Fine-Tuning of Electronic Structure of Cobalt(II) Ion in Nonplanar Porphyrins and Tracking of a Cross-Hybrid Stage: Implications for the Distortion of Natural Tetrapyrrole Macrocycles

Qiuhua Liu; Xi Zhang; Wennan Zeng; Jianxiu Wang; Zaichun Zhou

doi:10.1021/acs.jpcb.5b08431

Fine-Tuning of Electronic Structure of Cobalt(II) Ion in Nonplanar Porphyrins and Tracking of a Cross-Hybrid Stage: Implications for the Distortion of Natural Tetrapyrrole Macrocycles

J Phys Chem B. 2015 Nov 5;119(44):14102-10. doi: 10.1021/acs.jpcb.5b08431. Epub 2015 Oct 22.

Authors

Qiuhua Liu^{1

2}, Xi Zhang², Wennan Zeng², Jianxiu Wang¹, Zaichun Zhou²

Affiliations

¹ College of Chemistry and Chemical Engineering, Central South University , Changsha 410083, China.
² Key Laboratory of Theoretical Organic Chemistry and Functional Molecule of the Ministry of Education; School of Chemistry and Chemical Engineering, Hunan University of Science and Technology , Xiangtan 411201, China.

PMID: 26461496
DOI: 10.1021/acs.jpcb.5b08431

Abstract

The core size of the porphyrin macrocycles was closely related to their stability of the different electron structure in the central metal ion. Cobalt(II) ions can undergo a conversion in electron configurations upon N4 core contraction of 0.05 Å in nonplanar porphyrins, and these ions still maintain low spin forms after and before conversion. The structural fine-tuning can induce the appearance of a cross-hybrid stage [d(x(2)-y(2))sp(2) ↔ d(z(2))sp(2)] based on quadrilateral coordination of the planar core. The results indicate that the configuration conversion plays a key role in electron transfer in redox catalysis involving cobalt complexes. The electronic properties of six monostrapped cobalt(II) porphyrins were investigated by spectral, paramagnetic, and electrochemical methods. The macrocyclic deformations and size parameters of Co-containing model compounds were directly obtained from their crystal structures.