Constraining s 3 -P compounds in nontrigonal, entatic geometries has proven to be an effective strategy for promoting biphilic oxidative addition reactions more typical of transition metals.A lthough qualitative descriptions of the impact of structure and symmetry on s 3 -P complexes have been proposed, electronic structure variations responsible for biphilic reactivity have yet to be elucidated experimentally. Reported here are PK-edge XANES data and complementary TDDFT calculations for aseries of structurally modified P(N) 3 complexes that both validate and quantify electronic structure variations proposed to give rise to biphilic reactions at phosphorus.T hese data are presented alongside experimentally referenced electronic structure calculations that reveal nontrigonal structures predicted to further enhance biphilic reactivity in s 3 -P ligands and catalysts.

Metal–ligand cooperativity (MLC) relies on chemically reactive ligands to assist metals with small-molecule binding and activation, and it has facilitated unprecedented examples of catalysis with metal complexes. Despite growing interest in combining ligand-centered chemical and redox reactions for chemical transformations, there are few studies demonstrating how chemically engaging redox active ligands in MLC affects their electrochemical properties when bound to metals. Here we report stepwise changes in the redox activity of model Ru complexes as zero, one, and two BH3 molecules undergo MLC binding with a triaryl noninnocent N2S2 ligand derived from o-phenylenediamine (L1). A similar series of Ru complexes with a diaryl N2S2 ligand with ethylene substituted in place of phenylene (L2) is also described to evaluate the influence of the o-phenylenediamine subunit on redox activity and MLC. Cyclic voltammetry (CV) studies and density functional theory (DFT) calculations show that MLC attenuates ligand-centered redox activity in both series of complexes, but electron transfer is still achieved when only one of the two redox-active sites on the ligands is chemically engaged. The results demonstrate how incorporating more than one multifunctional reactive site could be an effective strategy for maintaining redox noninnocence in ligands that are also chemically reactive and competent for MLC.

Constraining s 3 -P compounds in nontrigonal, entatic geometries has proven to be an effective strategy for promoting biphilic oxidative addition reactions more typical of transition metals.A lthough qualitative descriptions of the impact of structure and symmetry on s 3 -P complexes have been proposed, electronic structure variations responsible for biphilic reactivity have yet to be elucidated experimentally. Reported here are PK-edge XANES data and complementary TDDFT calculations for aseries of structurally modified P(N) 3 complexes that both validate and quantify electronic structure variations proposed to give rise to biphilic reactions at phosphorus.T hese data are presented alongside experimentally referenced electronic structure calculations that reveal nontrigonal structures predicted to further enhance biphilic reactivity in s 3 -P ligands and catalysts.