Stepwise substitution of terminal and bridging phosphines in [Pd2(µ-PBut2)(µ-PBut2H)(PBut2H)2]BF4 and the reactivity of [Pd2(µ-PBut2)(PPh3)3]BF4

Abstract

The dipalladium(I) cationic complex [Pd₂(µ-PBu^t₂)(µ-PBu^t₂H)(PBu^t₂H)₂]BF₄ 1, with a central [Pd₂(µ-PBu^t₂)]⁺ core binding two different types of PBu^t₂H molecules, was treated with tertiary phosphines (PR₃, R = Me, Et, Ph or C₆H₄OMe-2). The terminally bonded PBu^t₂H molecules were substituted under mild conditions yielding the new derivatives [Pd₂(µ-PBu^t₂)(µ-PBu^t₂H)(PR₃)₂]BF₄, which still bear a bridging secondary phosphine. The latter can be substituted under more forcing conditions which allow the isolation of the persubstituted [Pd₂(µ-PBu^t₂)(PR₃)_n]BF₄. The reactions of one of these derivatives, [Pd₂(µ-PBu^t₂)(PPh₃)₃]BF₄, with CO, MeCN or isoprene giving, respectively, [Pd₂(µ-PBu^t₂)(PPh₃)₃L]BF₄ (L = CO or MeCN) or [Pd₂(µ-PBu^t₂)(µ-η²∶η²-CH₂CHCMeCH₂)(PPh₃)₂]BF₄ are also described.