Abstract
The symmetrically substituted derivative of a four-member ring 1,3-diaza-2,4-diphosphetidine, 1,3-bis(4-phenylthiazol-2-yl)-2,4-bis(N,N-diethylamino)-1,3-diaza-2,4-diphosphetidine 1 has been obtained by reaction of 2-amino-4-phenylthiazole (II) with tetraethyldiamido-tert-butylphosphite (I). The solid-state structure of compound 1 was determined by single crystal X-ray diffraction.
Compound 1 contains the relatively unusual planar NPNP-ring with trans-arrangement of substituents on the phosphorus atoms. As follows from stereochemical analysis of data obtained from the Cambridge Crystallographic Data Centre (CCDC), this arrangement of the diazadiphosphetidine occurs quite rarely.
DFT results revealed, that nitrogen nonbonding electron pairs undergo an enhanced delocalization into proximal bonds upon planar arrangement of the NPNP ring, however, a simultaneous increase of the ring antiaromaticity is also observed.