Supramolecular bulky phosphines comprising 1,3,5- triaza-7-phosphaadamantane and Zn(salphen)s: structural features and application in hydrosilylation catalysis
Résumé
The use of the commercially available, bifunctional phosphine 1,3,5-triaza-7-phosphaadamantane (abbreviated as PN 3) in conjunction with a series of Zn(salphen) complexes leads to sterically encumbered phosphine ligands as a result of (reversible) coordinative Zn–N interactions. The solid state and solution phase behaviour of these supramolecular ligand systems have been investigated in detail and revealed their stoichiometries in the solid state observed by X-ray crystallography, and those determined in solution by NMR and UV-Vis spectroscopy. Also, upon application of these supramolecular bulky phosphines in hydrosilylation catalysis employing 1-hexene as a substrate, the catalysis data infer the presence of an active Rh species with two coordinated, bulky PN 3 /Zn(salphen) assembly units having a maximum of three Zn(salphen)s associated per PN 3 scaffold, with an excess of bulky phosphines hardly affecting the overall activity.