Preparation structure of dithioxo- and diselenoxophosphoranes stabilized by intramolecular coordination with a dialkylamino group

Some ditfaioxophosphoranes 3 stabilized by intramolecular coordination with a dialkylarnino group were prepared, and their structures were analyzed by X-ray crystallography involving [2,4-di-(erf-butyl-6-{isopropYlmethylamino)phenyl](3c), !2,4-di-erf-butyl-6-[(diTnethylamino)methyl]phenyl}- (3f), and (2,4-di-(ert-butyl-6-[2-(dimethylamino)-l,l-dimethylethyl]phenyl} dithioxophosphorane (3h). The bond between the phosphorus atom and the aromatic ring is flexible and the angle narrows with decreasing ring size of the intramolecular coordination. The ³¹P-NMR signals are shifted to higher field with increasing ring size of the intramolecular coordination or strength of coordination. Similarly, the corresponding diselenoxophosphoranes 4 were prepared. Both their ³¹P- and ⁷⁷Se-NMR signals are shifted to higher field with increasing contribution of intramolecular coordination.