A Titanocene Based Trans–Bidentate Metalloligand and the Effect of M+ Coordination on the Photophysical Properties of Titanocenes

Patrick Lecture Room, Plyler Hall 126

Pyridine bound transition metal compounds are commonly utilized in the fields of catalysis and supramolecular chemistry. For instance, palladium dipyridyl derivatives have been exploited to generate molecular boxes and utilized as catalysts for cross coupling reactions. While there are numerous examples of trans-spanning diphosphine ligands, there are only a few examples of trans-bidentate ligands that employ nitrogens. One class, the rigid molecule 1,2-bis(pyridin-2-ylethynyl)benzene and its corresponding derivatives have been utilized to form trans-spanning compounds containing both copper and palladium species. The utility of trans-bidentate dipyridyl ligands in catalysis and supramolecular chemistry suggests that developing additional architectures for such ligands would be desirable. Rather than an organic hinge that was the focus of previous ligands, a transition metal hinge might provide the appropriate geometry, while also providing opportunities for the synthesis of heterobimetallic complexes. Our group has been particularly interested in metal-to-metal charge transfer in heterobimetallic donor-?-bridge acceptor complexes with ferrocene donors and titanocene acceptors and sought additional means by which to bind a second metal to a titanocene. Herein, we report the first example of a trans-bidentate dipyridyl ligand with a transition metal (titanocene) hinge and we investigate its coordination with Cu(I) and Pd(II). Additionally, we report the effect of M+ coordination on the photophysical properties of titanocenes.