New Synthetic Procedures to Cafena-Phosphorus Cations: Preparation and Dissociation of the First cyc/o-Phosphino-halophosphonium Salts

摘要

Chlorination of 1,2,3,4-tetracyclohexyl-cyclo-tetraphosphine (2) by PhlCI_2 or PCI_5 in the presence of Me_3SiOTf or GaCI_3 provides a stepwise approach to salts of the first cyc/ophosphino-chlorophosphonium cations [Cy_4P_4CI]~+ ([19]~+) and [Cy_4P_4Cl_2]~(~(2+))([20]~(~(2+))). The analogous iodo derivative [Cy_4P_4l]~+ ([17]~+) is obtained as the tetraiodogallate salt from reaction of 2 with l_2 in the presence of Gal_3. Reactions of the dication [20]~(~(2+)) with PMe_3 or dmpe effect a dissociation of the cyclic framework resulting in the formation of salts containing [Me_3PPCyPCyPMe_3]~(~(2+)) ([27]~(~(2+))), [dmpeCyP]~(~(2+)) ([29]~(~(2+))), and [dmpeCyPCyP]~(~(2+)) ([30]~(~(2+))), respectively. The new cations represent phosphine complexes of the [PCy]~(~(2+)) and [P_2Cy_2]~(~(2+)) cationic fragments from [20]~(~(2+)), demonstrating the coordinate nature of the phosphinophosphonium bonds in cyclo-phosphino-halophosphonium cations. The compounds have been characterized by NMR spectroscopy, single crystal X-ray crystallography, and Raman spectroscopy.