A Photomodulable organometallic catalyst

A Photomodulable organometallic catalyst

Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari di Venezia, Calle Larga S. Marta 2137, 30123, Venezia. giulio.bianchini@unive.it

In homogeneous catalysis proper functionalization of a metal center with an appropriate ligand system often represents the most rewarding strategy to achieve the best performance, in terms of activity, selectivity and sometimes recycle. Alternatively the performance of a homogeneous catalyst can be modulated by means of interaction with external stimuli, mimicking what occurs in Nature where the activity of enzymes is triggered on and off as a function of the request of the organism. A possible approach exploits supramolecular interactions (host-guest) between the catalytic species and another chemical entity which interact as a second sphere ligand.[1_{] In this}

case the restoration of the original activity requires the addition of a third chemical species. A more simple system can be obtained if considering the light as affector in catalysis.[2_{] The preparation of}

an organometallic complex bearing a molecular tag that undergoes a photochemical reaction could deliver a new generation of homogeneous catalysts whose activity, selectivity and recycle properties can be tailored by employing an appropriate light source.[3_]

In the present contribution are presented the synthesis, the light induced behavior and preliminary results in homogeneous catalysis of a series of new generation soft Lewis acid Pt(II) complexes bearing a coumarinic moiety in the phosphane ligand. Such species undergo reversible 2+2 photo-cycloaddition if irradiated at the proper wavelength changing both their steric and geometrical properties. One of these systems demonstrated a high catalytic activity difference between its light un-reacted and reacted forms in the alkene isomerization reaction.

1 _{[] A. Cavarzan, A. Scarso, P. Sgarbossa, G. Strukul, J. N. H. Reek J. Am. Chem. Soc.2011, 133,}

2848-2851;

2 [] S. Hetch, R. S. Stoll Angew. Chem. Int. Ed. 2010, 49, 5054-5075;