Preparation And Structure Of Phosphonium Ions With Intramolecular P N Coordination; Novel Diphosphonium Salts And Ionomer Containing Backbone Hypervalent Phosphorus

Starting from R′R2P (R′ = 8-dimethylamino-1-naphthyl) containing a donor dimethylamino group, the new phosphonium salts [R′R2P(CH2Ph)]+Br– [R = Me (9) or Ph (10)] and [R′R2P(p-CH2C6H4CH2)PR2R′]2+[2Br]2– [R = Ph (12)] have been prepared. An interaction between the N and P atoms is evident from the X-ray crystal structure of 10 the N–P distance being less than the sum of the van der Waals radii of the 2 atoms. The geometry of 10 is that of a monocapped tetrahedron whereas the X-ray crystal structure determination shows essentially regular tetrahedral geometry for the analogous compound without the donor amino group, [(1-Np)Ph2P(CH2Ph)]+Br– (11). Treatment of 1,5-bis(dimethylamino)-2,6-dilithionaphthalene with chlorodiphenylphosphane gave 1,5-bis(dimethylamino)-2,6-bis(diphenylphosphanyl)naphthalene (8) which in the presence of methyl iodide afforded the diphosphonium salt [1,5-bis(dimethylamino)-2,6-bis(diphenylmethylphosphonium)naphthalene]2+[2I]2– (13). Similarly, treatment of 8 with 1 equivalent of benzyl bromide gave the monophosphonium salt [1,5-bis(dimethylamino)-2diphenylbenzylphosphonium-6-diphenylphosphanyl-naphthalene]+[Br]– (14) whereas in the presence of 2 equivalents of the same reagent [1,5-bis(dimethylamino)-2,6-bis(diphenylbenzylphosphonium)naphthalene]2+[2 Br]2– (15) was obtained. The ionomer poly([(1,5-bis{dimethylamino}2,6-bis{diphenylphosphonium}naphthalene)-(P,P-p-xylylene)]2+[2 Br]2–) (16), soluble in liquid SO2, was prepared by treatment of 8 with α,α′-dibromo-p-xylene.