Persistence of a Ru3(μ-CO)3(CO)5 Cluster Bound to a PNNP “Expanded Pincer” Ligand in Different Protonation States

We report the synthesis and characterization of Ru3(μ-CO)3(CO)5-type cluster complexes bound to a dinucleating PNNP ‘expanded pincer’ ligand. Each bidentate PN pocket of the ligand chelates a single ruthenium center of the cluster and can undergo deprotonation concomitant with dearomatization of its naphthyridine core. Although the cluster bearing a partially dearomatized ligand reacts with H2, we found no indication that this proceeds via a pathway involving metal-ligand cooperativity