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 di methylamino 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)] h ave 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 s hows essentially regular tetrahedral geometry for the analogous compound wi thout the donor amino group, [(1-Np)Ph2P(CH2Ph)]Br-+(-) (11). Treatment of 1,5-bis(dimethylamino) -2,6-dilithionaphthalene with chlorodiphenylphosphan e gave 1,5-bis(dimethylamino)-2,6-bis(diphenylphosphanyl)-naphthalene (8) w hich 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)-2-diphenylbenzylphosphoni um-6-diphenylphosphanyl-naphthalene](+) [Br](-) (14) whereas in the presenc e of 2 equivalents of the same reagent [1,5-bis(dimethylamino)-2,6-bis(diph enylbenzylphosphonium)naphthalene] (2+)[2 Br](2-) (15) was obtained. The io nomer poly([(1,5-bis{dimethylamino}- 2,6-bis{diphenylphosphonium}naphthalen e)-(P,P-p-xylylene)](2+)[2 Br](2-)) (16), soluble in liquid SO2, was prepar ed by treatment of 8 with alpha,alpha'-dibromo-p-xylene.