Syntheses of Phosphinine-Based Tripodal Ligands

Azaphosphinines and their derivatives

Six-membered heterocycles containing one phosphorus and one nitrogen atom, known as azaphosphinines, have existed in the shadows of their single heteroatom-containing analogues for almost 150 years. Despite this, recent chemistry has seen a rapid increase in publications concerning this uncommon scaffold. Azaphosphinines exist in one of six isomers-there are three possible orientations of the pnictogen atoms and in each of these, the phosphorus is in one of two valences (PIIIvs. PV). This review aims to outline and inform on the synthesis and applications of all six isomers. PV-oxo azaphosphinines are of particular interest to this review as many of the discussed heterocycles either form as the pentavalent species directly or oxidize to this over time. In very recent years the published applications of azaphosphinines have blossomed into subjects spanning several fields of chemistry such as asymmetric catalysis, supramolecular association, cellular imaging, and medicinal chemistry.

Two isomers of a bis(diphenylphosphino)phosphinine, and the synthesis and reactivity of Ru arene/Cp* phosphinophosphinine complexes

Two isomers of a bis(diphenylphosphino)phosphinine have been synthesised, and the Ru coordination chemistry of a 2-phosphinophosphinine extended to include reactions of H₂O across a PC double bond.

Intramolecular apical metal-H-Csp3 interaction in molybdenum and silver complexes

The reaction of HTIMP3 (HTIMP3=tris[1-diphenylphosphino)-3-methyl-1H-indol-2-yl]methane) with AgBF4 and Mo(CO)3(NCCH3)3 leads to Ag(HTIMP3)BF4 and Mo(CO)3(HTIMP3), respectively. The metal centre is coordinated to the three phosphorus atoms of the HTIMP3 ligand, which adopts a facial coordination mode, placing a H-Csp3 hydrogen atom at the apical position close to the metal centre. The solid-state structure of Mo(CO)3(HTIMP3) has been determined by X-ray crystallography, and the data have been used as input parameters for obtaining the optimised geometry of the complex using the B3PW91 functional. The silver structure has been modelled from the X-ray parameters of the molybdenum structure. In addition, theoretical calculations on the H-Csp3 downfield shift upon metal coordination has also been performed. They reproduce the experimental H-Csp3 chemical shifts well and supports that proton deshielding is mainly due to the presence of the metal, since the hydrogen is already located in the cone created by the aromatic-phosphino arms in the free ligand.