Subporphyrinoid Systems: A Theoretical Study of the Effects of the Diheteroatom Substitution in Pyrrole Subunits and of the Nature of the Bridging Meso Linkages

• Published in: Journal of organic chemistry Vol. 75; no. 17; pp. 5904 - 5910
• Main Authors: Sordo, Tomás L, Menéndez, M. Isabel
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 03.09.2010
• Subjects: Chemistry; Computer Simulation; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Magnetic Resonance Spectroscopy; Molecular Structure; Organic chemistry; Preparations and properties; Pyrroles - chemistry; Spectrophotometry, Ultraviolet; Nitrogen heterocycle; Carbon Isotopes; Theoretical study; Distortion; NMR spectrometry; Diketone; Pyrrole derivatives; Planar molecule; Geometrical structure; Absorption spectrometry; Chemical shift; Electronic structure; Density functional method; Spectrophotometry; Carbon 13; Porphyrin derivatives
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo101116h

A theoretical study of the geometry, the electronic structure, the electronic absorption spectra, and 1H and 13C NMR spectra of the [14]subporphine(1.1.1)-hydroxyboron(III) complex, free-base subporphyrin, and its dioxygen and dithio pyrrole substituted derivatives using CH, N, and P as bridging meso linkages was performed at the B3LYP/6-311+G(2d,p)//B3LYP/6-31G(d) theory level. The geometrical structure of these systems is mainly determined by the internal area delimited by the meso atoms and the α-carbon atoms of the pyrrolic rings, and by the number and nature of the atoms located on this area. All the hydroxyboron subporphyrins and dioxo and dithio subporphyrins with CH meso connectors display a conical shaped geometry. The presence of strong repulsions between the atoms on the central zone of the remaining systems provokes a correlative tilting of one of the three rings with loss of the conical shape with important consequences on spectroscopic properties. A particularly interesting case is the dioxosubporphyrin with P connectors in which the large area of the central zone determined by these connectors allows for an almost planar geometry that endows it with special features. The molecules presenting a tilted ring display weak absorption bands. Generally, the intensity of the bands moderately increases when the geometry is cone shaped. The dioxo heterosubporphyrins with CH (conical shape) and P (almost planar) connectors present strong absorption bands. 1H and 13C chemical shifts clearly reflect the effect of geometry distortion provoked by the repulsion among the atoms of the central area of the system indicating a deep perturbation of the π system of the molecules.