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

Abstract

Abstract [L C R P((PhP) 2 C 2 H 4 )][OTf] ( 4 a,b [OTf]) and [L C iPr P(PPh 2 ) 2 ][OTf] ( 5 b [OTf]) were prepared from the reaction of imidazoliumyl‐substituted dipyrazolylphosphane triflate salts [L C 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)C 2 H 4 P(H)Ph) and Ph 2 PH. A stepwise double P−N/P−P bond metathesis to catena‐tetraphosphane‐2,3‐diium triflate salt [(Ph 2 P) 2 (L C Me P) 2 ][OTf] 2 ( 7 a [OTf] 2 ) is observed when reacting 3 a [OTf] with diphosphane P 2 Ph 4 . The coordination ability of 5 b [OTf] was probed with selected coinage metal salts [Cu(CH 3 CN) 4 ]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph 2 PPL C iPr )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(CH 3 CN) 3 ][OTf] 2 (M=Cu, Ag) ( 10 [OTf] 2 , 11 [OTf] 2 ).