Reactions of (sigma-alkynyl)platinum complexes with [Pd(eta3-C3H5)Cl]2. Synthesis of bis(eta2-alkyne)(eta3-allyl)palladium(II) complexes. Crystal and molecular structure of [cis-(PPh3)2Pt(mu-eta1:eta2-CºCtBu)2Pd(eta3-C3H5)](ClO4)

Resumen

The σ-bis and tetraalkynyl anions [cis-Pt(C6F5)2(C≡CR)2] 2- and [Pt(C≡CR)4]2- (R = Ph, tBu, SiMe3) have been shown to be useful reagents for the formation of bis(μ-alkynyl) complexes via halide displacement reactions. They thus react with {[Pd(η3-C3H5)Cl]2} in a 2:1 molar ratio to form anionic heterobinuclear zwitterionic Q[cis-(C6F5)2Pt(μ-η 1:η2-C≡CR)2Pd-(η 3-C3H5)] (Q = PMePh3, R = Ph; Q = NBu4, R = tBu, SiMe3 1a-c) and (NBu4)[(RC≡C)2Pt-(μ-η1:η 2-C≡CR)2Pd(η3-C3H 5)] (R = Ph, tBu, SiMe3 2a-c) complexes. The corresponding trinuclear 1:2 neutral adducts {[Pt(C≡CR)4][Pd(η3-C3H 5)]2) (R = Ph, tBu, SiMe3 3a-c) were formed by the addition of 1 equiv of the tetraalkynyl anions to {[Pd(η3-C3H5)Cl]2}. Binuclear derivative analogue [(PPh3)2Pt(μ-η1:η 2-C≡CR)Pd(η3-C3H 5)](ClO4) (R = Ph, tBu 4a,b) were produced by the reaction of {[Pd(η3-C3H5)Cl]2} with neutral [cis-Pt(PPh3)2(C≡CR)2] (1:2 ratio) in the presence of NaClO4 (excess). The heterobimetallic anionic 1c (R = SiMe3) and cationic 4b (R = tBu) complexes were characterized by X-ray diffraction. In both, the two bridging alkynyl ligands remained σ bonded to the platinum center and η2 coordinated to the palladium one.