SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF A TETRAARYLDIPHOSPHORUS CATION AND A DIALKYLPHOSPHONIUM SALT

The compound 5-chorodibenzophosphole reacts with an equivalent amount or an excess of Al2Cl6 in methylene chloride solution to afford the re spective tetraorganodiphosphorus cations [R(2)P(Cl)PR(2)][AlCl4] (R(2) = o,o'-dibenzophenylato), 1. However, reaction of t-Bu(2)PCl with an equivalent amount or an excess of Al2Cl6 in CH2Cl2 gives rise to a pho sphonium ion, [t-Bu(2)PCl(2)][AlCl4] (2) as the major product, while r eaction with 0.5 equivalent Al2Cl6 leads to a mixture of cationic orga nophosphorus species. In addition, the compound 5-chloro-bis-carborany lphosphole (3) was synthesized. Compound 3 fails to react with Al2Cl6 or GaCl3, yet does afford 5-fluoro-bis-carboranylphosphole (4) upon tr eatment with AgSbF6. The molecular structures of 1 and 2 have been det ermined from X-ray structural analysis. The former consists of a plana r P(III) heterocyclic moiety joined to an essentially tetrahedral P(TV ) heterocycle by a single P-P bond. The charge is balanced by the hept achlorodialuminate ion. Compound 1 crystallized in the triclinic space group <P(1)over bar> with a = 10.5798(8) Angstrom, b = 11.3656(9) Ang strom, = 13.8190(11) Angstrom, alpha = 107.985(3)degrees, beta = 100.9 135(2)degrees, gamma = 103.636(2)degrees, V = 1478 Angstrom(3), Z = 2, R = 0.047. Compound 2 crystallized in the monoclinic space group, P2( 1) with a = 7.2471(8) Angstrom, b = 12.0235(12) Angstrom, c = 9.9651(1 1) Angstrom, beta = 90.473(3)degrees, V = 868 Angstrom(3) Z = 2, R = 0 .109.