Generation of a π-Bonded Isomer of [P4]4− by Aluminyl Reduction of White Phosphorus and its Ammonolysis to PH3

By employing the highly reducing aluminyl complex [K{(NON)Al}]<sub>2</sub> (NON=4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene), we demonstrate the controlled formation of P<sub>4</sub> <sup>2-</sup> and P<sub>4</sub> <sup>4-</sup> complexes from white phosphorus, and chemically reversible inter-conversion between them. The tetra-anion features a unique planar π-bonded structure, with the incorporation of the K<sup>+</sup> cations implicit in the use of the anionic nucleophile offering additional stabilization of the unsaturated isomer of the P<sub>4</sub> <sup>4-</sup> fragment. This complex is extremely reactive, acting as a source of P<sup>3-</sup> : exposure to ammonia leads to the release of phosphine (PH<sub>3</sub> ) under mild conditions (room temperature and pressure), which contrast with those necessitated for the direct combination of P<sub>4</sub> and NH<sub>3</sub> (>5 kbar and >250 °C)

Structural snapshots in reversible phosphinidene transfer: synthetic, structural, and reaction chemistry of a Sn═P double bond

The reaction of amido-substituted stannylenes with phospha-Wittig reagents (Me3PPR) results in release of hexamethyldisilazane and tethering of the resulting −CH2PMe2PR fragment to the tin center to give P-donor stabilized stannylenes featuring four-membered Sn,C,P,P heterocycles. Through systematic increases in steric loading, the structures of these systems in the solid state can be tuned, leading to successive P–P bond lengthening and Sn–P contraction and, in the most encumbered case, to complete P-to-Sn transfer of the phosphinidene fragment. The resulting stannaphosphene features a polar Sn═P double bond as determined by structural and computational studies. The reversibility of phosphinidene transfer can be established by solution phase measurements and reactivity studies

Probing the extremes of covalency in M-Al bonds: lithium and zinc aluminyl compounds

Synthetic routes to lithium, magnesium, and zinc aluminyl complexes are reported, allowing for the first structural characterization of an unsupported lithium-aluminium bond. Crystallographic and quantum-chemical studies are consistent with the presence of a highly polar Li-Al interaction, characterized by a low bond order and relatively little charge transfer from Al to Li. Comparison with magnesium and zinc aluminyl systems reveals changes to both the M-Al bond and the (NON)Al fragment (where NON=4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene), consistent with a more covalent character, with the latter complex being shown to react with CO<sub>2</sub> via a pathway that implies that the zinc centre acts as the nucleophilic partner