A Porphyrin as a Binucleating Ligand: Preparation and Crystal Structure of a Porphyrin Complex Containing a Coordinated B2O2 Ring

Belcher, Warwick J.; Breede, Matthis; Brothers, Penelope J.; Rickard, Clifton E. F.

doi:10.1002/(sici)1521-3773(19980504)37:8<1112::aid-anie1112>3.0.co;2-q

Cited by 43 publications

(8 citation statements)

References 6 publications

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“…The porphyrin macrocycle provides a very versatile scaffold, exploited by Nature and chemists alike, chiefly due to its capacity to coordinate many elements in its central cavity. Brothers et al have developed the somewhat unusual class of porphyrin and related macrocycle derivatives featuring two inner coordinated boron atoms [46][47][48][49][50][51][52][53][54][55][56] in a 1,3-difluoro-1λ 4 ,3λ 4 -diboroxan-1,1,3,3-tetrayl group, abbreviated (BF)O(BF), that in porphyrins has each boron bonded in a transoid fashion to two adjacent pyrrolic nitrogen atoms. This, in principle, facilitates an encapsulated B−O−B linkage that could lead to isolable akamptisomers.…”

Section: Resultsmentioning

confidence: 99%

A new fundamental type of conformational isomerism

et al. 2018

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Isomerism is a fundamental chemical concept, reflecting the fact that the arrangement of atoms in a molecular entity has a profound influence on its chemical and physical properties. Here we describe a previously unclassified fundamental form of conformational isomerism through four resolved stereoisomers of a transoid (BF)O(BF)-quinoxalinoporphyrin. These comprise two pairs of enantiomers that manifest structural relationships not describable within existing IUPAC nomenclature and terminology. They undergo thermal diastereomeric interconversion over a barrier of 104 ± 2 kJ mol, which we term 'akamptisomerization'. Feasible interconversion processes between conceivable synthesis products and reaction intermediates were mapped out by density functional theory calculations, identifying bond-angle inversion (BAI) at a singly bonded atom as the reaction mechanism. We also introduce the necessary BAI stereodescriptors parvo and amplo. Based on an extended polytope formalism of molecular structure and stereoisomerization, BAI-driven akamptisomerization is shown to be the final fundamental type of conformational isomerization.

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Section: Resultsmentioning

confidence: 99%

A new fundamental type of conformational isomerism

et al. 2018

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“…The in-plane vibrational frequencies were determined computationally for Ni(II)porphine complexes with induced TE by increasing the distance between the nonbonding NN atoms along one axis (∥NN) in 0.1 Å intervals over a 0–1.2 Å range. To date, the porphyrin complex exhibiting the largest TE that has been fully characterized experimentally is B 2 O 2 (BCl 2 )(TpClPP) complex with ΔNN of 1.14 Å . In porphyrins with such a large TE, the NN distance perpendicular to the elongated axis is shortened to within 2.43–2.73 Å range.…”

Section: Resultsmentioning

confidence: 99%

“…To date, the porphyrin complex exhibiting the largest TE that has been fully characterized experimentally is B 2 O 2 (BCl 2 )-(TpClPP) complex with ΔNN of 1.14 Å. 69 In porphyrins with such a large TE, the NN distance perpendicular to the elongated axis is shortened to within 2.43−2.73 Å range. To fully explore the experimentally observed spread of TE distortions, the NN distance perpendicular to the longer axis (⊥NN) was also reduced in 0.1 (Å) intervals over a 0−0.4 (Å) range.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Diboron Porphyrins: The Raman Signature of the In-Plane Tetragonal Elongation of the Macrocycle

Novikova

Gordon

et al. 2018

J. Phys. Chem. A

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We describe an unusual in-plane type of porphyrin core distortion, tetragonal elongation (TE), observed experimentally in diboron porphyrins. The vibrational spectra of several of these complexes exhibit shifts that we have assigned to this TE distortion by comparing experimental spectra with DFT computational findings. The influence of TE in porphyrin systems was isolated using DFT analysis of the well-known model compounds Ni(II)porphine and Zn(II)porphine, with the macrocycle ring constrained to eliminate the influence of out-of-plane (OOP) distortions. A significant down-shift in frequencies was observed for porphyrin normal vibrational modes, particularly the in-plane A/B modes that are dominated by contributions from stretching and bending of C-C coordinates. In contrast, TE had little effect on the v(Pyr) and δ(Pyr) modes, though the lowered symmetry of the system resulted in significant splitting of the B and B modes. The impact of the TE distortion upon the diboron porphyrin vibrational spectrum was probed experimentally using Raman spectroscopy of BO(BCl)(TTP), BOF(TTP), and BOPhOH(TTP) (TTP = 5,10,15,20-(tetra- p-tolyl)porphyrin). Comparing the experimentally obtained spectral signatures to the computational findings allowed us to assign the large shifts observed for the v and v modes to the TE distortion in diboron porphyrins.

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“…Porphyrins are versatile biological macrocycles − and have a diverse coordinating ability. Thus, porphyrins have four coordinating nitrogens and a suitable cavity to complex with metals, metalloids, and nonmetals. − However, if the metal/nonmetal/metalloid is smaller in size, more than one metal/nonmetal/metalloid can complex with the porphyrin. − For example, two smaller B(III) ions complex with porphyrin 1 since the porphyrin cavity is large enough to accommodate two B(III) ions, as shown in Chart . However, when one pyrrole ring is removed from the porphyrin, the resulting macrocycles are called triphyrin(2.1.1)s.…”

Section: Introductionmentioning

confidence: 99%

“…6−9 However, if the metal/ nonmetal/metalloid is smaller in size, more than one metal/ nonmetal/metalloid can complex with the porphyrin. 10−15 For example, two smaller B(III) ions complex with porphyrin 16 1 since the porphyrin cavity is large enough to accommodate two B(III) ions, as shown in Chart 1. However, when one pyrrole ring is removed from the porphyrin, the resulting macrocycles are called triphyrin(2.1.1)s. In triphyrin(2.1.1)s, the three pyrrole rings are connected in a conjugated cyclic fashion via four methine carbons.…”

Section: ■ Introductionmentioning

confidence: 99%

Synthesis, Structure, Spectral, and Anion Sensing Studies of an Aromatic meso-Fused Boron(III) Benzitriphyrin(2.1.1) Complex

2021

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An aromatic tricoordinated organo B(III) complex of benzitriphyrin(2.1.1) was synthesized by treating the nonaromatic phlorin analogue of meso-fused benzitriphyrin(2.1.1) with BCl3 in triethylamine/toluene and refluxing for 2 h. The X-ray structure revealed that B(III) was in a trigonal-planar geometry and was coordinated to two nitrogen atoms and one carbon. Insertion of the small B(III) ion into the meso-fused phlorin analogue resulted in transforming the nonaromatic phlorin analogue to an aromatic B(III) benzitriphyrin(2.1.1) complex. Spectral and electrochemical studies supported the aromatic nature of the B(III) complex of benzitriphyrin(2.1.1). Theoretical studies supported the major contribution of the 18π delocalization pathway toward the aromatic nature of the B(III) meso-fused benzitriphyrin(2.1.1) in comparison to the 22π delocalization pathway. The B(III) benzitriphyrin(2.1.1) complex acts as a specific colorimetric and fluorogenic F–/CN– ion sensor.

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A Porphyrin as a Binucleating Ligand: Preparation and Crystal Structure of a Porphyrin Complex Containing a Coordinated B2O2 Ring

Cited by 43 publications

References 6 publications

A new fundamental type of conformational isomerism

A new fundamental type of conformational isomerism

Diboron Porphyrins: The Raman Signature of the In-Plane Tetragonal Elongation of the Macrocycle

Synthesis, Structure, Spectral, and Anion Sensing Studies of an Aromatic meso-Fused Boron(III) Benzitriphyrin(2.1.1) Complex

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