An Yttrium Organic cyclo-P₄ Complex and Its Selective Conversions

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Polyphosphorus Chemistry

Background:

• The direct functionalization of elemental phosphorus (P4) remains a significant challenge in inorganic chemistry.
• Rare-earth metal complexes offer unique reactivity for activating small molecules, including elemental phosphorus.
• Understanding the controlled degradation of P4 is crucial for developing novel phosphorus-containing materials and catalysts.

Purpose of the Study:

• To synthesize a novel rare-earth-metal organic cyclo-P4 complex through direct functionalization of P4.
• To investigate the reactivity and transformations of the synthesized cyclo-P4 complex.
• To explore new pathways for the stepwise degradation of P4 using rare-earth metal alkyl complexes.

Main Methods:

• Synthesis of a rare-earth-metal alkyl complex LYR(THF) (1).
• Direct functionalization of P4 with complex 1 to yield the cyclo-P4 complex (LY·DMAP)2[1,2-R2-cyclo-P4] (2).
• Investigated thermal transformation of complex 2 into a cyclo-P3 cluster (3).
• Studied the reaction of complex 2 with potassium-rare-earth metal (KR) to form a cyclo-P3 complex (4).
• Examined the reaction of complex 2 with hexamethylphosphoramide (HMPA) to afford a P7 complex (6).

Main Results:

• Successfully synthesized the rare-earth-metal organic cyclo-P4 complex (2) via direct P4 functionalization.
• Demonstrated three selective conversions of the cyclo-P4 species through alkyl migration reactions.
• Observed transformations yielding a R2P-substituted cyclo-P3 cluster (3), an unsubstituted cyclo-P3 complex (4), and a Zintl-type P7 complex (6).
• Identified unusual alkyl migrations as the key mechanism in these polyphosphorus complex transformations.

Conclusions:

• The study presents the first synthesis of a rare-earth-metal cyclo-P4 complex by direct P4 functionalization.
• The cyclo-P4 complex serves as a versatile precursor for generating diverse polyphosphorus clusters (cyclo-P3 and P7) via alkyl migration.
• These findings provide novel insights into the stepwise degradation of P4 using metal complexes, opening avenues for phosphorus chemistry.