Structural and Electronic Properties of Iron(0) PNP Pincer Complexes

Mathias Glatz; Nikolaus Gorgas; Berthold Stöger; Ernst Pittenauer; Liliana Ferreira; Luis F Veiros; Maria José Calhorda; Karl Kirchner

doi:10.1002/zaac.202100015

Structural and Electronic Properties of Iron(0) PNP Pincer Complexes

Z Anorg Allg Chem. 2021 Jul 27;647(14):1429-1435. doi: 10.1002/zaac.202100015. Epub 2021 May 4.

Authors

Mathias Glatz¹, Nikolaus Gorgas¹, Berthold Stöger², Ernst Pittenauer³, Liliana Ferreira^{4

5}, Luis F Veiros⁶, Maria José Calhorda⁵, Karl Kirchner¹

Affiliations

¹ Institute of Applied Synthetic Chemistry Vienna University of Technology Getreidemarkt 9/163-AC 1060 Vienna Austria.
² X-ray Center Vienna University of Technology Getreidemarkt 9/163-OC 1060 Vienna Austria.
³ Institute of Chemical Technologies and Analytics Vienna University of Technology Getreidemarkt 9 A-1060 Vienna Austria.
⁴ Department of Physics University of Coimbra 3004-516 Coimbra Portugal.
⁵ BioISI-Biosystems and Integrative Sciences Institute Faculdade de Ciências Universidade de Lisboa 1749-016 Lisboa Portugal.
⁶ Centro de Química Estrutural and Departamento de Engenharia Química Instituto Superior Técnico Universidade de Lisboa Av Rovisco Pais 1049-001 Lisboa Portugal.

Abstract

In the present work we have prepared and fully characterized several Fe(0) complexes of the type [Fe(PNP)(CO)₂] treating Fe(II) complexes [Fe(PNP)(Cl)₂] with KC₈ in the presence of carbon monoxide. While complexes [Fe(PNP^NMe-iPr)(CO)₂], [Fe(PNP^NEt-iPr)(CO)₂] adopt a trigonal bipyramidal geometry, the bulkier and more electron rich [Fe(PNP^NH-tBu)(CO)₂] is closer to a square pyramidal geometry. Mössbauer spectra showed isomer shifts very close to 0 and similar to those reported for Fe(I) systems. Quadrupole splitting values range between 2.2 and 2.7 mm s^-1 both in experiments and DFT calculations, while those of Fe(I) complexes are much smaller (∼0.6 mm s^-1).

Keywords: Carbon Monoxide; DFT calculations; Iron Complexes; PNP Pincer Ligands.