Synthesis Of 1-phenylselenylphosphinidene Complex And Their Insertion Reactions Into Se-Se And S-S Bonds

The ring-opening reaction of bridged ring compounds is the main way to generate electrophilic phosphinidene complexes,but the reaction lacks atomic economy.The retro-[1+2]cycloaddition of phosphirane is a highly atom economical pathway to form transient phosphinidene complexes.However,fragmentation of phosphiranes is profoundly dependent upon the substitution pattern.Therefore,we plan to elucidate the effect of ortho substituents on the ring-opening reaction of phosphirane.Density functional theory(DFT)calculations with 1-phenylselenyl-phosphirane complex provide an insight into phosphirane fragmentation to phosphinidene complexes.FMO and ELF analyses show that the cleavage of two P-Cσ bonds of phosphirane proceeds via an asynchronous concerted pathway.Experiments show that transient[PhSeP-W(CO)s]was generated by dissociation of 1-phenylselenylphosphirane complex at 90℃ and trapped with different reagents.The 1-phenoxylphosphirane complex undergoes[1+2]retroaddition at a comparatively higher temperature which implies that the lone pair of the adjacent atom center of phosphorus plays a major role in phosphirane fragmentation.On the basis of the successful synthesis of[PhSeP-W(CO)5],we study the insertion reaction of phenylselenyl,phenoxy,phenyl and benzyl substituted phosphinidene complexes into non-polar covalent bonds(Se-Se and S-S).The insertion products were successfully obtained at 130℃ after 3 h.It shows that decreasing the Lewis acidity of phosphinidenes by increasing the electron donating ability of adjacency substituent can reduce the yield of the insertion reactions.But the change of electron density of S-S and Se-Se bonds has no significant effect on the reactions.After the formation of Lewis acid-base adducts with phosphinidenes,the migration of cyclic diselenides and disulphide is affected by the rings,resulting in lower yield than chain compounds.The formation of these phosphite ester analogues were characterized by NMR analysis and X-ray crystal structure.The ring-opening reaction of bridged ring compounds is the main way to generate electrophilic phosphinidene complexes,but the reaction lacks atomic economy.The retro-[l+2] cycloaddition of phosphirane is a highly atom economical pathway to form transient phosphinidene complexes.However,fragmentation of phosphiranes is profoundly dependent upon the substitution pattern.Therefore,we plan to elucidate the effect of ortho substituents on the ring-opening reaction of phosphirane.Density functional theory(DFT)calculations with l-phenylselenyl-phosphirane complex provide an insight into phosphirane fragmentation to phosphinidene complexes.FMO and ELF analyses show that the cleavage of two P-C a bonds of phosphirane proceeds via an asynchronous concerted pathway.Experiments show that transient [PhSeP-W(CO)s] was generated by dissociation of1-phenylselenylphosphirane complex at 90 °C and trapped with different reagents.The 1-phenoxylphosphirane complex undergoes [ 1 +2] retroaddition at a comparatively higher temperature which implies that the lone pair of the adjacent atom center of phosphorus plays a major role in phosphirane fragmentation.On the basis of the successful synthesis of [PhSeP-W(CO)5],we study the insertion reaction of phenylselenyl,phenoxy,phenyl and benzyl substituted phosphinidene complexes into non-polar covalent bonds(Se-Se and S-S).The insertion products were successfully obtained at 130 °C after 3 h.It shows that decreasing the Lewis acidity of phosphinidenes by increasing the electron donating ability of adjacency substituent can reduce the yield of the insertion reactions.But the change of electron density of S-S and Se-Se bonds has no significant effect on the reactions.After the formation of Lewis acid-base adducts with phosphinidenes,the migration of cyclic diselenides and disulphide is affected by the rings,resulting in lower yield than chain compounds.The formation of these phosphite ester analogues were characterized by NMR analysis and X-ray crystal structure.