1,2σλ-Oxaphosphetanes and Their -Chalcogenides-A Combined Experimental and Theoretical Study.

Although 1,2σλ-oxaphosphetanes have been known for a long time, the "low-coordinate" 1,2σλ-oxaphosphetanes have only been known since their first synthesis in 2018 via decomplexation. Apart from ligation of this P-heterocycle to gold(I)chloride and the oxidation using -chloranil, nothing on their chemistry has been reported so far. Herein, we describe the synthesis of new 1,2σλ-oxaphosphetane complexes (-) and free derivatives (-), as well as reactions of with chalcogens and/or chalcogen transfer reagents, which yielded the -chalcogenides (-; Ch = O, S, Se).

Synthesis of free and ligated 1,2-thiaphosphetanes - expanding the pool of strained P-ligands.

While P(v) 1,2-oxaphosphetanes were investigated in great detail over the past decades, the knowledge about P(v) 1,2-thiaphosphetanes is rather scarce, and P(iii) derivatives are unknown. Herein, we present the synthesis of the first P(iii) complex derivatives formed in the coordination sphere of group 6 metals and, additionally, the first unligated P(iii) 1,2-thiaphosphetanes. The latter display an unusually low HOMO-LUMO gap thus constituting excellent candidates for redox-cycling organocatalysts.