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

[LC (R) P((PhP)(2)C2H4)][OTf] (4 a,b[OTf]) and [(LCP)-P-iPr(PPh2)(2)][OTf] (5 b[OTf]) were prepared from the reaction of imidazoliumyl-substituted dipyrazolylphosphane triflate salts [LC (R) P(pyr)(2)][OTf] (3 a,b[OTf]; a: R=Me, b=iPr; L-C (R)=1,3-dialkyl-4,5-dimethylimidazol-2-yl; pyr=3,5-dimethylpyrazol-1-yl) with the secondary phosphanes PhP(H)C2H4P(H)Ph) and Ph2PH. A stepwise double P-N/P-P bond metathesis to catena-tetraphosphane-2,3-diium triflate salt [(Ph2P)(2)((LCP)-P-Me)(2)][OTf](2) (7 a[OTf](2)) is observed when reacting 3 a[OTf] with diphosphane P2Ph4. The coordination ability of 5 b[OTf] was probed with selected coinage metal salts [Cu(CH3CN)(4)]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph2PPLCiPr)Au}(4)][OTf](4) (9[OTf](4)) 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(CH3CN)(3)][OTf](2) (M=Cu, Ag) (10[OTf](2), 11[OTf](2)).