An Antiaromatic Porphyrin Complex:  Tetraphenylporphyrinato(silicon)(L)2 (L = THF or Pyridine)

• Published in: Journal of the American Chemical Society Vol. 127; no. 35; pp. 12212 - 12213
• Main Authors: Cissell, Julie A, Vaid, Thomas P, Rheingold, Arnold L
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 07.09.2005
• Subjects: Atomic and molecular physics; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Density-functional theory; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Physics; Frontier orbital; Molecular structure; Nitrogen heterocycle; Organic ligand; Theoretical study; Silicon Complexes; Electronic structure; Molecular orbital method; Pyridine; Complexes Mixed; Heterocyclic oxygen compounds; Density functional method; Tetrahydrofuran; Metalloporphyrin; Antiaromaticity
• DOI: 10.1021/ja0544713
• ISSN: 0002-7863

Treatment of Si(TPP)Cl2 (TPP = tetraphenylporphyrinato) with 2 equiv of Na/Hg in THF yields the reduced porphyrin complex, Si(TPP)(THF)2, in which the porphyrin ring system has an oxidation state of 4− and the complex is antiaromatic. Single-crystal X-ray diffraction reveals that Si(TPP)(THF)2 is highly ruffled and exhibits a unique C−C bond length alternation around its periphery. In addition, experimental 1H and 29Si NMR chemical shifts and NICS (nucleus-independent chemical shift) calculations on a model compound indicate a strong paratropic ring current in Si(TPP).