 to 4 K †

Simonneaux, Gérard; Kobeissi, Marwan

doi:10.1039/b100925g

Cited by 18 publications

(35 citation statements)

References 47 publications

(22 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, for [Fe(TPC)(CN-t-Bu) 2 ]-CF 3 SO 3 , where Σg 2 ) 13.1 is much lower, a considerable amount of orbital angular momentum is quenched in this complex according to a (d xz , d yz ) 4 (d xy ) 1 ground state. 12 This interpretation is also supported by a recent EPR results on [Fe(TPC)(Im) 2 ]Cl reported by Walker et al showing that the highest g value is g z . 22…”

Section: Resultssupporting

confidence: 75%

Electronic Structure of Iron Chlorins: Characterization of Bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(III)triflate and Bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(II)

2003

Self Cite

View full text Add to dashboard Cite

The synthesis and characterization of the two iron chlorin complexes [Fe(III)(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) and Fe(II)(TPC)[(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2))](2) (2) are reported. The crystal structure of complex 1 has been determined. The X-ray structure shows that the porphyrinate rings are weakly distorted. The metal-nitrogen distances to the reduced pyrrole N(4), 2.034(4) A, and to the pyrrole trans to it N(2), 2.012(4) A, are longer than the distances to the two remaining nitrogens [N(1), 1.996(4) A, and N(3), 1.984(4) A], leading to a core-hole expansion of the macrocycle due to the reduced pyrrole. The (1)H NMR isotropic shifts at 20 degrees C of the different pyrrole protons of 1 varied from -0.8 to -48.3 ppm according to bis-ligated complexes of low-spin ferric chlorins. The EPR spectrum of [Fe(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) in solution is rhombic and gives the principal g values g(1) = 2.70, g(2) = 2.33, and g(3) = 1.61 (Sigmag(2) = 15.3). These spectroscopic observations are indicative of a metal-based electron in the d(pi) orbital for the [Fe(TPC)(NH(2)CH(CO(2)CH(3))(CH(CH(3))(2)))(2)]CF(3)SO(3) (1) complex with a (d(xy))(2)(d(xz)d(yz))(3) ground state at any temperature. The X-ray structure of the ferrous complex 2 also shows that the porphyrinate rings are weakly distorted. The metal-nitrogen distances to the reduced pyrrole N(4), 1.991(5) A, and to the pyrrole trans to it N(2), 2.005(6) A, are slightly different from the distances to the two remaining nitrogens [N(1), 1.988(5) A, and N(3), 2.015(5) A], leading to a core-hole expansion of the macrocycle due to the reduced pyrrole.

show abstract

Section: Resultssupporting

confidence: 75%

Electronic Structure of Iron Chlorins: Characterization of Bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(III)triflate and Bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(II)

2003

Self Cite

View full text Add to dashboard Cite

show abstract

“…Since II is supposed to be quite similar to alkyl or aryl isocyanide (R-NC) in its electronic structure, the (d xz , d yz ) 4 (d xy ) 1 ground state is greatly stabilized, as in the case of bis(R-NC) complexes; all the bis(R-NC) complexes reported previously show a very pure (d xz , d yz ) 4 (d xy ) 1 ground state due to the weak σ-donating and fairly strong π-accepting ability. 3,4,8, 35,36 Weak Hydrogen Bonding between Coordinated Cyanide and CDCl 3 or CD 2 Cl 2 . We have mentioned that the …”

Section: Ground-state Electron Configuration Of [Fe(et-tpp)-(cn) 2 ] mentioning

confidence: 99%

Effects of Solvents on the Electron Configurations of the Low-Spin Dicyano[meso-tetrakis(2,4,6-triethylphenyl)porphyrinato]iron(III) Complex: Importance of the C−H···N Weak Hydrogen Bonding

Ikezaki

Nakamura

2002

Inorg. Chem.

View full text Add to dashboard Cite

There are two types of electron configurations, (d(xy))(2)(d(xz), d(yz))(3) and (d(xz), d(yz))(4)(d(xy))(1), in low-spin iron(III) porphyrin complexes. To reveal the solvent effects on the ground-state electron configurations, we have examined the (13)C- and (1)H-NMR spectra of low-spin dicyano[meso-tetrakis(2,4,6-triethylphenyl)porphyrinato]ferrate(III) in a variety of solvents, including protic, dipolar aprotic, and nonpolar solvents. On the basis of the NMR study, we have reached the following conclusions: (i) the complex adopts the ground state with the (d(xz), d(yz))(4)(d(xy))(1) electron configuration, the (d(xz), d(yz))(4)(d(xy)())(1) ground state, in methanol, because the d(pi) orbitals are stabilized due to the O-H...N hydrogen bonding between the coordinated cyanide and methanol; (ii) the complex also exhibits the (d(xz), d(yz))(4)(d(xy))(1) ground state in nonpolar solvents, such as chloroform and dichloromethane, which is ascribed to the stabilization of the d(pi) orbitals due to the C-H...N weak hydrogen bonding between the coordinated cyanide and the solvent molecules; (iii) the complex favors the (d(xz), d(yz))(4)(d(xy))(1) ground state in dipolar aprotic solvents, such as DMF, DMSO, and acetone, though the (d(xz), d(yz))(4)(d(xy))(1) character is less than that in chloroform and dichloromethane; (iv) the complex adopts the (d(xy))(2)(d(xz), d(yz))(3) ground state in nonpolar solvents, such as toluene, benzene, and tetrachloromethane, because of the lack of hydrogen bonding in these solvents; (v) acetonitrile behaves like nonpolar solvents, such as toluene, benzene, and tetrachloromethane, though it is classified as a dipolar aprotic solvent. Although the NMR results have been interpreted in terms of the solvent effects on the ordering of the d(xy) and d(pi) orbitals, they could also be interpreted in terms of the solvent effects on the population ratios of two isomers with different electron configurations. In fact, we have observed the unprecedented EPR spectra at 4.2 K which contain both the axial- and large g(max)-type signals in some solvents such as benzene, toluene, and acetonitrile. The observation of the two types of signals has been ascribed to the slow interconversion on the EPR time scale at 4.2 K between the ruffled complex with the (d(xz), d(yz))(4)(d(xy))(1) ground state and, possibly, the planar (or nearly planar) complex with the (d(xy))(2)(d(xz), d(yz))(3) ground state.

show abstract

“…The synthesis of the [Fe(TPC)(1-MeIm) 2 ]CF 3 SO 3 compound is achieved by displacement of coordinate triflate from Fe(TPC)-CF 3 SO 3 21 according to eqn. (1).…”

Section: Preparation Of Compoundmentioning

confidence: 99%

Electronic structure of low-spin ferric chlorins: characterization of bis(1-methylimidazole)(meso-tetraphenylchlorinato)iron(iii) triflate

Simonneaux

Kobeissi

Toupet

2002

J. Chem. Soc., Dalton Trans.

Self Cite

View full text Add to dashboard Cite

1H NMR and EPR studies of the electronic structure of low-spin iron(III) isocyanide mesotetraphenylchlorin complexes: a (dxz,dyz)4(dxy)1 configuration from 293 to 4 K †

Cited by 18 publications

References 47 publications

Electronic Structure of Iron Chlorins: Characterization of Bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(III)triflate and Bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(II)

Electronic Structure of Iron Chlorins: Characterization of Bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(III)triflate and Bis(l-valine methyl ester)(meso-tetraphenylchlorin)iron(II)

Effects of Solvents on the Electron Configurations of the Low-Spin Dicyano[meso-tetrakis(2,4,6-triethylphenyl)porphyrinato]iron(III) Complex: Importance of the C−H···N Weak Hydrogen Bonding

Electronic structure of low-spin ferric chlorins: characterization of bis(1-methylimidazole)(meso-tetraphenylchlorinato)iron(iii) triflate

Contact Info

Product

Resources

About