Syntheses and Coordination Studies of 2‐(Phosphanylmethyl)pyridine Dioxide toward Silver (I)

From polygons to polyhedra through intermediate structures. A shape measures study of six-atom inorganic rings and clusters

Among the wealth of well-established molecular structures, inorganic rings and clusters present an overwhelming variety of geometries that chemists try to describe with a limited assortment of regular polygons and polyhedra. In the case of six-atom structures we usually employ the hexagon, the pentagonal pyramid, the trigonal prism and the octahedron. More often than not, however, real world structures deviate from those ideal geometries, and we try to cope with non-ideality by adding adjectives such as distorted, twisted, puckered or flattened, additionally nuanced by adverbs such as slightly, significantly or severely. This contribution presents a systematic structural perspective of six-atom groups in molecules by means of a continuous shape measures (CShM) analysis. The shape of a group of N points is defined by all the sets of 3 N Cartesian coordinates that can be generated by rigid translation, rotation, or isotropic scale change. Among all possible arrangements of N points in space, we select as reference shapes the corresponding regular N-vertex polygons and polyhedra, together with univocally defined combinations thereof (e.g., two coplanar or perpendicular edge-sharing squares). The present CShM study allows us to classify most of the structures not only by their closeness to a particular regular shape, but also by quantifying their position along minimal distortion interconversion pathways between two regular shapes.

A Multifunctional Pincer Ligand for Cobalt-Promoted Oxidation by N2 O

The divalent cobalt complex of the diprotic pincer ligand bis-pyrazolylpyridine, (H₂ L)CoCl₂ , is dehydrohalogenated twice by LiN(SiMe₃ )₂ in the presence of PEt₃ to give monomeric S=1/2 LCo(PEt₃ )₂ (1), fully characterized in the solid-state and solution as a square pyramidal monomer with a long axial Co-P bond. This 17-electron species reacts in time of mixing with N₂ O to form L₂ Co₂ (μ-OPEt₃ ) (2)+3 OPEt₃ , the former the first example of phosphine oxide bridging two transition metals. The same products are formed from O₂ , and divalent cobalt persists even in the presence of excess oxidant. Species (2) catalyzes oxygen atom transfer (OAT) for generation of O=PEt₃ from PEt₃ from either N₂ O or O₂ . Bridging and terminal cobalt oxo intermediates are suggested, and the electron donor power, and potential redox activity of the dianionic pincer ligand is emphasized.

Adjustable coordination of a hybrid phosphine–phosphine oxide ligand in luminescent Cu, Ag and Au complexes

The mixed-donor ligand shows variable binding ability with respect to d¹⁰ metal ions to afford a series of mono- and dinuclear complexes with tunable photophysical characteristics.