P-P Condensation and P-N/P-P Bond Metathesis: Facile Synthesis of Cationic Tri- and Tetraphosphanes.

[L P((PhP) C H )][OTf] (4 a,b[OTf]) and [L P(PPh ) ][OTf] (5 b[OTf]) were prepared from the reaction of imidazoliumyl-substituted dipyrazolylphosphane triflate salts [L P(pyr) ][OTf] (3 a,b[OTf]; a: R=Me, b=iPr; L =1,3-dialkyl-4,5-dimethylimidazol-2-yl; pyr=3,5-dimethylpyrazol-1-yl) with the secondary phosphanes PhP(H)C H P(H)Ph) and Ph PH. A stepwise double P-N/P-P bond metathesis to catena-tetraphosphane-2,3-diium triflate salt [(Ph P) (L P) ][OTf] (7 a[OTf] ) is observed when reacting 3 a[OTf] with diphosphane P Ph . The coordination ability of 5 b[OTf] was probed with selected coinage metal salts [Cu(CH CN) ]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph PPL )Au} ][OTf] (9[OTf] ) was unexpectedly formed as a result of a chloride-induced P-P bond cleavage. The weakly coordinating triflate anion enables the formation of the expected copper(I) and silver(I) complexes [(5 b)M(CH CN) ][OTf] (M=Cu, Ag) (10[OTf] , 11[OTf] ).