Photochemistry of (η6-arene)Cr(CO)3 (arene = methylbenzoate, naphthalene, or phenanthrene) in n-heptane solution: Population of two excited states following 400 nm excitation as detected by picosecond time-resolved infrared spectroscopy

Ian P. Clark, Michael W. George, Gregory M. Greetham, Emma C. Harvey, Conor Long, Jennifer C. Manton, Mary T. Pryce

Research output: Journal PublicationArticlepeer-review

19 Citations (Scopus)

Abstract

The photochemistry of (η6-methylbenzoate)Cr(CO)3, (η6-naphthalene)Cr(CO)3, and (η6- phenanthrene)Cr(CO)3 in n-heptane solution was investigated by picosecond time-resolved infrared spectroscopy (TRIR). The observation of two transient IR features in the organic carbonyl region at 1681 and 1724 cm -1 following 400 nm excitation of (η6-methylbenzoate) Cr(CO)3 confirms formation of two excited states which are classified as metal-to-arene charge transfer (MACT) and metal-to-CO charge transfer (MCCT), respectively. Time-dependent density functional theory calculations have been used to support these assignments. Population of the MCCT excited state results in a slow (150 ps) expulsion of one CO ligand. Excitation of (η6-naphthalene)Cr(CO)3 or (η6- phenanthrene)Cr(CO)3 at either 400 or 345 nm produced two excited states: the MCCT state results in CO loss, while the MACT excited state results in a change to the coordination mode of the polyaromatic ligands before relaxing to the parent complex. A comparison of the infrared absorptions observed following the population of the MACT excited state with those calculated for nonplanar polyaromatic intermediates provides a model for the reduced hapticity species.

Original languageEnglish
Pages (from-to)2985-2993
Number of pages9
JournalJournal of Physical Chemistry A
Volume115
Issue number14
DOIs
Publication statusPublished - 14 Apr 2011
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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