Redox Activity, Ligand Protonation, and Variable Coordination Modes of Diimino-Pyrrole Complexes of Palladium
Journal
Inorganic Chemistry
Journal Volume
57
Journal Issue
12
Pages
7044-7050
Date Issued
2018
Author(s)
McNeece, Andrew J.
Chang, Mu-Chieh
Filatov, Alexander S.
Anderson, John S.
Abstract
Ligand-based functionality is a prominent method of increasing the reactivity or stability of metal centers in coordination chemistry. Some of the most successful catalysts use ligand-based redox activity, pendant protons, or hemilability in order to specifically accelerate catalysis. Here we report the diimino-pyrrole ligand Tol,CyDIPyH (Tol,CyDIPy = 2,5-bis( N-cyclohexyl-1-( p-tolyl)methanimine)pyrrolide), which exhibits all three of these ligand properties. Metalation of Tol,CyDIPy to Pd gives the pseudo-square planar complex (Tol,CyDIPy)PdCl, which upon reduction forms a mixture of products, including a Pd(I)-Pd(I) dimer wherein Tol,CyDIPy bridges the dimeric unit. Upon addition of PMe3, the imine arms of (Tol,CyDIPy)PdCl are displaced to yield (Tol,CyDIPy)Pd(PMe3)2Cl, where the Tol,CyDIPy ligand binds in a monodentate fashion. This complex can be reduced to generate a ligand-based radical, as shown by EPR spectroscopy. Finally, (Tol,CyDIPy)PdCl also can be protonated at the imine arm, exhibiting a total of three different coordination modes across this series of complexes. Taken together, these studies show that Tol,CyDIPy exhibits notable flexibility in its coordination and redox chemistry.
SDGs
Type
journal article