1,2σ 3 λ 3 -Oxaphosphetanes and Their P -Chalcogenides-A Combined Experimental and Theoretical Study.

Although 1,2σ 5 λ 5 -oxaphosphetanes have been known for a long time, the "low-coordinate" 1,2σ 3 λ 3 -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 ortho -chloranil, nothing on their chemistry has been reported so far. Herein, we describe the synthesis of new 1,2σ 3 λ 3 -oxaphosphetane complexes ( 3a - e ) and free derivatives ( 4a - e ), as well as reactions of 4a with chalcogens and/or chalcogen transfer reagents, which yielded the P -chalcogenides ( 14 - 16a ; Ch = O, S, Se). We also report on the theoretical results of the reaction pathways of C -phenyl-substituted 1,2 σ 3 λ 3 -oxaphosphetanes and ring strain energies of 1,2σ 4 λ 5 -oxaphosphetane P -chalcogenides.