The complexed 1,3-diphospha-2-arsaallyl radical and its cationic and anionic derivatives.

Area of Science:

• Organometallic Chemistry
• Radical Chemistry
• Main Group Chemistry

Background:

• The synthesis and characterization of novel organometallic radical species are crucial for advancing chemical understanding.
• Diphospha-arsaallyl systems are relatively unexplored, presenting an opportunity for new discoveries in inorganic and organometallic chemistry.

Purpose of the Study:

• To synthesize and characterize a novel 1,3-diphospha-2-arsaallyl radical complex.
• To investigate the electronic structure, stability, and redox properties of this new radical system.
• To explore the reactivity of the radical, including its protonation, reduction, and oxidation.

Main Methods:

• Photolysis of [Cp*As{W(CO)(5)}(2)] in the presence of Mes*P=PMes* to generate the target radical.
• Spectroscopic characterization including EPR, NMR, and IR spectroscopy.
• X-ray diffraction analysis for structural elucidation of key compounds.
• Electrochemical methods (reduction and oxidation) to study redox behavior.

Main Results:

• Successful synthesis of the 1,3-diphospha-2-arsaallyl radical [(CO)(5)W(mu,eta(2):eta(1)-P(2)AsMes*(2))W(CO)(4)] (2a).
• EPR spectroscopy confirmed the unpaired electron is localized on the terminal phosphorus atoms.
• Isolation and characterization of protonated, reduced, and oxidized derivatives (6a, 7a, 8a), representing the first complexed redox congeners of this system.
• Identification of decomposition products, including Z- and E-isomers of Mes*P=PMes*{W(CO)(5)} (3, 4) and [As(2){W(CO)(5)}(3)] (5).
• Analogous oxidation of a triphosphaallyl radical led to a cation that underwent CH activation.

Conclusions:

• The synthesized 1,3-diphospha-2-arsaallyl radical exhibits a stable pi-allylic system with significant electron density on the phosphorus atoms.
• The study successfully generated and characterized unprecedented complexed redox congeners of the diphospha-arsa-allyl system.
• The reactivity studies revealed insights into the stability and decomposition pathways of these novel organometallic radicals.